A California Love Letter: It's the Best Geology to be Found Anywhere!

This is the second of some resource materials I have on our college website that are being removed, so I wanted to preserve them. The following is some info I give to my students of my "Geology of California" course. For the majority of these students, it is their first introduction to geology, and their first introduction to the extraordinary state that is their home. For a more complete explanation of each superlative, click on the orange links (down the rabbit hole!). Enjoy!

Highest point in the lower 48 states: Mt. Whitney, 14,505 feet 

Lowest point in the western hemisphere: near Badwater, Death Valley, -282 feet

The deepest canyon in North America (maybe): Kings Canyon, Giant Sequoia National Monument. Hells Canyon on the Oregon/Idaho border may be 19 feet deeper. Maybe...

Largest living things in the world: Sequoia Trees

Tallest living things in the world: Coast Redwoods

Oldest living things in the world: Bristlecone Pines (5,000 years), White Mtns, or Creosote Bushes in Colorado Desert (11,000 years)

My Scottish BBC Interview at a relatively balmy 110 degrees

Hottest Place on the Planet and Driest Place in North America: Death Valley: 134 degrees, precipitation 1.4"/year

One of the Snowiest Places in the U.S.: Tamarack, Sierra Nevada, 76 feet in one year, 32 feet in one month, 37 feet on ground at one time

Highest Waterfall in the North America (no. 7 in world): Yosemite Falls, 2,425 feet

Second tallest active volcano in the U.S.: Mt. Shasta, 14,162 feet

Second most recently active volcano in lower 48 states: Mt. Lassen (1914-21)

Most voluminous volcano in the lower 48 states: Medicine Lake Highland (around 130 cubic miles) in northeastern California

Scarp from the 1872 Lone Pine earthquake

Some of the largest earthquakes in the lower 48 states: 1906 (San Francisco 7.8), 1872 Lone Pine (7.8), 1857 (Ft. Tejon 7.8)

Old oil derrick near the Santa Clarita Valley

One of the more prolific oil and natural gas producing regions in the world: Los Angeles Basin, Bakersfield, and Santa Barbara-Ventura Channel

One of the biggest explosions ever: Long Valley Caldera, 750,000 years ago, 125 cubic miles of ash spread all over the western states as far east as Nebraska and Kansas

McWay Falls at Julia Pfeiffer-Burns State Park on the Big Sur Coast

No other state has the combination of landscapes: Coastlines, deserts, mountains, river valleys and plateaus, due in no small part to the fact that California is influenced by all three different kinds of plate margins: Divergent, convergent and transform. Few places in the world have this kind of diversity.

The San Andreas fault on the San Francisco Peninsula. San Andreas reservoir, from which the fault took its name, is in the foreground.

What would you add to this list???

The Other California: A Bit of the Rarest Ecosystem in SoCal at the North Etiwanda Preserve

 

This is ultimately a story about what may be the steepest mountain in the world (although I cannot yet confirm this). But the story involves a little bit of a journey down memory lane if you can bear with me a bit!

When I was a kid in Ontario, California in the 1960s, we possessed one of those wonderful things that kids don't have enough of today: a big backyard. There was room enough for a big lawn for ball games, large hedges and trees, and climbable walls around the lot. And enough bare ground that a kid could dig nice deep holes, looking for fossils or buried treasures. But what I found when digging those holes was a lot of rocks. Big rocks, cobbles really, of granite and gneiss and schist, although I didn't know those terms at the time. But I did wonder where the rocks came from.

Earth science wasn't much of a thing in my primary education in the 1960s, but I knew enough to think the somewhat rounded rocks came from a river. But there were no rivers to speak of in the Inland Empire east of Los Angeles. I got an education about that in 1969 when the biggest floods in nearly two generations hit the valley. Streets turned into rivers, and numerous houses and buildings were destroyed by mudflows coming out of the nearby San Gabriel Mountains. Nearby Day Canyon recorded an outflow corresponding to 33 inches of precipitation across its small drainage basin in 24 hours on February 25, a state record. 

The perspective of this photo may deceptive; all the road you see here is sloping downhill for the entire 14 miles

And then, in the 1970s, it was high school and the cross-country team. A favorite training route was to run up Euclid Avenue in Ontario and Upland (AKA State Route 83). It still is one of the prettiest city roads in the state, with a wide median planted in Pepper Trees and numerous architecturally distinctive homes dating from the early 1900s. It runs for 14 miles in a straight line from San Antonio Heights to the Chino Hills. 

On the easy days we needed only to run a four-mile out-and-back practice to Foothill Avenue, but when the coaches were bearing down, we needed to run all the way up to Baseline or further (6-8 miles). The thing is, the farther one ran up the hill, the steeper it got. Thus was my introduction to the geometry of alluvial fans. During the mudflows and flashfloods that produce the fans, the coarser debris drops out first, and finer-grained materials get carried further out into the plains below. A fan has a concave profile, becoming steepest at the top. 

Some days, the coaches would drive us up into the barrens at the top of the fan, and our runs included a series of breathtaking terraces (and I mean this in the literal sense, as we were breathless by the time we climbed them). I had no idea at the time why they were there. It seemed like alluvial fans should have a smooth profile, not a terraced one.

In the late 1970s I was in college, and my education about alluvial fans and earthquake faults became a bit more complete. These alluvial fans that I had exhausted myself on during cross-country practice were textbook examples of alluvial processes, and maps of them were indeed a part of my laboratory exercises. I also learned that the terraces were actually fault scarps, produced in the last few thousand years by titanic earthquakes that have been lifting the San Gabriel Mountains. They've been uplifted so rapidly that the mountain ridge that includes Ontario and Cucamonga Peaks may be one of the steepest mountain slopes in the world (I heard this statistic at a conference, but I have not been able to locate the reference). The mountains are so steep that mass wasting is a far more dominant form of erosion than river flow. And the mountains are indeed massive, rising 7,000 feet from their base to the highest peaks.

Thus it was that when I left the region in the middle 1980s, the cities below were growing, but the alluvial fans above them had defeated attempts at agricultural development (the lower slopes were ideal for vineyards and citrus orchards). The surfaces were ignored, or used for garbage dumping, shooting, and off-road vehicle travel. They were considered wastelands. Someone had had the bright idea of putting Chaffey College up there, miles away from the main population centers in the valley (it's visible in the lower left corner of the map above), but the college stood apart, surrounded by scrublands.

Sometimes, the lands that seem so barren do in fact have value, and the more they disappear, the more precious the remainder becomes. So maybe it is a good time to ask: what are alluvial fans good for anyway? Here are my thoughts in no particular order:

Artesian wells near San Bernardino in the early years of settlement. Source unknown, but found at you have water mail: artesian wells in San Bernardino, California

Alluvial fans are a vast sponge that could hardly be designed better to capture water and store it underground, safe from evaporation. The Inland Empire became an agricultural powerhouse in the last century on the basis of the citrus fruit industry. It was a desert climate that very rarely froze, and yet had a wealth of water underground. Sometimes at the distal end of fans, artesian springs produced fountains of water that could be easily utilized in the vineyards and orchards (artesian springs and wells are those that flow due to underlying pressure and don't have to be pumped to bring water to the surface).

Urbanization robs much of the fan surface of the ability to absorb water, given that pavement and buildings tend to shunt floodwaters into the concrete flood channels. They in turn are designed to carry water downstream without damaging buildings. If they have enough capacity, that is.

The south slope of Cucamonga Peak, Can anyone see a viable climbing route? I don't think chocks and pitons would work in the rotten rock, but I suppose you could anchor to the trees. That's how I climbed a similar (but shorter) canyon in my youth.

Alluvial fans are a buffer from huge mass wasting events. The mountains above the Inland Empire are, as pointed out previously, among the steepest mountains on the planet. In addition, the rocks that make up the steep cliffs are badly fractured and jointed from the intense faulting and pressure resulting from their uplift. I can't find many records of people climbing the mountain from the south other than up a ridge after a wildfire had cleared the brush. These slopes are exceedingly unstable, and landslides and slope failures are a constant hazard. 

The Blackhawk Slide on the north side of the San Bernardino Mountains. Credit: Kerry Sieh of the U.S. Geological Survey

It may be an extreme example, but the Blackhawk Slide on the north side of the nearby San Bernardino Mountains is a gigantic debris avalanche that traveled 5.6 miles across the surface of the alluvial fan about 17,400 years ago. It was probably set off by a large earthquake, and traveled on a cushion of compressed air. Such huge events are extremely rare, but not out of the realm of possibility.

Mudflows are also considered a form of mass wasting, and the upper parts of alluvial fans are the danger zone for the flows containing the largest boulders (which can be ten feet or more across in extreme instances). 

Mudflow that followed wildfires in the San Bernardino Mountains in 2004. Courtesy: U.S. Geological Survey

Wildland-urban interfaces are a rising concern as urbanization spreads into once wild landscapes. Among the greatest concerns are the incidences of wildfires spreading into cities because of their proximity to chaparral-covered slopes. I'm not speaking as an expert here, but it seems to me that alluvial fan surfaces are a more defensible surface than rugged slopes. Housing developments that butt up against the hillsides would seem to be in the greatest danger in our new normal of drought, rising temperatures and increasing wildfires.

Finally, alluvial fans are a unique and rapidly disappearing ecosystem. The alluvial fans hosted a wide variety of shrubs, grasses, and wildflowers, along with excellent habitat for all manner of mammals, birds, reptiles, and amphibians. Some of the Southern California species are found nowhere else in the world. This rare ecosystem has a name, the Riversidian Alluvial Fan Sage Scrub (RAFSS). It is limited to the alluvial fans along the southern exposures of the Transverse Ranges, including the San Gabriel, San Bernardino, and San Jacinto Mountains. Those fans are as much as 90% urbanized now. There is very little of the original landscape left.

Satellite image of the alluvial fans north of Interstate 210 at Upland and Rancho Cucamonga. The blue marker shows the location of the North Etiwanda Preserve

And so we come to the present day. I returned to the landscape of my youth on a trip last week, and the changes were astounding. I knew that urban development had been creeping up onto the fans, but I never had a good look at the magnitude of the changes. Housing developments and shopping centers have swept up like a tsunami onto the upper reaches of the alluvial fans. Chaffey College has been engulfed by the wave of development and is surrounded by housing tracts.

Despite my dismay at the magnitude of urban development, I found out that a significant portion of the RAFSS has been preserved as the North Etiwanda Preserve. The relatively recent extension of the 210 Pasadena Freeway into San Bernardino had destroyed a significant part of the RAFSS, and as mitigation, 762 acres were given to San Bernardino County for preservation in 1998. Other land acquisitions brought the size of the preserve to 1,176 acres (nearly two square miles). Even better, the lands preserved were contiguous with the slopes leading up Cucamonga Peak, providing an intact ecosystem connected to the nearby trees and chaparral of San Bernardino National Forest.

A three mile long trail winds through the preserve, with numerous interpretive signs detailing the geology, biology, archaeology and recent human history of the region. I didn't have time to walk the entire route, but I was able to see (to my tectonic delight) a perfectly pristine fault scarp running across the preserve. You can see the terrace in the pictures above and below. The last major earthquake probably happened one or two thousand years ago, and may have ranged as high as magnitude 7.5.

Cucamonga Peak is a southern California treasure, a fact not always appreciated by those who live on the alluvial fans below. It is a dangerous neighbor as well, with earthquakes, fires, and floods a serious concern. The North Etiwanda Preserve is a wonderful resource for learning about this unique landscape, and is one of the few places where one can get a sense of the landscape that existed before urbanization swallowed it up. 

On a final note, when I was at Chaffey College in 1976, the geology department got a call from a gravel quarry just east of where the preserve is today. They had found a bone of some sort. It turned out to be a fragment of a tusk from a Columbian Mammoth, one of the many megafauna species that wandered these alluvial fans during the last ice age (although no glaciers came close to this place). One could almost imagine the Columbian Mammoths, Dire Wolves, Sabertooth Cats, Giant Ground Sloths, Short-faced Bears, Horses, and Camels that once roamed across Southern California while strolling the trail at the preserve.

For more information about the natural history of the North Etiwanda Preserve, check out this website at the The San Bernardino County Museum (sbcounty.gov).

This post is part of The Other California blog series I've been writing since 2009.

The Other California: What to See When You've Run Out of Postcard Destinations (Reprise)

(published by Scope Enterprises, Inc)

My earliest blog project was an exploration of the geologically interesting places in California that don't always show up on the postcards (the earliest post is here). I've been working on this project off and on for a dozen years. If you've followed my blog at all, you know I have a type of Geologist Attention Deficit Disorder Syndrome (GADDS), that as soon as I start concentrating on one subject, something interesting pops up somewhere else, and I explore it for a few weeks, and then get distracted again.

Geologists divide California into eleven geomorphic provinces, areas that share unique geologic histories, rock types and topography that are distinct from the surrounding areas. I generally refer to the province when I am describing a particular feature or place. I am categorizing the posts that exist thus far in the same way:

THE INTRODUCTION

The Other California: The Things it is Not: the first post describing what I am up to with this series: most people know about Yosemite, Sequoia, Death Valley and other famous places, but California has so much more...things and places that don't appear on the postcards

The Other California: Now This is a Postcard!: A brief overview of the geology of the state as it is represented on geologic maps and and introduction to the idea of provinces.

Come to California and You Could Die a Fiery Death! : A short introduction to volcanism in California

THE STATE SYMBOLS

Although the original idea came with a post about California's prairie lands, I pretty much first started out by describing the geologic significance of some of our state symbols.

The Other California: Already Off on a Tangent: A review of the familiar symbols, the Golden Poppy, the California Quail, the California Grizzly Bear, and our state mineral, Gold!

The Other California: Geology and our Other State Symbols: A look at the state mineral, the state rock, and the state gemstone, the one hardly anyone has heard of.

The Other California: Geology and our State Symbols Part 1: a discussion of the evolutionary history of our state fish, the Golden Trout

The Other California: Geology and the other State Symbols II: the incredible journey of our two state trees, the Sequoia and Coast Redwood

The Other California: Geology and the other State Symbols III: a look at our state fossil, the saber-tooth cat Smilodon Californicus.

The Other California: Geology and the other State Symbols IV: California has some unique Gold Rush-era towns, but nothing is quite like Bodie, off in the high desert east of the Sierra Nevada.

The Other California: Geology and the other State Symbols V : The strange politics that led to the establishment of the official California Silver-Rush Ghost Town.
Say Hello to California's New State Dinosaur, Augustynolophus morrisi: The first dinosaur discovered in California was found in our county, Stanislaus.

THE GREAT VALLEY

A huge 400 mile long valley filled with thousands of feet of sediments deposited over 160 million years, and one of the most fertile agricultural regions in the world

The Prairie Lands: California has its own version of savannahs, both present and past.

The Prairies of the Past: An exploration of the most important Pleistocene fossil quarry in central California, the Fairmead Landfill

The Prairie Lands and a Transforming Fault: A journey through Carrizo Plains National Monument and the best exposures of the San Andreas fault to be found anywhere

Back on the Prairielands: A springtime return to the prairies, now green and full of life

Mammoths and Sabertooths rise from the Prairies Again!: The Madera Fossil Discovery Center was almost complete and expected to open in June. Here is a preliminary look
Sharktooth Hill: That's about it...thousands and thousands of shark teeth and a great many other species. 

THE SIERRA NEVADA

The Sierra Nevada is the largest single mountain range in the United States, more than 400 miles long and averaging 50 miles wide. It also has the highest peak in the lower 48 states. Although composed mostly of granite, it also has large exposures of metamorphic and volcanic rocks that tell a remarkable story of traveling continents and terranes, as well as tales of violent eruptions.

A Gorge Deeper than the Grand Canyon: An exploration of little-known Pine Creek on the east side of the Sierra Nevada, and one of the most important mines in the country

The Other Yosemite at Hetch Hetchy: There was a counterpart to the Yosemite Valley, but we dammed it.

The Other Side of the Sierra, down the West Walker River: The West Walker River flows down the east side of the Sierra, and hosted the longest glaciers to be found on that side of the mountains.

An Enigmatic Gorge, the West Walker River Canyon: A strange entombed forest, and a deep gorge with a violent geologic temper.
The Day of the Fiddlenecks (A Trip Through the Mother Lode): A brief foray for wildflowers on Highway 132 in California's Mother Lode
There's an Endemic in those Red Hills! Life and evolution on one of California's unique environments, the serpentine soils. Exploring the Red Hills Area of Critical Environmental Concern
The California State Mineral Exhibit-This is art, darnit! One of the best ways to see the incredible mineral wealth of California is to explore the state mineral exhibit in Mariposa at the south end of the Mother Lode. Because of the morons in the state legislature, it is about to shutter its doors
It's a Real Grind...Chaw'se State Historical Park: A look at more grinding mortars than you'll ever see anywhere else, the Miwok culture, and some interesting metamorphic rocks
The Other California Goes Underground: Hella Hot Helictites at Black Chasm Cave: Never heard of helictites? That's because they are the first cave features to be destroyed. But we have a world class collection of them in the Sierra foothills
What do you do with a Used Forest?: The Sierra Nevada between Yosemite and Kings Canyon National Parks is terra incognita for most Sierra travelers. The region has been logged, mined, and grazed...and is still spectacular. We take an excursion on the Sierra Vista Scenic Byway
Why Worry About Yellowstone? We've got our own "supervolcanoes" in California. Some are active. Some have been extinct for tens of millions of years. At the Minarets we can explore one from the inside out

THE CASCADE RANGE

The Cascadia Subduction Zone is a place of geological violence: The crust underlying the Pacific Ocean is sinking beneath the western edge of the North American Continent, producing earthquakes, mountain-building, and volcanism. Two of California's most familiar volcanoes formed here, and the largest volcano in the state sits astride the boundary with the Modoc Plateau

Exploring California's Biggest Volcano: An introduction to the Medicine Lake Highland, one of California's most active volcanoes.

Geologists Who Live on Glass Mountains Shouldn't....: Looking at volcanic glass, obsidian and pumice, on the Medicine Lake Highland, with a view towards the Modoc Plateau, too.

A Land of Fire and Ice (but mostly ice): California's largest glaciers

Five For the Price of One: California's most prominent volcano is really five volcanoes, with a violent past.

A Monday Mystery: A river that comes out of nowhere, and a gratuitous picture of a deer family

A Mystery Solved, and One of California's Prettiest Little Waterfalls: McArthur Burney Falls is California's second oldest park, and is one unusual waterfall.

Lassen Peak, A Volcanic Afterthought: A well-known volcano that sits on the remains of a much older, much larger volcano, Mt. Tehama

Getting all excited about natural disasters: an eyewitness account of some of the events surrounding the 1914-15 eruption of Lassen Peak.

THE MODOC PLATEAU

The Modoc Plateau is a high flat region underlain by thick flows of basalt lavas in the remote northeast corner of the state. It is one of the least-known areas of California, but has some nice geological surprises.

California's Biggest Volcano: here is the first surprise; the biggest volcano is not named Shasta or Lassen!

Waiter, There's A'a in My Pahoehoe!: A comparison of basalt lava flows at Lava Beds National Monument

The Volcano Underground: the formation of lava tubes (via a short excursion in Hawaii) and Lava Beds National Monument

Exploring the Volcano Underground: Walking and crawling through the most extensive lava tube system in the continental United States

Whispers From the Past: Huge explosions from 270,000 years ago, and the largest petroglyph panel in the United States

Cries From the Past: A tale of rebellion, resilience and betrayal; the Modoc Indian War of 1872-73. And why armies should study geology before fighting wars.

THE KLAMATH MOUNTAINS

In northwest California, a series of mountain ridges reveal stories of continental and oceanic fragments that were crushed into the western edge of North America. The rocks bear a close resemblence to the Sierra Nevada, although they are offset more than sixty miles.

Flotsam and Jetsam: An introduction to the Klamath Mountains as a series of accreted terranes, tracts of crust and old ocean floor that traveled hundreds or thousands of miles.

Havin' fun with Sasquatch: a discussion of the legendary and mythological creature that supposedly dwells in the Klamaths
I've seen these mountains before! The Big Ripoff: Viewed on a geologic map, the Klamath Mountains look like a continuation of the Sierra Nevada, but lie sixty miles farther west.

A Journey to the Center of the Earth (sort of): A review of the some of the rocks from the deep crust and mantle that are found in the terranes of the Klamath Mountains

Taking Stock of Castle Crags: One of the most imposing sights (besides Shasta) to be seen on a journey north on Interstate 5, the Castle Crags are towers and domes of granite, surrounded by more easily eroded metamorphic rocks

THE COAST RANGES

The series of mountain ranges that roughly parallel California's coastline are one of most diverse areas of the state from a geologic standpoint. There are thick sequences of sedimentary rocks including the Great Valley Group and elements of the Franciscan Complex, and there are plutonic and metamorphic rocks of the Salinian Block (and parts of the Franciscan). There are even volcanic rocks and potentially active volcanoes.

I Need This Like I Need a Hole in the Head: Scenic Bodega Head at Bodega Bay was the nearly the site of one of the most mind-bogglingly stupid energy developments ever conceived by the minds of engineers
Baymouth Bars - It's Five O'Clock Somewhere? Along the incredibly rugged north coast amid the violent surf there are long, perfectly straight sand bars that seem to defy explanation. They're explained here Humboldt Lagoons State Park
A Mystery Photo For a Saturday: A look at San Francisco from a unique angle, Monte del Diablo
The Thicket of the Devil (the mystery photo revealed): An introduction to a place with an incredible view, Mt. Diablo. How it got its name and why every landowner in Central California should care
Limekiln State Park Part 1, Part 2, and Part 3: Limekiln is a beautiful gem of a state park on the Big Sur Coastline. Unfortunately we have morons in the state legislature and this park is closing. See what is being taken from us (PS: It was eventually saved)

Catch it While You Can- The Devil's Slide: You can no longer drive over one of the most notorious rockslides on Highway One. But you can walk it! 

BASIN AND RANGE

The crust of the earth east of the Sierra Nevada and Peninsular Ranges is being torn apart by horizontal extensional forces that have produced an alien landscape of deep fault valleys (grabens) and high mountain fault blocks (horsts)

The West Walker River and the Antelope Valley: A deep fault valley becomes an important ranching and farming region

Dammed if we do Dam, Dammed if we don't Dam: An unusual reservoir without a dam, Topaz Lake stores Walker River water, but has great fishing too. Why is it there?

Damned if we do Dam, Damned if we don't Dam: A slightly modified name, and a much bigger issue - What are we going to do about Walker Lake? It's dying. It's also in Nevada, but it is a California river.

MOJAVE DESERT

Often ignored or tolerated by tourists on their way to Las Vegas, the Mojave Desert is one of the most geologically diverse regions of California

The Calico Mountains: An exploration of a unique mountain range, well beyond the confines of the tourist trap ghost town.

Prairies past and Some Great Folds: A closer look at a parking lot in a tourist trap

A Wandering Volcano and a Floral Outburst: The Antelope Valley has a springtime show of wildflowers that is simply audacious, and the underlying rocks include half of a volcano. The other half is nearly 200 miles away...

Caught in the Vise (the Western Mojave Desert): A discussion of complex fault relationships in the western Mojave and another chance to show some wildflower shots.

COLORADO DESERT

THE TRANSVERSE RANGES

A diverse series of mountain ranges that run against the grain, trending east-west instead of north-south. These include some of the highest mountains in southern California

The Other California: A Friday Fun Foto: A first glance at San Gorgonio Peak, the highest mountain in southern California, and the southwesternmost glaciated peak in the United States

Scarps to the Left of Me, Sag Ponds to the right, Here I am, Stuck in the Middle with You!: The San Andreas fault cuts across many of California's province. In this post we look at some fault features at the top of the Grapevine in the Transverse Ranges
A Monday Mystery Photo: A quick introduction to the Cajon Pass country where the San Andreas fault splits the San Gabriel Mountains from the San Bernardino Mountains
Cajon Pass and No Strange Sci-Fi Creatures: Cajon Pass, the major freeway access route into the Los Angeles basin, is filled with strange looking sedimentary rocks tilted this way and that. But it's not where Captain Kirk fought the Gorn...
The Mountains of My Youth: The eastern San Gabriel Mountains aren't all that familiar to people from outside the state, but they are spectacular and they were the mountains where I grew up. We explore an extraordinary gorge, San Antonio Canyon
Hemming and Hawing on the Hogback: The San Gabriel Mountains are the steepest mountains in the world. Often the only flat spots are on dangerous stream floodplains and on top of landslides. Several examples from San Antonio Canyon include the Hogback and Cow Canyon Saddle
A Canyon as Deep as the Grand, and a Road For No Reason: The Glendora Ridge Road offers some of the greatest panoramas of any road in southern California, and there doesn't seem to be a reason for it being there. I suspect I know what the reason is
The Forbidden Valley: An introduction to the San Dimas Experimental Forest
A Minor Challenge: A quiz to introduce the unusual geology of the Santa Clarita Valley
Dreams of Avarice and the First Gold Rush: You thought the gold rush started in the Sierra Mother Lode? There was a rush six years earlier, but the Mexican miners kept their secrets better (and there wasn't very much gold, either)
The Oldest Rocks (Well, maybe...): The San Gabriel Mountains have very old rocks, maybe the oldest in the state. But it depends on how you define "oldest". A short introduction to radiometric (isotopic) age dating

A Bit of the Rarest Ecosystem in SoCal at the North Etiwanda Preserve This is what happens when the schist hits the fan. Literally, there is schist, and there is a fan. Also, learn about the Riversidian Alluvial Fan Sage Scrub (RAFSS) ecosystem...
It's Not The The Tar Tar Pits, and Saving the Coast a Bit at a Time: The story of the Carpinteria Bluffs Nature Preserve and the "other" tar pits.

PENINSULAR RANGES

A granitic mountain block vaguely similar to the Sierra Nevada, but also very different. The "peninsula" refers to Baja California, which makes up the bulk of the province

The Other California: Another Friday Fun Foto: A brief introduction to San Jacinto Peak, the highest mountain in the Peninsular Ranges, and one of the most prominent mountains in the state, with a 10,000 foot slope in one area.
A Mystery Photo for the Day: A view of a rock that looks like it belongs somewhere in the Sierra Nevada, but that is not where it is...
When is a Peninsular Range Not a Peninsula? Baja California is a peninsula, but the rocks continue into Alta California. This post explores the village of Idylwild next to the highest part of the province at San Jacinto Peak.

The Deepest Pass in North America, and Finally Taking THE Tramway: Well, sure, the Palm Springs Aerial Tramway is on a lot of postcards, but how many of them tell you the geological story?

I clearly have lots of ground to cover, and will update this page as necessary.

Recalling California's Second Worst Disaster Ever: The Victims May Finally Get a Voice

A number of people have brought to my attention this article in the Press Enterprise about efforts to construct a memorial to the victims of the St. Francis Dam disaster. Such a memorial is long overdue. I tell this story at the beginning of every one of my classes, and in thirty years, not one student had ever heard of it. I'm reposting my January 2012 blog on this disaster below. Thanks to Representative Steve Knight and Senator Kamala Harris for sponsoring the bill that establishes the memorial, and Dianne Erskine-Hellrigel, the local community organizer who is leading the efforts to raise funds for the memorial. If you wish to donate, contact the St. Francis Dam National Memorial Foundation, c/o Dianne Erskine-Hellrigel, 24820 Fourl Road, Newhall, CA.

Hindsight is harsh.

Sometimes choices and judgements are made to save time, to save money. Sometimes choices are made in unfortunate ignorance, in a time when no one could have foreseen or recognized the right choices to be made. Sometimes there is no one there to provide perspective, to provide alternatives. And then people die. Lots of people.

Ask folks what they think was the worst disaster in California history and many will get it right. Upwards of 3,000 people died in the 1906 earthquake in San Francisco, and the event has shaped the psyche and attitude of many people in the state more than a century afterward. And it was brought about by a natural event.

The second worst disaster in the history of the state is far less known. Some might guess another earthquake, like the Long Beach quake of 1933 (115 dead) or the Loma Prieta earthquake of 1989 (63 dead). Historians might point to the Port Chicago munitions explosion of 1944 (320 dead). Few people are aware that it was the collapse of a dam, and that the collapse was the result of many poor choices. Hindsight is a harsh judge, but many of the mistakes were "before their time" so to speak. The fact that it happened maybe has prevented worse disasters in the intervening years.

Time (and a great deal of government effort) has erased much of the record of our state's second worst disaster. As far as I could see there is not a single plaque or monument, either concerning the horrific event, or commemorating those who were lost. There is a small cemetery where some of the victims were buried.

Looking at the slide area on the left side of the picture above, it is hard to believe that a 200 foot high dam was anchored there, in the incompetent mica schist. It is hard to believe that the failed slopes in the picture obscure an even deeper and bigger megaslide.

It is hard to look at the flat ridge on the right side of the picture above and realize that no one ever thought to check the effect of soaking the seemingly solid conglomerate in water. It is glued together primarily with gypsum, a mineral that dissolves in water. The rock falls apart when saturated.

Maybe the most stunning realization is that the schist and the conglomerate are separated by a fault zone. An inactive fault by all appearances, but a fault nonetheless. They built the dam on a mega-landslide, and on a fault zone.

It is difficult to envision that on the night of March 12, 1928, the recently completed dam failed so catastrophically that the floodplain in the photos above and below was inundated with 140 feet of water flowing at a rate of 1.7 million cubic feet per second (California's biggest river, the Sacramento, averages 30,000 cfs, and the record flood on the river was 650,000 cfs).

What happened?

As Ron and Randy correctly surmised, Friday's mystery photo was about the destruction of the St. Francis Dam in 1928. I consider it one of the most important geological events ever to happen in the state, not because a great many people died, but because they died as a result of a disregard or lack of knowledge concerning human construction projects and the geological foundations on which they are built. Earthquakes and volcanic eruptions are inevitable geologic events, but the events of 1928 were completely avoidable.

In the early twentieth century, Los Angeles was at a crossroads. The city was growing fast, and the water needs of the metropolis far exceeded locally available supplies (according to city officials anyway). The story of how the city stole (legally stole, but stolen nonetheless) the water from underneath the people of the Owens Valley is a legend of California history. The fact that much of the water went to irrigation in the San Fernando Valley instead of the city just added to the scandal. Having completed the Owens Valley Aqueduct, one of the largest public waterworks ever conceived, the city needed someplace to store the water locally, especially in preparation for drought conditions. William Mulholland, the superintendent of the predecessor to the Los Angeles Department of Water and Power, oversaw the design and construction of a series of reservoirs around the Los Angeles Basin. Nine were constructed, and St. Francis Dam in San Francisquito Canyon above the Santa Clarita Valley was the largest, with a storage capacity of 38,000 acre feet. The dam itself was about 200 feet high, and just over 600 feet across. It was a concrete gravity-arch dam, one that depended on the nature of the rock in the abutments to maintain stability.

Construction was begun in 1924 and complete in 1926. During the construction Mulholland directed that the dam be made 20 feet higher than in the original plans, but he made no alterations at the base to compensate for the additional weight of the water. The filling of the dam took another two years, and was complete on March 7, 1928. On the morning of March 12, the dam keeper noted a leak of muddy water and alerted Mulholland. Small leaks of clear water from dams are usually expected; muddy leaks from a dam are very bad.  Mulholland declared that the mud was from some recent road construction and that the dam was safe. 12 hours later, the dam keeper was dead, the first victim of the collapse of the St. Francis Dam. In the hours that followed at least 600 more lives were lost.

To his credit, Mulholland took the blame for the disaster. Although he was never convicted of any crime in the matter, his career was over. He died seven years later.

Accounts at the time suggested that failure occurred as water channeled through the conglomerate along the fault contact. A reassessment of the failure by J. David Rogers finds multiple causes for the disaster, with the reactivation of the ancient landslide being the most important factor, along with hydraulic lifting of the dam which was caused by water pressing against the topmost part of the dam (which had been made higher without compensating at the base). Rogers lists many other deficiencies, including the weakness of the rocks in the dam abutments (I refer interested readers to this very fascinating pdf by Rogers that provides a blow-by-blow analysis of failure of the dam and a great deal of background information on the disaster).

Incredibly, despite the total evisceration of the dam, the central part remained standing, a 200 foot high monument to the destruction. After a sightseer fell off the top (his "friends" had tossed a rattlesnake at him), the city quarried holes in the base, filled them with five tons of dynamite, and blew up the remaining tower. Other blocks were also destroyed, as if they were trying to erase all memory of the event. One of the blocks was the "outcrop" I used in the Friday mystery photo.

The U.S. Geological Survey has a (much appreciated) photo archive from which I have gathered these photographs of the aftermath. In the photograph below, the fault line dividing the Vasquez Conglomerate from the Pelona Schist can be clearly seen (the lighter Pelona in the foreground, the dark Vasquez on upper ridge). The fault is inactive, and no earthquakes are implicated in the failure, but had the dam not failed, rising water pressure along the fault could conceivably have eventually caused renewed quake activity. The phenomenon has been noted elsewhere.

Blocks of concrete weighing thousands of tons were carried in the floodwaters nearly a half mile downstream. The magnitude of the disaster is hard to comprehend. Normal rivers have trouble moving boulders only a foot across. Besides the sheer magnitude of the flow, debris from the landslide buoyed up the blocks.

The block below was a half mile downstream. It measured approximately 63 feet long, 30 feet high, and 54 feet wide.

It is hard to find much that is positive in this disaster, but changes were made in the aftermath. The input of qualified engineering geologists became a requirement in dam-building, and much more attention was paid to the geological setting of reservoir sites. Boulder Dam on the Colorado River, one of the largest dams in existence is not in Boulder Canyon. Following the St. Francis disaster, the site of the dam was changed to Black Canyon when it was decided that the rocks that would anchor the dam were more stable there.

It would not be at all correct to say that we learned every possible lesson in dam construction. The 1963 tragedy at Vaiont Reservoir in Italy and the 1975 collapse of the Teton Reservoir, Idaho are vivid examples of unlearned lessons.

Hindsight is harsh. But it can be a teacher, too.

The California That Once Was: The San Luis National Wildlife Refuge

Great Blue Heron at the entrance to the San Luis NWR

I live in an extraordinary place, a place that does not always receive the respect that it deserves. In much the same way that travelers refer to the Midwest as "fly-over states", my home is the "drive-through valley".  The Great Valley (called by some the Central Valley) is a 400 mile long and 50 mile wide province that must be traversed by Southern Californians who want to reach the Pacific Northwest, or coastal Californians who want to reach Yosemite National Park or the Sierra Nevada ski resorts.

San Luis National Wildlife Refuge from above. It lies on the floodplain of the San Joaquin River.

Many people find the journey an arduous exercise in white-line fever, an endless flat region covered by millions of acres of orchards and fields of crops, or cattle stockyards, or used car lots on the edges of poor-looking towns. I'm willing to grant that it is often not a pretty sight. There is a reason that our cities often wind up last on the lists of "best places to live". Our skies are often the most polluted in the United States.

In the thirty years that I've lived here, I've come to discover a different Great Valley. It's the five percent of the valley that still retains the character of the land that existed before it was co-opted by agricultural development. It's a recurrent theme of my blogging adventures because each of these adventures expands my world just a little bit.

Today's journey was the auto-tour through the San Luis National Wildlife Refuge. The refuges range the length of the valley, providing winter sanctuary for migrating birds, but also providing a last stand for many native species of the valley from the smallest of bugs to the rodents and larger grazing animals to the largest remaining predators, the eagles, the hawks, the coyotes and foxes, and sometimes even mountain lions. The gigantic herds of Tule Elk and Bison have been gone for more than a century, although the elk are protected as a species in some of the refuges, including 60 of them at San Luis. Without the millions of grazing animals, the refuge managers allow limited grazing of the prairie by sheep and cattle to maintain the integrity of the grasslands. I imagined the scene above as a wolf patrolling the margins of a giant herd grazing elk, looking for a weak or sick individual to take down. The reality was the opposite, of course. The dog was watching over the sheep.

I don't see them often, but Mule Deer do inhabit the grasslands. We saw nearly a dozen of them today. I've mostly given up on trying to take decent pictures, but I really liked this one.

Red-tailed Hawk at the San Luis NWR

The stars of the refuge are the myriads of bird species that call them home. Some of them only stay for a few days or a few months as part of a long migration, while others stay year-round. Each refuge includes a wide range of habitats, including freshwater marshes, riparian areas (river channels), prairie grasslands, and alkali salt flats. The auto-tours at the refuge sample most of these environments, and several hiking trails are available as well.

In the first five miles of the tour we didn't see a great many migrant species, so I thought the Cinnamon Teal (above) and the Great Blue Heron (opening photo) that greeted us at the entrance to the refuge were going to be the avian stars of the day. But then we made the turn towards the Souza Marsh at the southeastern edge of the refuge. And everything changed in a moment. We had found the migrants.

There were hundreds of Snow Geese, Greater White-fronted Geese, Northern Shovelers, Cinnamon Teals, Northern Pintails, Mallards, American Coots, Pied-billed Grebes, and to our great delight, several dozen Tundra Swans (I count five of the species in this picture alone). The swans aren't rare, but Mrs. Geotripper and I have only found them once before on our travels. They dwarf the other birds in the marsh.

Last year was a good year for rain, and water was plentiful after five years of drought. Most of the marshlands were flooded, providing better than normal habitat for the birds. Unfortunately, the new year is proving much drier, with a near record low snowpack in the mountains upstream, and dry conditions in the long-range forecasts. Uncertainty lies ahead.

The prairies and river environments have always existed in a cycle of drought and flood. The biggest variable in the present day and in the future is the effect of global warming on the environment here. The predictions are for more drought, although some climate models suggest more rain in some years. Unfortunately that means less snow, and more variable river flows, heavier in the spring, and far less in the summer and fall. It's hard to predict the coming changes in the ecosystem that will follow. That ecosystem of course includes the species Homo sapiens, who despite their arrogance about "ruling over nature" and all that, are just as vulnerable to climate change as the rest of the species who live here. Their one advantage is the ability to recognize the situation they are in, to provide reasonably accurate predictions about the future, and the ability to affect the outcome.