Why Join the Naturalists?

We can’t survive without access to the fresh air, water, food, shelter, spiritual enrichment, aesthetics, personal restoration, and nature’s other essentials that allow us to celebrate life on this third planet from the sun. Our very physical and mental health depend on nature. But our popular cultures have detached us from Earth’s natural systems and cycles, the very forces and processes that rule our world, resulting in perilous dysfunctions that even AI cannot treat or resolve. And have you checked the news lately? Our nature deficit disorders are having tragic consequences that threaten humans, millions of other species, and the very future of our planet.

The UC California Naturalist statewide natural resource education and service program is coming to the rescue! This extraordinary program fosters “a diverse community of naturalists and promotes stewardship of California’s natural resources through education and service.” They draw you in with refreshing truth telling: “We cannot protect and restore California’s unique ecology without an environmentally literate, engaged public.” … and … “Becoming a naturalist offers a chance to explore nature and deepen your understanding of how nature works.” And then they make you offers you can’t refuse: “Are you interested in nature? Do you love CA’s diverse ecosystems? Embark on an immersive adventure with experts. Deepen your understanding of ecology and forge lasting friendships. This course has graduated career starters through retirees, all learning together to become a community of Certified California Naturalists.” How could we resist this magical week in Yosemite?

Follow Us on this Magical Natural History Tour

Join me on this journey as I share some of our day-to-day discoveries from the experts in the field who live this stuff. Images and excerpts from more than 32 pages of field notes prove that, even after leading hundreds of field classes and field trips with thousands of my students and colleagues over more than three decades, we and I will never stop learning. (The stories here are taken from my personal field notes and some occasional background research. All photos are mine and are not edited or manipulated in any way.) Let your curiosity fly like the clouds and wings over Half Dome in this Yosemite natural history expedition.   

Chris Cameron was our organizer, leader, and master instructor for these exceptional learning experiences. Without Chris, a one-of-a-kind tour guide and educator, we wouldn’t be able to retrace our steps because there wouldn’t be any. He demonstrated phenomenal skills in gathering seasoned professionals and curious students together to learn within nature’s living laboratories. And his people skills are the icing on the cake!    

Each day of our expedition gets its own page in this story; simply click to the page that matches the day and/or subject. You are encouraged to follow me chronologically to soak in the full benefits. Here’s how it’s all organized:

Day/Page One (Saturday, 4-12-2025): From the Central Valley up to ECCO in Oakhurst
Day/Page Two (Sunday, 4-13-2025): Geology, Creation, and More than 100 Million Years
Day/Page Three (Monday, 4-14-2025): Healthy Forests and Roaring Falls
Day/page Four (Tuesday, 4-15-2025): Cliffs, Bats, Fires, Technology and Botany
Day/Page Five (Wednesday, 4-16-2025): Following the Trail to Native Americans and American Settlers
Day/Page Six (Thursday 4-17-2025): Grazing, Logging, and Hunting, Oh My!
Day/Page Seven (Friday 4-18-2025): Sharing Our Discoveries

Day One (Saturday, 4-12-2025): From the Central Valley up to ECCO in Oakhurst:

A drive north along Hwy 41 from Fresno eventually takes you out of the Central Valley, which shines as the country’s most productive agricultural landscapes. This sprawling valley is vital in making California the number one agricultural state in the nation, as the state generates well more than $50 billion income per year from farm products.     

As the road gradually slopes up toward Sierra Nevada foothills, we find ourselves surrounded by open grasslands that recall the vast prairies that once dominated the Golden State’s inland valleys before the Spanish arrived. You will notice cattle grazing on pastoral rolling hills, landscapes occasionally interrupted and sliced by serpentine streams and rivers meandering from east to west, out of higher elevations and into the valley. (These lush narrow riparian strips are what remains (less than 10%) of the broad gallery forests that once extended on both sides of streams and rivers flowing out of the Sierra Nevada.) Today’s hills turn verdant green by April and erupt into rainbow displays of wildflowers such as lupine. But the grasses and flowers will soon dehydrate to the golden browns of punishing summer drought, leaving their seeds in parched soils, waiting for next winter’s rains and next spring’s renewed fantastical displays.

But another invader has recently rivaled the seasonal nonnative grasses on these gentle slopes at the base of the Sierra Nevada Mountains: humans and their developments. Developers are gobbling up some of these landscapes and attracting people who want to escape urban crowds, chaos, and traffic. “Build it and they will come” continues to spread across these landscapes that tourists have been passing by for decades on their way to the high country. Entire wannabe self-sufficient communities have been sprouting and extending over the grasslands and oak woodlands. And the changes are not coming without controversy. As these ecosystems are scraped up and paved, some locals are watching their reasons for living here disappear, while recent arrivals find relative peace and quiet in their perceived bucolic settings. Talk of limited water and other resources, habitat destruction, loss of open spaces, pollution, land values, affordable housing, and increasing traffic congestion is replacing the traditional agrarian discourse and cultures. Such noticeable changes are stretching and then redefining our perceptions of wildland-urban interfaces. The end of this world as we knew it may be just one more development away.

Once we get up above about 1,000’ elevation, where a little more precipitation falls and temperatures are a bit cooler, an assortment of scattered oak trees pops up above the ground cover. At about 2,000’, the woodlands thicken and diversify to include gray pine and other drought-tolerant trees. These scraggly pines with long, grayish needles and big cones often appear bent and twisted as though they were dancing through the night and were suddenly frozen in a pose by the morning light, waiting for summer’s fire or winter’s first merciful rehydrating showers. As we progress higher, slopes tend to steepen and we notice mixed pine forests as we look up toward snow in the distant high country. (We will revisit Sierra Nevada’s vegetation zones in more detail during the next few days.) We drop down into the town of Oakhurst (elevation 2,274’), nestled in its little valley that many consider the gateway to Yosemite. Traveling up and a little farther north, we finally turn off Hwy 41 and will settle, hang our hats, and share tasty meals at ECCO each night, which is a pretty typical option for tour and educational groups looking for base camps in and near Yosemite: “The Episcopal Conference Center Oakhurst (ECCO) has been serving the religious, educational and non-profit conference and retreat needs of Fresno, Madera, Mariposa and the rest of California’s Central Valley since 1982.”       

This is where we can hear Yosemite calling from just several miles away. The rolling landscapes in and around ECCO (about 3,100’ ASL) is populated with mostly open oak and pine woodland. The deciduous oak trees are just beginning to sprout by mid-April, careful to avoid any late-season freezes. A giant pond with a fountain demands attention, decorating the property and attracting more than our senses. Depending on the season, an assortment of waterfowl and other wildlife visit or live around the water (more than 100 species of birds have been recorded there), demonstrating animal behaviors that deserve a line or two in our field notebooks.

Wild turkeys are particularly entertaining as they dive out of their trees (where they roost at night to avoid predators) early in the morning and trot around during the day. Their toe-walking and dragging one foot in front of the other leaves an arrowhead-like trail. Turkeys are not native to California, but numerous attempts to introduce them finally became successful so that their numbers multiplied since the 1960s until they now total about 250,000 in the state. These omnivores mate and lay their eggs during spring. Gestation takes about a month and they are most vulnerable to predators (such as coyote, bobcats, foxes, some birds, and domesticated animals) after hatching. Adults may become nuisances around humans as they show aggression with their flapping and pecking; their droppings also get pretty messy. They’ve been known to damage gardens and attack their reflections in windows and on the sides of cars.  

The turkeys remind us that every species of plant and animal, every landscape, rock, cloud, water drop, and weather event have captivating natural history stories to tell. Informative and useful narratives grow from research that connects all of us to our natural world. We can see why this is just one of the naturalist programs across the US. Master instructor Chris Cameron started our course by summarizing how we celebrate biodiversity with environmental literacy, scientific and social understanding, by honing our interpretive skills, and practicing collaborative conservation. We reviewed our state’s bioregions and geomorphic provinces (from page 29 in our required California Naturalist Handbook), which coincide with the physiographic regions we have explored in numerous stories on this website and in my publications. And we recognized how the California Floristic Province, a biological hotspot with its thousands of species that include a large percentage of endemics, is experiencing a biodiversity crises as increasing numbers of those unique plants and animals are threatened with extinction. We recognize how naturalists’ work has become crucial as we observe, communicate, and act to build essential links between scientists and the average person. After dinner, our first day and evening ended with my presentation that summarized some fascinating properties of water and the weather patterns and climates that rule over our plant communities, topics we have highlighted on this website and in my recent California Sky Watcher book and statewide tour.      

Click (below) to the next page and day.

The post Cal Naturalists Invade Yosemite first appeared on Rediscovering the Golden State.

Whether they are considered nature’s great cathedrals or breathtaking scenery without rivals, there is nothing quite like them on this planet. They helped inspire me and millions of others to learn more about the natural forces and processes that are shaping our world and how we all fit in. They and other grand landscapes in California and beyond motivated me to become the student, researcher, teacher, and naturalist that I am today. We have featured Yosemite Valley and Kings Canyon landscapes in previous stories that you will find in this project and website. In this story, we explore Zion Canyon.

How has it changed and how does this high desert canyon compare to and contrast with our Yosemite? Join me, your master ranger and natural history interpreter armed with 50 years of observations and field experiences, as I guide you to discover the science behind the scenery.

On the surface, there are some uncanny similarities between our Sierra Nevada’s Yosemite and Utah’s Zion. Each of these valleys sits at about 4,000 feet (1,200 m) above sea level, surrounded by thousands of feet of vertical rock walls soaring abruptly above their eroding rivers. Each of their names begin with the last letters of our alphabet, monikers that recall the people and cultures who once settled in these other-worldly canyons. But great differences stand out when we look a little closer.     

We returned to Zion’s campgrounds during the prolonged and historic heat wave of July 2023, a month when the high temperature at their weather station (near their Human History Museum and Visitor Center) made it to 110° F (43° C) on two days. Only four days of that month had high temperatures just below 100° F (38° C), which is closer to the July average. (The highest temperature ever recorded at Zion was 115°, including July 10 and 11, 2021.) This contrasts with their typically lowest temperatures in the teens over the winter and a low of 14° F (-10° C) on January 31, 2023.

Imagine experiencing such a 124° temperature range in one location within less than six months! Welcome to cold winters and hot summers common to the thin dry continental air of the high desert. During this trip, nature forced us to alter our daily schedule so that we could hike the dry trails during early mornings and evenings and spend the hottest afternoons within the shaded narrows, immersed in the Virgin River, or at the museum or visitor center. We were rewarded with comfortable evenings to view bats darting around and then thousands of stars rotating in the dark night sky.

Weather patterns and climates in Zion are glaringly different from our Yosemite, which drains and opens toward the west, facing the Pacific Ocean. As wet winter storms stream off the Pacific, they dump copious amounts of orographic rain and snow as they glide up Sierra Nevada’s western slopes. (Check out our earlier story on the atmospheric rivers of 2023 and an even earlier story following a water drop.) Yosemite Valley averages more than 36 inches (>91 cm) of precipitation per year and the surrounding high country receives even more.

But by the time those Pacific storms skim over southern Utah’s high desert, they are usually spent, leaving only trace amounts of precipitation. Zion Canyon averages only 15.7 inches (40 cm) of precipitation and 3.8 inches (10 cm) of snow each year, compared to the massive snow drifts that accumulate in the Sierra Nevada each season. Also in contrast to our Yosemite and Kings, Zion has a distinct late summer rainy season associated with the Southwest (North American) monsoon, averaging more than an inch of rain each month from July through October. And though Yosemite may briefly be dampened by infrequent isolated summer storms, such quick hitters are not reliable precipitation producers or drought busters in what John Muir coined our Range of Light.

Torrential summer rains soaked Zion and the Desert Southwest in 2022, causing extensive flash flooding. But the North American monsoon did not perform during our visit on this sizzling July of 2023. Only 0.05 inches was recorded on the only day of precipitation that month (July 25). The fickle monsoon thunderstorm cloudbursts and flash floods will repeatedly wash out roads and trails and carry people away in the debris during one summer and then be disappointing no shows the next. Plants and animals and people who have not adapted to these high desert weather extreme realities do not survive. There is even a late summer rainy season flowering cycle on exhibit in the Southwest and across the Colorado Plateau. This is also why, when cumulus clouds begin boiling into thunderheads within the thermals that rise in summer’s midday heat, we are warned to steer clear of Zion’s narrows and slot canyons that can become violent cascading death traps within minutes. You can thank these powerful gully washers for helping to carve the deep canyons such as Zion that have made Colorado Plateau scenery world famous. In contrast, Yosemite’s Merced River and other Sierra Nevada streams and their ability to erode and deposit are dependent on runoff and snowmelt from those winter storms off the Pacific.

The Sierra Nevada and Colorado Plateau are composed of very different rock formations lifted by very different tectonic forces. The core of Yosemite and the Sierra Nevada is mostly made of massive granitic batholiths that cooled and crystalized from gargantuan underground magma chambers formed in subduction zones around 100 million years ago. More recent vertical faulting has elevated their solid granitic escarpments along steep eastern slopes until high Sierra Nevada peaks reach more than 14,000 feet (4,267 m) above sea level, while western slopes more gradually descend toward the Great Central Valley.

In contrast, the Colorado Plateau is underlain by thousands of feet of mostly sedimentary deposits that also date back more than 100 million years. Millions more years later, heat, pressure, and nature’s glues had lithified the particles into sedimentary rocks. The relatively undisturbed layers were more recently and gradually warped upward by compressional forces until the highest points of the plateau soar over 12,000 feet (>3,658 m) ASL. Gravity’s pull on water flowing from such lofty elevations has energized streams to cut deep canyons into Sierra Nevada’s granitic plutons and into the Colorado Plateau’s vulnerable layers of sedimentary rock formations.

The Grand Canyon is often used as the classic example of how a powerful river (the Colorado) can erode deep chasms as surrounding landscapes are lifted higher. Weathering and erosion will eventually widen the incised narrows over time. The relatively young Zion Canyon is also widening as the Virgin River cuts through it.  

Yosemite and other Sierra Nevada canyons have been carved by floods from wet winter storms and snowmelt that runs off impressive snow packs well into the summer. But the most spectacular high country Sierra Nevada valleys and canyons were also extensively carved by alpine (mountain/valley) glaciers during previous glacial periods. As the flowing ice scraped out deep high-elevation cirques and U-shaped trenches through preexisting mountain canyons, glacial moraine rock piles were deposited downstream, leaving dramatic Ice Age landscapes. (Check out our webpage story from 2019, Norway vs. California, where we examine such glacial grandeur.)

Today’s summer storms contribute relatively little runoff into today’s Sierra Nevada streams that follow those canyons. On the Colorado Plateau, gentler cold winter rains and melting winter snows also add to frigid runoff into the canyons. And like Sierra Nevada rock formations, cycles of freezing and thawing during winter help to crack and physically weather rocks so that blocks are liberated to break off from the cliffs and eventually be carried away after they disintegrate into smaller pieces. But summer’s violent flash floods are responsible for transporting much of that loose rock and sediment downstream in Zion. And only the highest peaks and ridges of the Colorado Plateau exhibit some glacial topography; Zion Canyon and Desert Southwest landscapes were not carved by powerful Ice Age glaciers such as those that once scraped through Sierra Nevada high country.  

There are also glaring differences between Yosemite and Zion in the color and texture of their rock walls. The granitic rocks of the Sierra Nevada are dominated by lighter minerals of quartz and feldspar, but are often speckled with darker crystals containing more iron and other heavier elements. This massive stew of magma chamber chemicals solidified into a solid salt-and-pepper matrix of rocks and minerals.

As the mountains were lifted, overlying rocks were weathered and stripped away, exposing them to weathering and erosion. Chemical weathering processes can be seen as dark stains and vertical streaks on the cliffs where iron and other darker elements oxidize in the water and air. Physical weathering processes include exfoliation, the pressure release that breaks massive rocks into thin skins or onion-like layers to slide and fall downslope. (Check out our website story where we follow a grain of sand.)

In contrast, the sedimentary layers of Zion are clearly and classically stacked with the older deposits on the bottom and the younger rock formations on top of them. (Still younger rocks that once capped them have been eroded and washed away long ago.) Click here for more rock layer details. The Virgin River has sliced through all of them like a sharp knife through a layer cake: nature’s road cuts. Relatively resistant lighter-colored sandstones are dominated by sandy grains with more quartz and feldspar. The layers grading from sandstones to siltstones and mudstones and shales that contain more iron and other heavier elements tend to oxidize into rusty and red colors when exposed to air and water; thinner skins of these weathered surfaces are sometimes referred to as desert varnish. And so, the highly-resistant lighter-colored speckled cliffs and canyons of the Sierra Nevada look quite different from the thousands of feet of vermilion layers of sedimentary rocks weathering in Zion. In both cases, millions of years of internal mountain building forces and external denudational processes have conspired to sculpt some of the most spectacular landscapes on Earth.

Contrasts between our Sierra Nevada and the Colorado Plateau (and particularly Yosemite and Zion) are also noticeable within their plant and animal communities. In both regions, you can find the classic vegetation zones grading from Lower Sonoran grasslands and prairies to Upper Sonoran chaparral and open woodlands, to Transition Zone woodlands and open forests, to Canadian Zone cooler and wetter forests, to still loftier subalpine Hudsonian plant communities, into the highest Arctic-Alpine Zone islands. But wetter Sierra Nevada slopes nurture lusher forests with species such as Giant Sequoias (Sequoiadendron gianteum, the largest trees on Earth) that you won’t find on the drier Colorado Plateau.

So, as you climb up from lower elevations in Zion toward higher elevations on the Colorado Plateau, you will notice high desert xeric species. They include Rabbitbrush (Ericameria nauseosa), Big Basin Sagebrush (Artemesia tridentata), and several different species of buckwheat. A little higher up, you will find what some call pygmy woodlands. Pinyon pines (Pinus monophylla and Pinus edulis) grow with live oaks and other oak species that shed their leaves, growing from shrubs into small trees. They mix with Utah Juniper (Juniperus osteosperma) at lower elevations around 4,000-5,500 feet in the Upper Sonoran and Red Cedar (Juniperus scopulorum) at higher elevations above 5,000 feet in Transition and Canadian Zones. Ponderosa Pines (Pinus ponderosa) appear and grow denser at higher elevations as we make our way into wetter mixed conifer and aspen forests with Douglas Fir (Pseudotauga menziesii), White Fir (Abies concolor), White Pine (Pinus strobiformus), and Quaking Aspen (Populus tremuloides). You also will find a host of colorful wildflowers decorating the understories at these higher elevations. Several species bloom throughout the summer, nurtured by those monsoon thundershowers that more commonly soak the cooler high plateau.

As with riparian communities in the Sierra Nevada, biomass and species diversity dramatically increase along and adjacent to stream and river courses. Where soils remain damp and the relative humidity increases around water courses in Zion, look for denser stands of Fremont Cottonwood (Populus fremontii), Red Birch (Betula occidentalis), various willow species, cattails, and rushes. As you enter the narrows where natural springs and seeps erupt from the sandstone cliff faces, look for fern and other water-loving species that combine in rock cracks to form delicate hanging gardens. Water might also be king in California, but life-giving moisture can transform Colorado Plateau’s dehydrated high desert into productive ecosystems that support numerous species of plants and animals.

Zion’s birds share the advantage of flying to water and food sources. We spotted some raptors, roadrunners, ravens, turkey vultures, and a condor flying overhead. But the real flying shows in Zion start just after sunset, when a seemingly chaotic air show of bats dart around, using their sophisticated radar to hunt and keep insect populations under control. You will also find the greatest number of species and densest populations of animals around Zion’s water courses. We saw wild turkeys, mule deer, and fox in the canyon. Raccoons, skunks, bobcats, porcupines, and owls are also found in the riparian habitats near water, mostly at night. Coyote can be heard howling around the canyon as they hunt in the twilight and darkness. Though American Beavers (Castor Canadensis) have burrowed their lodges into the banks of the Virgin River, they are difficult to spot. They don’t build beaver dams seen along other western rivers, since the river-altering structures would be destroyed by frequent flash floods. Look for the chewing scars on cottonwood trees near the river. All of this gnawing and other beaver activity usually peak during overnight hours, when it is more difficult for predators to hunt them.

As with Yosemite, humans have impacted Zion mammals and cut predator populations in the canyon. There are only a few cougars in the entire park. Such extermination and displacement of mountain lions by early farmers and ranchers and then crowds of visitors caused an unnatural explosion of deer populations. These ubiquitous browsers then feed on cottonwood and other seedlings to reduce the normal rate of plant regrowth. The results include decreasing biodiversity and increasing impacts on populations of many different riparian species. Add efforts to control reoccurring flood damage and you can see how natural channel flow has been destabilized along the Virgin River. This is another classic example of how human impacts can become ripple effects that can change natural systems and cycles and then entire landscapes, even in our national parks.

And that brings us full circle to what Yosemite and Zion might have most in common: they are perfect examples of unique landscapes of grandeur and national parks that we are loving to death. Yosemite is just about 200 miles (or four hours) from Bay Area cities, just over two hours from Central Valley population centers, and about 300 miles (6 hours) from LA. Generations of traditional Yosemite National Park lovers live in these California conurbations. Zion is only about 160 miles (2.5 hours) from a growing Las Vegas. Each of these nearby major metropolitan areas welcomes millions of tourists each year and many of these visitors clamor to squeeze a visit to one of these iconic parks into their itineraries. Unlike those of us who adore our national parks as places to find peace and solitude and to experience and learn about nature, the average visitor spends only a few hours on the ground in those national parks. Millions of people each year exploit them as social media selfie checkoff lists.

The crowds began choking Yosemite Valley decades ago, especially on summer weekends. They brought massive traffic jams, pollution, chaos, and amusement park atmospheres in what were supposed to be exceptional natural environments to be cherished and preserved for the benefit of future generations. Yosemite experimented with reservation systems from 2020-21 and a peak hours reservations system in 2022. Park officials are currently using data gathered from these experiments to develop a Visitor Access Management Plan and you are invited to provide your input. Avid naturalists and backcountry hikers have also been impacted, with most backcountry trails and wilderness areas requiring permits. Growing crowds traipsing to the top of Half Dome (a round-trip hike of about 15 miles with a 4,800-foot elevation gain) eventually created dangerous and sometimes deadly conditions on the steep and slippery dome. I’ve trudged to the top a few times over the years, but today’s permit system limits 300 hikers per day to make use of the chains and steps that lead up the side of the dome.  

Zion National Park is challenged with similar dilemmas: how do our most beloved and popular parks offer access to the greatest number of people, without ruining the nature experience for each visitor and compromising the mission and integrity of our national parks?

Several years ago, Zion’s crowds multiplied as nearby Las Vegas grew and the Utah Office of Tourism began promotions to attract visitors from other states and from around the world. It worked too well if you enjoyed Zion for its nature experiences. The summer traffic and crowds in the canyon became so chaotic, the park was forced to close the road into the canyon to vehicles and require visitors to take the free shuttle from early spring into late fall. Another amusement park atmosphere erupted especially on summer weekends as overwhelmed tourists jammed the overwhelmed visitor center. Others were herded through the maze of winding chains that eventually led them into shuttles where they were crammed like sardines, hoping to eventually be dropped off at key stops to search for their elusive solitude. Add some stifling summer heat and you can see why rangers who wanted to interpret and share the beauty and magic of nature have been forced into crowd control that sometimes turns into safety concerns and crime control after visitors reach their boiling points; good for the businesses in adjacent Springdale, not so good for anyone seeking a quiet nature experience.

And as if to mimic Yosemite’s Half Dome, the narrow chain path up to Angel’s Landing finally got so popular, it turned into a dangerous line of frustrated climbers scrambling over one another. And so, similar to Half Dome, the National Park Service has been stringently enforcing their Angels Landing Pilot Permit Program. I’ve also meandered up the steep switchbacks to this popular peak a few times in past decades, but don’t attempt these memorable climbs without your permit these days.

Whether there are too many people searching for their peace and quiet in nature, or too many people searching for their perfect selfies to post on social media, I don’t offer any better solutions to the crowd control problems that have plagued these otherwise magical wonderlands during recent years. I do know that our world has changed since we could roll in and get first-come, first-served camping spots during the summer in our most spectacular national parks. And I wish the folks at the National Park Service the very best as they struggle to balance the often conflicting serve and preserve missions.

For your part, it is best to visit these magnificent gems off season during weekdays when possible. Or, you can find your solitude at nearby less popular and more remote natural sanctuaries; there are still plenty to choose from that can be just as rewarding and many have been highlighted in stories on this website. In California, some of these retreats are closer to home and more easily accessible than you might think.

If you have a little more time, come along on the following bonus trip. Let’s move up to the plateau more than 3,400 feet (>1036 m) above the canyon along what is called the West Rim Trail to see how the biogeography at higher elevations around Zion National Park is so different from the hotter and drier deserts below. We will leave the crowds behind and then leave you on the high plateau above 7,000 feet (>2,130 m) in the Zion wilderness where summers are delightfully cool (if you can avoid the occasional thunderstorms) and winters are icy cold. For those looking for an introduction to Zion from the National Park Service, check out the link at the end of our story.

Before you go, visit the official National Park Service website that will help you prepare for your adventures: https://www.nps.gov/zion/index.htm

The post Zion vs Yosemite: the Science behind the Splendor first appeared on Rediscovering the Golden State.

Forward: Sand Grain Abbreviated Autobiography 

Let me introduce myself. I am a grain of sand. You have seen me resting or moving along the ground, probably around your feet. You may have even trapped me in your shoes or dragged me into your home. Though you may not have paid attention, my sparkling crystals were shouting out to share my enthralling stories of adventure and intrigue that span millions of years of natural history in the Golden State.  

There are much older and younger rocks, pebbles, and sand grains, but my story began about 100 million years ago. It started deep below the surface in a massive melt that you call a magma chamber. This scalding, churning mass formed as a dense, relatively thin ocean plate slid east and was subducted beneath a less-dense, more buoyant continental plate that rode on top of it. I was dragged with other materials of the ocean crust that were later mixed, incorporated into, and melted with the continental crust in very high temperature environments. As the dynamics changed and the subduction zone migrated away, I cooled and crystallized with millions of tons of other materials around me. In my case, I grew into a large, tough quartz crystal, though I was surrounded by some darker crystals with different chemistries. I remained in this still-warm-but-gradually-cooling environment, deep below the surface, resting for millions of years.

Nearly 80 million years later (more than 20 million years ago), tectonic activity lifted me along with the surrounding granitic rock materials. Overlying rock formations were eroded away, exposing us at the surface in a very different California. Weathering broke us into smaller fragments so that erosion, energized by running water, carried us away, toward the ancient coastline that was a little farther east compared to today’s seashore. There, we were deposited, buried below layers of fresh sediment, and glued and pressed into sedimentary rock layers, where we rested for nearly 20 million more years. Just a few million years ago, we were lifted again by tectonic activity.

In what seemed to be a repeat performance, overlying layers of rock were eroded away until we were exposed at the surface again, this time within our beds of sandstone, only to be subject to a fresh round of weathering. I eventually broke out as a chunk of sandstone, was whittled down to a sand grain, and got carried into a stream, until I was deposited on the beach. There, I got caught in the wave zone and pushed down the beach where I was discovered for this story.

Looking to the future, I will eventually be carried back into the surf and deposited into a deep submarine canyon. As tons of new sediments are deposited on top of me, I will be pressed and incorporated into sandstone again. I will wait there for millions more years for the future internal forces or heat sources that might transform me yet again, as I journey through the eternal rock cycle. Remember that there are billions of other California sand grains that may share similar or quite different stories about where they came from and where they are going; they all contribute to the Golden State’s incredibly diverse landscapes and natural history.

Though I’ve just summarized my adventures, there is much more to learn from my experiences. They are as much about me as they are about you, since we are all being impacted by the powerful and dynamic Earth cycles and systems that can destroy or nurture us. So, I challenge you to read on through the following sagas, recounting some details of my escapades from a more scientific point of view. They include long periods of sedentary calm, punctuated by violent upheavals and turbulent migrations, through millions of years of Earth history in California.

Preface: Following a Grain of Sand

This is a story about the physical systems and cycles which have shaped and continue to sculpt the Earth around us and the sand grain that we follow. They include long periods of intense internal heat and pressure, followed by undisturbed tranquility and isolation, succeeded by steady upheavals of unsettling tectonic activity, fueled by Earth’s internal engines and heat sources. These enduring environments are interrupted by relatively brief intervals of alterations and radical transformations that involve exposure to harsh environments and exciting, turbulent, action-packed scenes, driven by Earth’s powerful external forces.

Because they have been located on or near plate boundaries, California’s landscapes have long displayed some of the best examples of how tectonic forces can, relatively rapidly, lift terrains high above their base levels. These steep, freshly exposed slopes quickly become playgrounds for energized external, denudational processes that collaborate to degrade landscapes back down, often to the sea. These highly energized, often counterbalancing forces dominate the destiny of our California sand grain.

Your latest trip to the coast could never rival the more than 100-million-year-long odyssey that finally delivered our sand grain to the same beach that you now share. We dare to recognize here the significance of the time-honored method of time keeping known as the sand clock or hour glass, as it compares to geologic time. Could it be more than a coincidental metaphor? Could the sand grains sifting through our hour glass, counting seconds, minutes, and hours, simply be impersonating the sand grains circulating in Earth’s cycles as they count time by the decades, centuries, and millions of years?

Armed with our knowledge about Earth history, we might rethink our uninformed perceptions of a grain of sand. We cast aside our previous dismissals, such as “dirt cheap” or “all we are is dust in the wind”, elevating sand to the respect it has earned in our world with “old as dirt” and “solid as a rock”. Because, as you will see, our sand grain is far more than solid as a rock, as it represents an artifact of fascinating natural history, evidence of millions of years of Earth systems and cycles that continue to this day and will continue long after we have perished. You don’t have to look far: as we follow our curiosity, more pieces of this sand puzzle fall into place. They fit together to paint this incredibly diverse and colorful picture we call California. Following our grain of sand opens new windows, clears our lenses, and clarifies our place in this world and how we might fit in. Science guides us to learn more from this sand grain’s magical mystery tour that beckons us.    

We have divided our story into five parts and individual pages that follow our sand grain: Part I: From the Cauldron below into the Light Above; Part II: Roundabout Trip to the Beach; Part III: On the Beach and into the Ocean; Part IV: Sand Grain Natural History Glossary of Explanations and Definitions; and Part V: Sand Grain Journeys California Picture Book. Simply click on to that page if you wish to skip to another part.

Part I: From the Cauldron below into the Light Above               

We begin more than 100 million years ago, during the Cretaceous Period of the Mesozoic Era. Though much of California was still below the ocean, mountain building was well underway and steep ancient ranges were emerging above the sea. This helps explain why there are few dinosaur fossils in the Golden State compared to some other western states just toward the east, where there were more expansive terrains above the ocean: limited Mesozoic terrestrial environments in California included few habitats that could support dinosaur populations.

Local Mesozoic mountain building was energized by a colossal subduction zone just to the west. A dense, but thin ocean plate was thrust below a much more buoyant continental plate, dominating the dynamic geology across California for millions of years. This is somewhat similar to the dynamics off the coast of far northern California and the Pacific Northwest today. Tremendous heat was generated as materials from the ocean crust were plastered and ground into the continent. (The internal source of heat that has been fueling plate tectonics and melting rock materials comes from deeper within the Earth, generated by intense pressure and friction and the gradual decay of radioactive elements.)

As the ocean crust was subducted, its mafic chemistry (with darker and heavier material higher in iron and magnesium) melted and became more buoyant. As this hot, thin, runny magma made its way up into the continental crust, more felsic (sialic) materials melted into it. These high-silica rocks added minerals lighter in color and weight, and they made the melt more viscous. As the ratios of silicon and oxygen (compared to heavier, darker elements) increased, the mix of now gooey ingredients slowed its migration toward the surface. (Silicon and oxygen are the two most common elements found on Earth’s surface; rocks with higher amounts of these elements have lower melting temperatures and, therefore, tend to be more viscous when they melt.) Though some of the magma erupted at the surface to form various volcanic rocks, much of the magma chamber remained emplaced, churning below the surface of the continental crust. Stranded thousands of feet (or meters) below the surface, most of the melt gradually cooled and crystallized to form a giant granitic pluton.

Parts of this massive batholith, with a diverse range of chemical properties, cooled and crystalized at different rates in different locations over millions of years. It would eventually be named the Sierra Nevada Batholith and it and rocks with similar stories would, in due course, form the foundations of most of today’s major mountain ranges in the Golden State. The rock and sand grain we follow was “born” in this environment. Since it formed from millions of covalent bonds of silicon and oxygen, it would be called a quartz crystal. Because the bonding is so strong, quartz is a relatively tough crystal to break down and because silicon and oxygen bonds form crystals light in color and weight, these are typical characteristics of quartz. Furthermore, these magma chambers cooled very slowly deep below the surface, allowing the crystals to grow to very large sizes that can be easily recognized by the unaided eye. Combine all these factors and we see why we find so many rocks in the Sierra Nevada and many other California mountain ranges displaying large, light-colored crystals.   

E1: Go to explanation E1 in our glossary to view how silicon dioxide bonds to forms quartz.

You will often also notice a scattering of darker crystals that decorate these rocks. These geofreckles formed as a variety of other elements bonded with the silicon and oxygen atoms to create darker minerals.

E2: Go to explanation E2 to see how various elements combine to form minerals that then mingle to form intrusive igneous rocks.   

E2a: Orthoclase feldspar.

E2b: The structure of mica.

E2c: Identifying mica and its chemical composition.

You can see how those massive granitic batholiths have left us with tons of familiar rocks possessing varying chemistries. They are mostly dominated by the elements silicon and oxygen, which combine with some of the other elements to build minerals such as the quartz, feldspars, and micas so common in these granitic rocks. You might even find some darker amphibole in the granitic batholiths. And as the iron and magnesium content increases further, we grade away from the granites and into the more mafic rocks.

E3: Go to E3 for more information about igneous rocks (including volcanic rocks) that differ from our granitic rocks. 

As tectonic activity lifted the granitic core rocks and mountains were built, overlying rock formations were stripped away until our sand grain in its rock emerged at the surface. About 20 million years ago, it was exposed and weathered, eroded, and transported out of its pluton. But remember that most of the Golden State’s major mountain ranges have foundations dominated by granitic batholiths and they have, for millions of years, been shedding rocks and crystals that tend to be highly felsic (higher in silica and lighter in weight and color). Also recall that quartz’s silicon and oxygen covalent bonds are strong, allowing these crystals to survive much of the weathering and erosional processes that might dissolve and destroy other minerals with weaker bonds. These high quartz content sands may eventually be deposited in layers and lithified to become sandstones. This is exactly what happened to our sand grain.

The post Natural History of a Grain of Sand first appeared on Rediscovering the Golden State.

Please allow me to explain.

For those of you not in the know, the expression “New York Minute,” refers to something done very fast.  We don’t usually think of erosional processes as happening with haste. Rather it is another expression, “geologic time,” which is often used to highlight the oceans of time it takes constructive and destructive processes to shape Earth’s surface.  In this realm of eons and eras, things happen in agonizingly slow fashion.  You can safely look away for a moment, grab a beverage, and not worry about missing any of the action.

That’s right folks, don’t touch that dial …

But when it comes to erosional landforms, badlands are one of the speed demons of geomorphology.  These loosely compacted formations are often composed of soft, unconsolidated deposits, conglomerates, or friable sedimentary rocks.  But would you believe that landscapes such as this can potentially be shaped by the elements so quickly, that you might actually witness the process in real time? As it turns out, that rapidity of change is an important factor in badlands formation. More on that in another minute — see what I did there?

Badlands topography is distinguished by its lack of vegetation. These grounds are riddled with narrow gullies and ravines that more often than not, have steep and plunging gradients. Such slopes make it hard for plants to find a foothold. Speaking of feet, overland travel through such areas is often arduous. Though a short hike, my traipsing around in this area collecting pictures and video for this story proved difficult. It has been postulated that this fact is the primary reason why these features are so named.

Don’t shuffle off to Buffalo, or Manhattan, to find them …

Badlands as a feature of the landscape are quite uncommon in New York or elsewhere east of the Mississippi. I should know. I grew up in Connecticut. There is nothing remotely resembling these landforms anywhere to be found on the East Coast. Humid environments, like those found in the Empire State, lend themselves to vegetation cover. Vegetation helps anchor the soil, regolith, and other loosely consolidated sediments.  There is no doubt that erosion still happens in the “wet” East. It just tends to happen more slowly and usually in less dramatic fashion with less striking results.

When badlands do occur in such areas it is usually prompted by disturbances (fires, floods, avalanches etc.) that temporarily alter the landscape. Left to their own devices, these lands usually revegetate themselves quickly enough so that they don’t grow into the formations we see in Quatal Canyon. Indeed, even in this area, the badland features comprise a relatively small area of only a few hundred acres in extent around the steepest escarpments and terrain.

Human modifications to the land are another way such features can form. Again, disturbance is the key. Anthropogenic activity has the potential to disturb the land as much or more than some natural processes. Deforestation, development, slash & burn agriculture, acid rain, and climate change are but some of the human impacts that can help strip the natural protective layer of vegetation from the surface and exacerbate erosional activity.

The key difference between the east and west is the drop in average annual precipitation once you cross the 100th meridian. West of that line, the lack of water and/or unequal distribution thereof actually becomes a major factor in the fluvial processes that shape the land. It sounds like a paradox and it is to some degree. But the lower the annual precipitation totals are in any given area, the higher the variability of precipitation will be. What this means in practical terms is a cycle of drought and deluge for areas like Quatal Canyon. Large parts of California fall into this category.

So why are they here, precisely?

Quatal Canyon is a major drainage/tributary of the Santa Maria Watershed. The intermittent streams that currently course though this semi-arid region rise on the WSW slopes of nearby Mt. Pinos. According to USGS survey maps, much of the surrounding area and valleys are underlain with Quaternary, sedimentary rocks. Sedimentary rocks, while not as crumbly as unconsolidated sediments, still weather and erode faster than most igneous or metamorphic rock. At some point in the past, a sizable amount of clay, silt, and sand was transported and deposited by fluvial processes in the streams or perhaps in a shallow lake that once existed here. These formations were then buried by more resistant layers and covered with vegetation before becoming exposed once more to the elements. That exposure may have been from a disturbance, natural erosional processes, or tectonic activity or some combination thereof.

Okay, maybe not N.Y. but what does this have to do with Utah?

The coloration of these rocks (orange, white and reddish hues) and the minerals they contain (iron oxides, mostly), coupled with the spectacular shapes they take on (spires, hoodoos and pillars) are what make this area reminiscent of the fantastic lands of the Beehive State. Obviously this smallish formation of a few hundred acres in Quatal Canyon can’t compare to the sweeping grandeur that is to be found in Bryce Canyon National Park. But in the hidden recesses and folds of this formation, you can find places that look strikingly similar. The processes are more or less the same.

Owing to the elevation (~ 4,000’/1219m) and the inland location of Quatal Canyon, much of the vegetation that surrounds the badlands is also very similar to that of the Great Basin Province: pinon and juniper woodlands. With some carefully chosen angles, I’ve fooled even knowledgeable people about the exact location of these features. Then again, the Golden State is well-known as a stand-in for many other exotic locales across the globe. Hollywood has made an industry of that fact.

More than meets the eye …

Badlands, as it turns out, are also a good place to teach about drainage patterns.   The lack of vegetated cover combined with soft sediments means that rainfall doesn’t flow overland very long — and you can easily see its effects.   Here, surface runoff quickly starts carving small rills and gullies in the loose ground.  Also, with no vegetation to help shield from and soak up precipitation events, the ephemeral streams that form in these lands can more quickly become erosional torrents. These patterns are easily discernible here even to the untrained eye.

In turn, the geology and geomorphology are laid bare in such places. It is not hard to identify such things as tilting, folding, or warping in the clearly visible stratified layers. Teaching such subjects in my native Connecticut would be more difficult by virtue of the fact that — barring a few rock outcrops here and there — trees and grass cover everything of interest. That is obviously not so in the more arid regions of the west. The dearth of ground cover means the minerals and mechanisms that make up landforms are more easily exposed to the eye and the rock hammer.

There are much more extensive areas of badlands to be found in California. Perhaps the largest cluster is a discontinuous assemblage in and around Anza-Borrego State Park. Those badlands are measured in square miles, not acres. Portions of the Mecca Hills near the north end of the Salton Sea also exhibit some badlands topography.  Probably the most sublime examples can be found in the Golden State can be experienced at Zabriskie Point in Death Valley National Park.

More than anything, badlands are just really cool to look at! 

Though I have lived in the Golden State now for some 20 years, I still can gaze out upon the scenery here with “Eastern Eyes.” To my gaze, badlands are one of the most exotic and awe inspiring landforms I can think of. And in knowing a thing or two about geology and geomorphology, they speak to me of a changing Earth, the passage of time, and beauty that is the natural world.

There is nothing bad about them at all.

The post Badlands In a New York Minute? first appeared on Rediscovering the Golden State.

It was dinnertime when serpentine seismic waves suddenly began rippling and then rolling through our creaking house. We watched and braced ourselves as the light fixture hanging above the trembling dinner table began swaying, as if to dance in choreography with other objects that were not solidly secured. Seasoned Californians who have experienced too many tremblors over the decades recognize these seismic waves, lasting several seconds or more, as eerie messengers propagating from a strong but distant earthquake, perhaps hundreds of miles away. This version of California vertigo is quite different from the short jolts and lurches of smaller quakes originating from nearby epicenters. Thankfully, the undulations subsided several seconds later, leaving little or no damage here, so that we could connect to the best media to answer our questions: How big was this one, who and where were the latest distant victims, and could we expect more or even greater terra convulsions? Thanks to technologies scientists have developed in recent years, and we have explored in previous stories on this web site, the answers came within minutes, a mere instant compared to the hours of anxious anticipation that would pass after sizable earthquakes in past decades. 

Though some shaking was felt as far away as Sacramento and San Diego and Las Vegas, the epicenter and greatest damage was located in the sparsely populated desert about 120 miles (195km) north of major southern California cities. Their seclusion could not spare the victims of small communities around Trona and Ridgecrest or the Naval Air Weapons Station at China Lake from violent shaking that cracked buildings, set fires, crumbled walls, threw mobile homes off their foundations, and destroyed infrastructure until more than $1 billion damage was done. It would be recorded as another powerful earthquake, but perceived as another case of how most Californians dodged the dreaded “Big One” bullet. 

This was the largest (M7.1) in a series of earthquakes that fractured and violently shook the mostly remote desert floor of Searles Valley and the adjacent rugged desert mountains to its west during the first week of July 2019. It was also the largest earthquake to hit within the borders of California in two decades. Interestingly, the Hector Mine earthquake of 1999 and the Landers quake of 1992 were similar temblors just above magnitude 7 that also sheared dramatic cracks and horizontal and vertical displacements of several feet on the desert floor to the south; they also tore through remote desert regions, sparing distant population centers from major damage. An image in our publication shows this author standing next to a vertical fault scarp of more than 6 feet (2 meters) high, lifted in less than 30 seconds by the Landers earthquake. These major seismic events in our remote deserts contrast with the disastrous and deadly 1989 Loma Prieta quake (M7.0) in the Bay Area and the 1994 Northridge cataclysm (M6.7), two of the most costly natural disasters in U. S. history up to those times, both with epicenters under or near major cities, but both leaving less conspicuous surface fissures that were a lot more difficult to find and measure. 

Scientists named these more recent July 2019 tremors the “Ridgecrest Earthquake Sequence”, including that largest July 5^th M7.1 event described at the start of this article. It was preceded by a major foreshock of M6.4 about 34 hours earlier, which had likewise been preceded by a series of smaller foreshocks. That first big M6.4 tremor on July 4, and its foreshocks, activated a southwest-northeast-trending fault across Searles Valley, causing noticeable left-lateral displacements. The larger M7.1 main event and its aftershocks spread along a northwest-southeast-oriented fault with dramatic vertical and even more dramatic right-lateral displacements on the desert floor that were locally greater than 12 feet (>3.5 meters). These two perpendicular faults cross in Searles Valley; the complexity of these displacements resembles major geologic structures in the region. They are all part what geologists have labelled the Eastern California Shear Zone.

Just to the south of Searles Valley, the east/northeast-trending Garlock Fault (transverse to most other California geologic structures) is the most dramatic left-lateral feature on the state’s landscapes. A series of aftershocks were measured along this Garlock Fault as part of this sequence that started with left-lateral faulting in the Searles Valley. In contrast, north and northwest of Searles Valley are the numerous Basin and Range horsts and grabens of uplifted rugged mountains and down-dropped desert valleys cut along more common right lateral and vertical faults that trend north into the Basin and Range’s Death Valley, Panamint Valley, Owens Valley, and their adjacent mountain ranges. The main 7.1 earthquake (more aligned with tectonic activity and geologic structures common to the north) was followed by aftershocks that eventually rippled all the way up toward Olancha and the Owens Valley, which is also being dropped down below the dramatic vertical faulting that lifts the eastern Sierra Nevada Mountains. You might imagine how extensional forces are tearing at the crust in this region as the Pacific Plate to the west shears toward the northwest and away from this western edge of the North American Plate. And so, there is Searles Valley, at the northern edge of the Mojave Desert and the southern edge of the Basin and Range, being broken by tectonic forces common to two major physiographic provinces.

Such recent and ancient tectonic activity has lifted adjacent and more distant mountain ranges above a downwarped Searles Valley. An amazing mélange of rock formations many millions of years old have been exposed on these desert mountain slopes. Those rocks with their assorted chemistries continue to weather and crumble into smaller pieces that can be transported by wind or the rare downpours that will deliver mud and debris flows through desert canyons and into the valleys. These materials are further broken down into finer sediments and dissolved chemicals that can be deposited on valley floors. With no outlets to drain these inland basins, they are stranded and often baked into desert playas with their high concentrations of salts. 

But it hasn’t always been so dry here. More than 11,000 years ago, when the climate was cooler and wetter and glaciers were carving the distant Sierra Nevada, a chain of Pleistocene lakes connected many of these desert basins. You can also learn more about them in our publication. Searles Valley filled with more than 600 feet (about 200m) of water. These inland lakes would eventually vanish as conditions evolved into the warmer and drier periods that ended the Ice Ages and characterize today’s climates and landscapes. Thick layers of minerals were precipitated as the trapped waters evaporated over thousands of years. Brief wetting and shallow flooding during occasional wet periods delivered and concentrated more minerals into these desert basins to be dried and baked. These carbonates, sulfates, borates, and halides rich in sodium and potassium have encouraged commercial mining operations here ever since prospector John W. Searles recognized their value. Searles established the San Bernardino Borax Mining Company in the 1870s and gained attention for using his mule teams to haul borax out of Searles Valley, through Salt Wells (AKA Poison) Canyon, so that it could eventually be delivered all the way to San Pedro.  

After Searles’ death and throughout the 1900s, mining companies that operated in this valley evolved through good and bad times with different owners and names. The small company town of Trona also grew as the railroad made it more accessible since the early 1900s; the highway (today’s 178) made further connections. By the mid-1900s, Trona had become a mining boom town with a population soaring over 6,000. Today, Searles Valley Minerals continues to pump brine from below the mostly dry lake so that it can be processed into an astonishing variety of tons of valuable mineral products that include borax and boric acid.

And it’s not all about work. More than a thousand mineral and geology enthusiasts flood the valley during the annual October Gem-O-Rama, when Trona and surroundings are packed with excited visitors who participate in field trips sponsored by the Searles Lake Gem & Mineral Society. The few small local museums, stores, and eateries become the center of at least 36 hours of fame when folks show and share their rock and mineral and lapidary arts collections, and venture out on the playa. They are guided to collect spectacular crystals that include some of the finest samples of six-sided hanksite in the world and beautiful specimens of pink halite that have been stained by salt-loving bacteria. These annual gatherings are advertised as the most exciting mineral collecting field trips in the U.S. (After more than 75 years of tradition, these treasure hunts were temporarily cancelled in 2019 due to lingering infrastructure damage from the earthquakes, and scratched again during the 2020 COVID-19 pandemic.)  

We can appreciate that had it not been for the tectonic activity that has been dropping and isolating these desert basins and lifting surrounding mountain ranges, these mineral-laden desert playas would not exist. It is more than ironic that the seismic activity of July 2019 we examine here had visibly damaged one of the tall Searles Valley Minerals chimneys that erupt as dominant landmarks above this valley, as if humans were trying to recreate the nearby Trona Pinnacles.

The July 2019 Ridgecrest Earthquake Sequence even knocked a few of the more precarious rocks and boulders down from those Trona Pinnacles across the valley. This is a roughly 15-square-mile accumulation of tufa spires that rise over 100 feet above Searles Dry Lake. These towers that define natural landscape oddities were forming more than 11,000 years ago as underground springs transported calcium up to meet the carbonates that were becoming more concentrated in the evaporating inland lake. Algae bonded to these calcium carbonate deposits, growing the tufa reefs that emerged as the drying and warming climate finished off the lake. (You might notice some of the stranded ancient shoreline contours, or strandlines, along slopes that ring the valley.) As a National Natural Landmark, the Trona Pinnacles have earned recognition from landscape admirers and gained attention in the numerous movies and TV productions that have exploited them, often as background scenery to simulate the topography on other planets, at least in our imaginations.

We can also blame tectonic activity for building the Coast Ranges and Sierra Nevada Mountains to the west, as they have been blocking moist air masses that would otherwise invade from the Pacific and bring precipitation and accumulated runoff that might dissolve and dilute these mineral deposits.  As with other California desert basins, air masses can only invade Searles Valley by flowing down the very mountains that have already wrung out moisture from otherwise promising storms, resulting in more compressional heating and drying by the time they reach the valley floor, at about 1,700 feet above sea level. With average annual precipitation below 4 inches (<10cm), exceptionally low specific humidities, and relative humidities frequently below 10%, this alkaline dust bowl remains nearly as dry as Death Valley and one of the driest places on Earth. You can also thank the dry continental air masses for summer daytime high temperatures that average well above 100 degrees and overnight lows in winter that average around freezing. Winter’s coldest storms can even deliver a rare dusting of “dry” snow. Abundant sunshine rules year round, but radiation escapes quickly and temperatures usually plummet after sunset. Add the occasional fierce winds and you have classic desert extremes that many people, plants, and animals may consider hostile.

And so it is not surprising that the plants and animals that survive around here must be adapted to extreme aridity and the wild variations in radiation and temperature. Although you may encounter Joshua Trees and other high desert woodlands while climbing into cooler and more moist surrounding mountains, the valley is only decorated with the most resilient desert scrub (such as desert holly) and brief spring wildflower blooms. As you approach the floor of the valley, limiting factors multiply, as only the most salt-tolerant plants can survive in what becomes an increasingly toxic soil. Parts of this desert erupt with activity during the brief spring blooms that can attract many animal species. These include a wide variety of insects, various herbivores, and their predators. Ravens, prairie falcons, and peregrine falcons may soar above horned lizards, desert iguanas, kangaroo rats, desert tortoises, coyotes, and kit foxes. Some species, such as falcons and tortoises, are highly sensitive to human disturbances in these fragile ecosystems. Please remain especially distant from falcon nests, as they are often built in the very cavities that people enjoy exploring.

Beyond social media, today’s Searles Valley and its Trona is connected to the world mostly through the many human passersby on Hwy 178 who are headed for Death Valley National Park or other popular ecotourist hot spots. Still, more powerful global connections exist that may not, at first, be as evident in this isolated desert town. The dominant company (Searles Valley Minerals) is a subsidiary of a major international corporation as it ships tons of mineral products each day to California ports and then to at least 52 different countries. The community is dependent on this company that provides necessities for its residents and employs more than 700 people. Many of the other families are anchored by workers who provide essential services in this company town.

After the July 2019 earthquakes hit, Trona’s people (less than 2,000 within census-designated Searles Valley, but thousands more in surrounding communities) and its schools and its cultures were thrust into the national and global spotlights. Clamoring for the latest compelling stories, national media converged on and then unveiled what some popular culture urban observers considered foreign or unimaginable, as folks weighed the advantages and disadvantages of living in such seclusion. For instance, it was shown that roughly 250 students populate the Trona Joint Unified School District that includes one elementary and one high school. When the local high school (The Tornadoes) football team gained praise for training on the only known all-dirt field in the nation, the power of limitations quickly became apparent. The harsh climate and high salt content in the soils and the lack of financial resources eliminated traditional turf options on what became known as “The Pit.” Unreliable attendance from the small pool of young athletes necessitated 8-man football. As unlikely students and other locals were interviewed, a common thread emerged: the kids and adults here are tough and their resilience would carry them through earthquake recovery in this place that requires adaptations to limitations.

The power of social media continues to add to the push and pull factors that tempt young people and others to move out and on, toward what they may perceive as better and more exciting opportunities. It certainly is not the booming mining community that grew to over 6,000 people in the mid-1900s. But you will also find great pride within the people and cultures that have developed in this community. You don’t see locals running on the endless treadmills that torture California city dwellers struggling just to make ends meet so they can pay rents or mortgages that rank highest in the nation. Here, the average cost of a home is well below the national average; you can still buy a modest house on a large lot for less than $100,000. There are multiple apartments and small houses around the greater region (that includes Ridgecrest) renting for less than $1,000/month. Seismologists and engineers have already used some of them as examples of how modern earthquake building codes kept damage and losses in the region much lower in the relatively new construction, compared to the oldest structures. The result is more housing inventory remained after the earthquakes so that fewer people were tempted or forced to move on to those other horizons and opportunities. 

This dusty, solitary place feels perfectly separate and disconnected from the mild climates and overcrowded, unaffordable giant urban centers closer to the coast, on the opposite sides of the great California ranges. Searles Valley may even appear other worldly to urban dwellers celebrating their popular cultures. Here is where primary extractive industries fuel a different kind of economic system where the cost of living and household incomes remain well below the state average. It’s easy to find peace and quiet, there are more than enough bright stars to count at night, and a wealth of desolate, crystalline desert and mountain landscapes call out to the adventurer. Life is slower paced within these more traditional cultures where neighbors know one another and people may live and celebrate “Trona Strong.”

Searles Valley and other remote places may define the other California, but they are powerfully connected to the world and to rest of us by a lot more than natural resources, the chemicals we use each day, and social media. These connections become especially evident when seismic waves ripple through our communities from another distant and different place. They will announce the latest earthquake that is building mountains and rearranging landscapes and creating new victims of the very powerful forces that continue to sculpt such a spectacular and diverse California. Nature will connect us whether we like it or not. We wonder: which landscapes are soon to be rearranged and who might be the next “victims”?

This story was informed by scientists from the United States Geological Survey, Seismological Society of America, Southern California Earthquake Center, California Geological Survey, Bureau of Land Management, and the Searles Lake Gem and Mineral Society. 

A few other sources:

View this short video about Trona, created by ghost towns and mines enthusiast Ray Dunakin, just three weeks after the earthquakes:

Here is the Bureau of Land Management introduction to Trona Pinnacles: https://www.blm.gov/visit/trona-pinnacles

Here is information about the Searles Lake Gem and Mineral Society’s Annual Gem-O-Rama Field Trips: http://www1.iwvisp.com/tronagemclub/General-info.htm

Check out the Kim Stringfellow’s Mojave Art Project and her coverage of the annual Gem-O-Rama on KCET:
https://www.kcet.org/shows/artbound/gem-o-rama-mojave-playa-interventions-part-ii

The post Desert Quakes and Ancient Lakes: Geopostcards from Searles Valley first appeared on Rediscovering the Golden State.

This is certainly NOT the case around Los Angeles, where the city was destroyed in the fictional 1997 Hollywood film, Volcano, since there is no volcanic activity or threat near L.A. today. That movie’s makers had to refabricate the entire geologic dynamics of southern California to make their imaginary volcanic bomb. Here, we take you to northern California’s hot spots to survey the tremendous diversity of active and recently active volcanic landscapes that might remind you more of Washington State or Yellowstone.

We know that each natural hazard poses relative threats or dangers compared to other hazards. For instance, it is certainly true that the earthquakes we have researched in our publication and this web site represent greater potential threats to our state than volcanic eruptions. (It is likely that California will suffer at least one deadly, devastating, and possibly catastrophic quake within the next 30 years.) And we have reported on the deadly fires that have terrorized and even destroyed California communities in recent years. We also recognize that most Californians do not suffer from natural disasters of such frequency and severity as the less fortunate who live in less developed regions of the world. But this story offers another chance for us to appreciate the simultaneous beauty and danger produced by the awesome natural systems and cycles that define our living Earth. Here, we celebrate advancements in science that help prove how our knowledge of nature equals power in this latest version of beauty and the beast.       

This story does not focus on the parts of southern California exhibiting volcanic landscapes that were either recently formed in geologic time or remain active today. Some of these weathering in the Mojave Desert include a chain of ancient volcanoes from Barstow to Amboy. Pisgah and Amboy cones are only thousands of years old and sit atop a variety of lava flows, channels, and caves; at first glance, they appear so fresh as if they could have erupted a few years ago, until you examine more closely. Five young pumice and obsidian domes south of the Salton Sea have erupted among the transform faults and pull-apart basins that help define the thin crust of the Imperial Valley. Gurgling mud pots and active mud volcanoes remind us why this area is listed as one of the higher volcanic eruption threats in the state, as it produces its share of geothermal energy. The Coso Volcanic Field around the southern Owens Valley (including conspicuous Red Hill cinder cone and Fossil Falls adjacent to Hwy 395) and Ubehebe Craters in northern Death Valley are less likely threats also surveyed in our publication but also too far south for this story.       

Here, we consider northern California’s active volcanic regions that earth scientists and geophysicists consider to be high or very high risks. We can now lean on research being done by some of the best geologists and volcanologists at the United States Geological Survey’s Volcano Observatory. These experts recognize the same general volcanic regions we have been researching and reporting on during our project’s more than 20 years. They confirm that, though California’s volcanoes are distant from major cities, nearly 200,000 people are at risk each day, and many millions more pass into and through their sprawling danger zones each year. We are also reminded how these active volcanoes have built some gorgeous and even stunning landscapes that beckon us to reconnect with nature.

Long Valley Volcanic Region and Mammoth Mountain

Riding the ski lifts up Mammoth Mountain, you can look down into the giant bowl below that is Long Valley Caldera. This massive caldera formed nearly 800,000 years ago when a cataclysmic eruption blasted volcanic ash and cinder that would settle in thick layers on surrounding landscapes, while it blew traces of the catastrophe as far as the Great Plains, before collapsing. It is just part of what geologists have labelled the Long Valley Volcanic Region that has been active for about 4 million years, leaving imprints on the landscape that stretch for many more miles.

For instance, Mammoth Mountain is a series of accumulated and overlapping lava domes that date back about 50,000-100,000 years and it is considered a moderate threat. But today’s active hot springs, fumaroles, and volcanic gas emissions remind us that a turbulent magma chamber waits shallow below the surface for its next return to the stage. The most recent volcanic activity around the base of Mammoth Mountain is only about 8,000 years old.

This region stretches north more than 20 miles toward Mono Craters and into Mono Lake, where the most recent eruption was only about 300 years ago. This is why geologists estimate the Long Valley Volcanic Region to be at very high risk, with a 22.5% chance of experiencing an eruption of some sort in the next 100 years. And that is most likely to occur somewhere around the young Mono Craters that experienced eruptions only about 680 years ago.

In 1980, curiously during the infamous Mt. St. Helens explosions in Washington, ground swelling was measured and a series of moderate earthquakes rolled through the region, doing some damage, as a magma chamber was measured squeezing its way toward the swelling surface. That eruption never saw the light of day, but officials have made sure there is more than just one emergency exit route off Mammoth Mountain, just in case.

In the next two images, we will take a brief break from our active, high risk volcanoes to show a peculiar ancient volcanic landscape (Sutter Buttes) that pops up from the Sacramento Valley.

Clear Lake and Geysers Volcanic Area

A volcanic region around 100 miles north of San Francisco stretches from The Geysers north into Clear Lake. Geophysical surveys reveal a mass of partially molten rock below this region with a larger magma chamber below that. This region is dotted with numerous hot springs and fumaroles (discharging steam) that start in our most famous wine country and stretch north from Sonoma and Napa Valleys all the way to Clear Lake. The hot springs start as rain water that seeps deep into hot rocks until it heats under pressure (more than 350 degrees F at one mile deep) and finally erupts to the surface.

The Geysers region’s natural fumaroles originate in shallow cavities only a few hundred feet deep. A host of geothermal companies drilled into much deeper reservoirs up to two miles until they tapped the sources dry by 1990. There is still enough activity to boil residual heat water that has seeped through underground fissures, especially in the Mayacmas Mountains. The Geysers Resort and geothermal power plants are east of Cloverdale. These wells are some of the largest geothermal energy producers in the world, producing enough energy for a city of more than 500,000 people with the potential to send power to up to 900,000. The lack of corrosive chemicals in the dry steam contributes to a more efficient energy source. You will find California’s Old Faithful Geyser southeast of this area, near Calistoga.

There may be only about 1,000 geysers on Earth that episodically discharge water and steam. California’s Old Faithful is what remains of more than a dozen wells in the area that were pricked by the 1930s to release fountains of water and steam to attract tourists. Here again, groundwater accumulates and gets superheated up to 350 degrees F until it erupts under pressure. Old Faithful’s cycle may shorten to only about every 5 minutes after heavy winter rains, but can lengthen to every hour or so during dry autumns. It has been touted as one of only three “faithful” geysers on Earth.

The north end of this volcanic field is around Clear Lake. During its roughly two million years of activity, most eruptions here have not been particularly violent, though eruptions through the lake around 11,000 years ago involved flash vaporization of water. The most notable landmark is 300,000-year-old Mt. Konocti, with its five peaks up to 4,300 feet asl and the nearby younger shoreline craters and cinder cones that date back to those more recent flash eruptions. USGS scientists continue monitoring gas emissions, the dozens of annual seismic events on southern flanks of the lake, and thousands of earthquakes that shake the entire region each year.

Left behind are a wide variety of rocks to admire. Chemically-intermediate andesite dominates, but with occasional smatterings of rhyolites and basalts. Pyroclastics and lava flows cover hundreds of square miles in the Coast Ranges’ Sonoma, Howell, and Mayacmas Mountains, including the broken rhyolites of Mount Saint Helena.

Medicine Lake and Lava Beds

Medicine Lake is located in far north-central California, just south of and adjacent to Lava Beds National Monument. It is part of the Cascades system, erupting from magma that forms deep below the surface as the Gorda oceanic plate is subducted below the North American continental plate in the Cascadia Subduction Zone. Underplating is another term often used to describe the denser ocean plate grinding into and incorporating pieces of the overriding continental plate as it is thrust under it. We examine this plate tectonic geology more thoroughly in our publication.

This Medicine Lake region has a wider assortment of eruptions and rock chemistry compared to most other great Cascade volcanoes. The voluminous foundation of Medicine Lake volcano was built during approximately 500,000 years of effusive eruptions that poured out extensive runny lava flows, Hawaii style (containing abundant darker, heavier iron and magnesium with very high melting points). However, those older basalts grade toward more recent rhyolitic (felsic), viscous eruptions that have been more violent. Seven of the ten eruptions during the last roughly 5,000 years have included ash clouds and thick, glassy lava flows and those include Little Glass Mountain and Glass Mountain around 1,000 years ago. Medicine Lake is listed as a high risk volcano.  

The top of a much larger volcano collapsed up to 5 million years ago, leaving a giant caldera to be filled with younger lava flows. Today’s 8X14- mile caldera containing Medicine Lake is labelled a water-filled collapse basin. Partially molten rock remains below the volcano, fueling geothermal activity.

The many types of eruptions from Medicine Lake during the last 500,000 years have also spread a wide variety of volcanic flows across Lava Beds National Monument that include cinder and spatter cones and nearly 700 lava tube caves. Since geophysicists estimate there is about a 1% chance that there will be an eruption within the next 30 years, it is considered a relatively high risk region.  

We will now take another brief break from our more hazardous, active volcanoes to view ancient volcanic landscapes common to the Modoc Plateau. You will find them between and east of the Cascades’ Shasta and Lassen.

We now turn our attention to the two most magnificent and majestic California volcanoes (Shasta and Lassen), both of the southern Cascades and both listed as very high risk.

Mt. Shasta

It is the giant ice- and snow-covered dome that dominates the horizon of nearly every north-central California landscape. It demands your attention whether you are traveling north from Redding or south from Oregon. It is California’s quintessential volcanic mountain and it means business.

Shasta is a classic composite or stratovolcano that was built by a series of eruptions from magma chambers forming in that previously-mentioned subduction zone, as the continental North American plate slides over the oceanic Gorda Plate. Continental crust is melted and incorporated into the magma as it rises toward the surface, producing relatively felsic (rich in light-colored silica, poor in darker and heavier iron and magnesium), viscous eruptions that can be catastrophic. At nearly 14,170 feet above sea level, the current summit has grown to replace a cataclysmic collapse and record-shattering landslide that devastated Shasta Valley toward the north more than 300,000 years ago.

More recently, the smaller Shastina dome (attached to the upper west slope of Shasta) and the steep, dramatically-conic Black Butte (pointing up next to Interstate 5) formed during eruptions about 11,000 years ago. Bursts of steam and ash may have been emitted just a few hundred years ago, but scientists date the last official eruption at about 3,000 years. Average eruption intervals of about 800 years over recent geologic history suggest about a 3.5% chance of an eruption in the next 30 years from a deep mass of partially molten material.                 

Geologists inform communities and officials around Shasta and Lassen of potential hazards as they use seismometers and GPS receivers to measure seismic activity and surface deformations to assess future risks. Think of the cataclysmic eruptions from similar composite volcanoes around the world, particularly around the Pacific Ring of Fire. So, if you like to tempt fiery terror that includes killer glowing gas clouds and lahars, this massive volcano’s for you, as it is considered a very high risk.

Most locals are more affectionate, knowing that wherever and whenever they see a big white cone reaching to the sky, it has to be Shasta. They also observe how this 5^th tallest mountain peak in California has influenced local air flow patterns and other weather, such as by forcing air to rise up its slopes to drop the moisture that helped build today’s shrinking glaciers, and how its microclimates support the diversity of plant communities and ecosystems that have adapted to each elevation on each side of the volcano.

Lassen (Formerly Mt. Tehama)

Lassen marks the southern end of the great Cascade volcanoes fed by magma chambers formed within the behemoth Cascadia Subduction Zone previously mentioned. It is also an imposing landmark from many different locations that range from near Shasta, to much of the Sacramento Valley, to the northern Sierra Nevada. Located east of Redding, it looms closer to larger population centers than Shasta and is also listed as very high risk for very good reason.

Though its eruption from 1914-1917 was considered small to moderate by Cascades standards, it belched out the storied 30,000-foot mushroom clouds of ash that were carried and deposited as far as 280 miles east by prevailing winds and viewed by awestruck residents in the Sacramento Valley and beyond. This fiery drama included the apocalyptic pyroclastic flows and lahars, though this time they were relatively smaller than more legendary eruptions from notorious Pacific Rim volcanoes. This recent eruption and the natural beauty that defines Lassen solidified it as one of our National Parks, though it is not as large or overwhelming as a Yellowstone or Yosemite.

Only two other recent eruptions near what is called Lassen Volcanic Center included Lassen’s Cinder Cone about 345 years ago and at Chaos Crags about 1,100 years ago. However, there have been hundreds of various kinds of explosive eruptions throughout the region within the last million years. Many of Lassen’s features sit within what was (more than 300,000 years ago) a much larger andesitic stratovolcano now known as Mt. Tehama or Brokeoff Volcano. It reached to about 11,000 feet and was more voluminous than Shasta before its collapse, leaving only remnants around today’s Lassen that include Brokeoff Mountain. What we see today is one of the world’s largest dacite lava domes that has squeezed up in place of Tahama’s collapse (making it unique among Cascade volcanoes). As might be expected, a deep mass of partly molten rock that fuels today’s geothermal activity lurks below Lassen. This activity includes accessible and colorful fumaroles, hot springs, and gurgling hot mud pots that attract ecotourists and geology buffs. You don’t have to imagine Yellowstone while walking through Bumpass Hell or more easily accessible Sulphur Works.

As with Shasta, seismometers and GPS receivers are measuring any earthquakes and surface deformations that may warn of future eruptions. With about a 0.5% chance of erupting each year, Lassen is listed as a very high risk volcano. The peak stands high over the surrounding landscapes, but it is usually accessible by July to the hardy hiker after winter snow packs have melted down.

As with Shasta, Lassen represents a formidable barrier that reroutes air flow patterns and forces air masses to rise over it. When these air masses cool and condense, they drop copious moisture on the slopes. Subsequent runoff feeds streams that cascade down to lower elevations, nourishing a variety of lush, stunning ecosystems that attract wildlife and more ecotourists.

All of the northern California volcanic areas examined here (except for the Sutter Buttes photos) are considered active volcanoes with molten or partially-molten materials lurking below, while generating volcanic activity at the surface. We hope you have enjoyed learning about these colorful but threatening geologic landscapes that combine to decorate the Golden State. You can find more details about California volcanoes in various publications that have appeared over the years and are listed in our publication. They include stellar, exhaustive works, from general books on the geology of California to handy roadside geology guides. If you want to learn even more about California’s volcanoes and their threats, go to the world’s leading scientists at the USGS Volcano Observatory, who helped inform this story and brought more clarification to some of the information we have presented in this project during its more than 20 years: https://www.usgs.gov/observatories/california-volcano-observatory

For now, we appropriately end this explosive story by completing our colorful tour of Lassen Volcanic National Park.

The post Great Volcanoes of Northern California first appeared on Rediscovering the Golden State.

Recently, a UC Berkeley team of scientists used new technologies that included satellite imagery to show that the creep along the Hayward Fault continued farther south than previously thought. This added to evidence that the Hayward Fault was connected to the Calaveras Fault, which continues much farther southeast past Gilroy. This is more than a technicality: it suggests that this connected structure may be capable of delivering an even more powerful and devastating earthquake to a larger region compared to distinct, individual faults.

By 2017, as the seismic research progressed in northern California, another significant discovery was being made far to the south. Scientists were using a combination of studies to show how stepovers of up to a mile may link what were once considered separate active faults. This research in southern California includes a collection of years of oil company seismic surveys and Scripps Institute of Oceanography seafloor studies.  Scientists found that San Diego’s Rose Canyon Fault was connected to the Newport Inglewood Fault by step overs less than a mile, linking them as one continuous fault. This suggests that the San Diego area is more closely connected than previously thought to the seismic risks that have long been established in the Los Angeles area.  

Read more:

http://news.berkeley.edu/2015/04/02/calaveras-hayward-fault-link-means-potentially-larger-quakes/

http://onlinelibrary.wiley.com/doi/10.1002/2016JB013467/epdf

Another interesting source to learn about the Hayward Fault is Horst Rademacher’s (UC Berkeley) walking field guide: The Hayward Fault at the Campus of UC Berkeley: A Guide to a Brief Walking Tour, June 7, 2017

https://seismo.berkeley.edu/docs/HF_Tour_Stadium-1.1-Protected.pdf

The post New Technologies For Understanding Seismic Risks first appeared on Rediscovering the Golden State.

This arm of the Sonoran Desert is one of the most barren environments in the state. With annual precipitation totals averaging from 3-5 inches in many places, the Colorado Desert has only a sparse covering of vegetation. At first glance, it superficially resembles the view some future astronaut may be treated to upon arrival at the red planet. 

But even that small amount of rainfall is enough to provide evidence that this image is of Earth rather than Mars. Fluvial processes (water based) are the big drivers of erosion on Earth. Whereas on Mars, aeolian processes (wind based) are far more prominent erosional agents. Look closely and you will see dendritic drainage patterns along with associated canyons and arroyos. This is a clear indication that water, however scarce, flowed and shaped this land. Look even closer and you may spot evidence of life in the canyon washes far below.

The post Martian Georphology? first appeared on Rediscovering the Golden State.

Since mountain building and degradation are always occurring simultaneously, recent tectonic activity in this region has uplifted and exposed tremendous rock masses that will be transported to the sea from these mainly youthful, steep, high-energy environments. Geomorphology, biogeography, hydrology, and human impacts are the highlights of this field trip, Landslides, Floods, and Sediment, championed by Andre Lehre, Department of Geology, Humboldt State University, and sponsored by the California Geographical Society in the spring of 2015.

We start at the Salt River, where it struggles past Ferndale through the rich floodplain of the Eel River located south of Humboldt Bay. For centuries here, the Salt meandered toward the Eel, where their waters were finally discharged into the ocean. But in recent decades, accelerated upstream erosion, subsidence, and reduced stream gradients have choked the Salt River with sediment, up to 54 inches of filling within 11 years. Increased sediment yield comes from fresh material exposed on surrounding slopes by recent earthquakes and short-sided land use management that included past logging, agriculture, and other development in the watershed.

Though this Salt River channel has nearly disappeared, frequent flooding and pooling has earned it labels such as “a lot of volume but no velocity” and “tricky hydrology”. That is why scientists and engineers have developed and begun implementing a massive restoration plan for the estuary and river during this century. Folks there are monitoring the progress of this herculean effort (certainly by North Coast standards) that will hopefully restore the fish, ecosystem, and the integrity of the Salt River, while solving the alternating stagnation and flooding problems. As we include two images of this beautiful quagmire, you might consult the most recent updates, starting with the two references we list at the end of this essay.

Next, we take you to the Centerville Beach landslide, named after the nearby town that was already abandoned by 1885. Though the most noticeable part of this slumping debris slide or flow occurred during a wet 1997-98, there is lumpy evidence of ancient slides, and it has shown more recent activity. In the images, note the seeps emerging in the silt and clay sediments of the Rio Dell Formation. In this case, the material is delivered directly to the sea after tectonic activity has lifted it up to 2m (6 feet)/ 1,000 years, very fast uplift in geologic terms. We will now travel inland and upstream to examine how mass wasting is delivering tons of debris into energetic streams and rivers that will then carry the sediment through river valleys and eventually to the sea.

We head south on Hwy 101 toward Humboldt Redwoods State Park to examine streams that flow into the Eel River. Little Cow Creek is an example of a stream closer to equilibrium since its watershed wasn’t heavily impacted by logging. But Bull Creek continues to recover from the mid-1900s clear cutting that devastated these watersheds. An annual tax on the value of standing timber in 1946 coincided with the post WWII building boom to encourage reckless clear cutting and tractor yarding that turned surrounding steep hillsides into skid trails and stream channels into roads. The 1946-1967 logging left devastated hillsides vulnerable to fires, floods, and mass wasting. Violent flooding carried tons of sediment downstream, dramatically widening stream channels that suffered from massive bank erosion and bar formations.

Bull Creek and Cuneo Creek were particularly devastated by the flooding and debris that immediately followed clear cutting of surrounding steep slopes in the 1950s and 1960s. Even the old Bull Creek town site was buried in thick gravel deposits. Cuneo Creek is still recovering from at least 7m (22 ft.) of filling since 1955, as willow and alder return to stream terraces. Meanwhile, nearby Cow Creek and Squaw Creek provide examples of relatively undisturbed watersheds that were not heavily impacted by the logging. Our images illustrate stark contrasts between the accelerated erosion and mass wasting on recklessly logged hillsides versus the relative stability of adjacent less altered watersheds. Perhaps the greatest contrasts can be seen within the oldest redwood forests that are anchored in thick, rich silt, the nurturing alluvium deposited during rare inundating floods from many centuries before humans started logging. Contrast these with images from the steep exposed clear cut slopes such as around Devil’s Elbow Slide lurking above recovering Cuneo Creek.   

This field trip demonstrates how natural and human-induced mass wasting and accelerated erosion carry tons of sediment that is deposited into lower elevations in northwest California. When natural succession is interrupted and the landscape falls out of balance, the results can be costly and dangerous devastation that may require decades or even centuries to mend.

Our story is yet another example of how many different disciplines and fields of study must be applied to understand the processes shaping our landscapes, how humans are impacting them, and to solve the many problems that may result from these complex interactions. In this case, we must use our combined knowledge of geology, soils, weather and climate, biogeography, hydrology, and human geography to understand the systems and cycles that are changing northwest California landscapes. You might consult our book to build your foundation of these concepts as they apply to the entire state. Below we list some relevant references if you would like to continue exploring.  

We must again thank Andre Lehre, Department of Geology, Humboldt State University, and the California Geographical Society for making this exceptional learning experience possible.     

Some references:

• GEOLOGY 700 LANDSLIDES AND FLOODS FIELD TRIP ROAD LOG.
• Salt River restoration gets $1.13 million boost
• The 2008 Salt River Ecosystem Restoration Project report 
• Geology 700: Landslides & Floods in Humboldt County
• Geology of the Humboldt Bay Area 
• From Rivers to Landslides: Charting the Slopes of Sediment Transport

The post External Processes Denude Northwest California Landscapes first appeared on Rediscovering the Golden State.

There is a region in California that experiences more frequent damaging earthquakes and tsunami than anywhere on the U.S. West Coast outside Alaska. It is a region where subduction is still active and catastrophic earthquakes over 8 magnitude are capable of producing tsunami up to 15m (45 feet) high. Entire strips of coastline and even patches of forests have been submerged under water as other landscapes have been lifted higher by these tectonic events that have left recent footprints throughout the state’s northwest coast. This is a region that more resembles the Oregon coast, a region seismologists and geologists label the Cascadian Subduction Zone.

Here, accomplished award-winning geophysicist Dr. Lori Dengler guides us through these broken landscapes on a field trip sponsored by the California Geographical Society in the spring of 2015. A series of buckles and thrusts in the crust are evident here, north of where the north-south trending San Andreas system is cut off by the east-west Mendocino Fault. This Cascadian Subduction Zone megathrust belt runs about 700 miles from Cape Mendocino to Vancouver Island. The plate boundary gently slopes from the ocean floor about 45 miles offshore to about 8 miles below Humboldt Bay, then deeper below the surface farther inland. The result is a youthful fold and thrust belt landscape that includes at least 6 active thrust faults in the Humboldt Bay region.

Each fault breaks with occasional earthquakes that have been thrusting up deformed marine terraces and downwarping the bays and marshes. The greatest events have dropped the bays and lagoons after marsh peats were established during centuries of relative stability. These lowlands are susceptible to liquefaction, soil amplification, subsidence, and tsunami inundation during these spasmodic events. Thick layers of mud and other sediment are suddenly deposited, burying the old peat and building up a new surface where another stable layer of peat can grow. A few more centuries pass until the next mega earthquake continues these cycles that have been correlated in time with similar tectonic shifts along the Oregon and Washington coasts. The last major event (January 1700) was so large, it sent a teletsunami that was still several meters high when it arrived in Japan. There are even Native American (Yurok) stories of how these megaquakes and their tsunami flooded bays in the region before recorded history.

The good news is this tectonic activity has produced diverse and scenic topographic features that give unique beauty to this quiet coast of cool mist. The bad news is there have been 24 tsunami recorded on this northwest coast since 1855, though 19 came from great distances, and Crescent City has suffered more tsunami damage than any West Coast city outside Alaska. And though smaller damaging earthquakes are likely within the next few years, seismologists estimate the probability of the big one at about 15-20% within 50 years. Join us as we explore evidence of these compressional forces and catastrophic events from the top of the thrusts and anticlines into the downwarped lagoons and bays.

Special thanks to Dr. Lori Dengler, Humboldt State University, and the California Geographical Society.

If you are looking for more, consult Chapters 2 and 3 of our book and try these sources:

• Recently completed relative tsunami hazard maps of the Humboldt Bay region
• Relative tsunami hazard mapping for Humboldt and Del Norte Counties, California
• Living on Shaky Ground: How to Survive Earthquakes and Tsunamis in Northern California
• Redwood Coast Tsunami Work Group

The post Chasing Earthquakes and Tsunami in Humboldt County and the Northwest Coast first appeared on Rediscovering the Golden State.