Driving Through the Most Dangerous Plate Boundary in the World: In the Pleistocene, a Different Kind of Danger

An Egret and Tule Elk at the San Luis National Wildlife Refuge near Los Banos

The Great Valley began as a shallow sea (a forearc basin) between the Mesozoic subduction zone and the Ancestral Sierra Nevada volcanic arc. As noted in the previous post, the sea filled with thousands of feet of sediments, and as the subduction zone transitioned to a transform boundary, the sea gave way to land, and the one of the most fertile valleys in existence emerged. The Great Valley has become one of the most important agricultural regions on the planet. 95% of the original landscape has been altered to grow food and feed. If the land isn't covered by crops, it's covered by pavement and cities.

The Cosumnes River Preserve north of Stockton

As I said in the previous post, the agricultural development isn't necessarily a bad thing. With an increasing population of mouths to feed in the world, it would be silly not to utilize the richest soils on the planet. But we do live in a highly interconnected ecosystem, and we need to preserve what we can of the richness and diversity of life in our world. A few wetlands have been protected from development to allow the survival of some of the migratory birds that overwinter in our valley, like the Sandhill Crane, the Ross's Goose, the Snow Goose, and many others. Some of the rivers flowing through the valley are still allowed to reach the sea, preserving salmon and other aquatic species. There is a great deal of conflict about where to define the limits of water and land use, especially in this horrific drought year.

The Cosumnes River north of Stockton

This past year I spent as a new birder has been a revelation as I have sought out those small corners and edges of the valley that preserve something of the original ecological richness. I was stunned to find that flocks of tens of thousands of cranes and geese spend their winters just a few miles from my home near Modesto.

Snow Geese and Ross's Geese at the Merced National Wildlife Refuge

Tule Elk, among the largest members of the deer family (aside from the Moose), used to live in the valley by the millions as well. One subspecies was down to a single breeding pair in the late 1800s, but they were protected by a rancher, and several thousand now survive in some widely separated refuges. The wolf was driven to extinction, as was the terrifying California Grizzly Bear. Other species retreated into the Coast Ranges and Sierra Nevada foothills.

The Tule Elk herd at the San Luis National Wildlife Refuge

This blog series has mostly been about the "most dangerous plate boundary" in the world, referring to the geologic hazards inherent in living near an active subduction zone: earthquakes, tsunamis, and volcanic eruptions. But a different kind of danger lurked in the Great Valley when humans first arrived: the so-called "megafauna": an ecosystem of large mammals that mostly went extinct just 10,000 or so years ago.

Wooly Mammoth at the Paige Museum

One of the most imposing creatures would have been the mammoths. These elephant relatives were widespread across Asia, Europe and North America, and passed into oblivion only a few thousand years ago. They were gone from the continents by 10,000 years ago, but a small population (both in stature and in numbers) survived on Wrangell Island in eastern Russia until 4,300 years ago.

There were giant ground sloths (above), and camels. Lots of camels, so much so that they are one of the two most common animals found in the Fairmead paleontological site near the Great Valley town of Madera. The Fairmead excavations have been the most important source of fossil material on the valley floor (the fossil species are also well known from the La Brea Tar Pits in Los Angeles.

The other common fossil is the horse. Most people think horses came to America with the Spaniards in the 1500s, but they actually evolved in North America and spread to other parts of the world before going extinct in their ancestral home around 10,000 years ago. There were also species of deer and pronghorn, and the buffalo roamed the valley as well.

Though any of these creatures could have injured humans in self-defense, it was their predators that would have made life in the valley terrifying. There were huge Sabertooth Cats. There were Jaguars and American Lions (pretty much the same as African Lions).

The California Grizzly Bear was dangerous enough, but even larger bears lived in the valley as well. The Short-faced Bear was a good 50% larger than a Grizzly, and may have been the largest terrestrial mammal predator ever. They were five feet high at the shoulder, and stood 11-12 feet tall if they chose to. Terrifying indeed.

They were smaller than the cats or bears, but the Dire Wolves hunted in packs, and that made them perhaps even more dangerous than the others. They were 25% larger than today's wolves.

The Great Valley would have been a dangerous place for humans when they arrived 13,000 years ago or earlier. It's possible that the megafauna is extinct today because humans had tools for hunting and defense, but the connection is not yet clear. Climate change could have played a role too, or disease, or any other number of possible explanations. In any case, I feel a sense of loss when I wander through the few remaining pieces of original habitat imagining the creatures that used to live here. A sense of loss, but at least I am not so fearful of being maimed or killed.

Are you interested in seeing more of these creatures? If you are ever traveling in the Great Valley for any reason, make the time to stop at the Fossil Discovery Center in the Madera area. The very famous La Brea Tar Pits are the other great source of information on the extinct megafauna. The Paige Museum at the tar pits is an excellent place to visit when you are in Los Angeles.

You Think Your Halloween Monsters are Scary? Imagine What Your Ancestors Thought About These Terrifyingly Real Beasts...

(Modified from my post of June 8, 2011)

Happy or scary All Saint's Eve or Halloween, whatever your pleasure might be. As you cheer on the zombies and alien predators extorting candy from you, give a few thoughts about what would have been really scary: the terrifying animals that humans lived with many centuries ago.

Have you ever wondered why shadows are so effective in the best horror movies? It's pretty clear to me that there is a collective genetic memory in all of us of the monsters that we think of as myths today, but which were horribly real as recently as 12,000-13,000 years ago. The world was full of creatures that wouldn't have minded dining on us, and deep in our collective consciousness is a reflexive response to particular shapes and shadows. The pareidolia I wrote of once was a survival mechanism; we needed to see those faces in the underbrush in time to climb or flee to safety.

So who belonged to that mysterious shadow above? It was a short-faced bear, Arctodus simus, that lived in my home region, the Central Valley of California. Grizzly bears were a common presence in California when the Europeans arrived two hundred years ago. They described many of the native Californians as bearing wounds of encounters with the grizzlies, and compared to spears or arrows their guns were not much better as a defense against them. The short-faced bear was bigger, maybe 2,000 lbs or more. It may have been the largest mammalian predator ever.

There were roving packs of Dire Wolves, Canis dirus, as large or larger than their cousins in Canada or Alaska...

...and there were the Saber-tooth Cats, Smilodon fatalis, (below) along with the American Cheetah (Myracinonyx sp.)  and the Scimitar Cat (Homotherium serum). We have been living with the comforting insulation of modern civilization for a long time, but even a glance at a skeleton of these long extinct creatures can awaken nightmares in the recesses of our brains.

This museum display in Sydney gave me the willies...

If you want to see the rest of these creatures in a slightly less threatening atmosphere, check out the Fossil Discovery Center of Madera County, which opened for business a few years ago. The fossil creatures on display were found by the bulldozers of the Fairmead Waste Facility. They were digging a garbage dump, and found a treasure trove of fossil bones; 27 species of mammals and a half dozen other creatures dating from the Pleistocene. I find it to be a wonderful science resource for the region. It is well worth a visit.

Fossil Discovery Center of Madera County

19450 Avenue 21 ½
Chowchilla, CA 93610

Take the Hwy 99 Exit 164, SW corner of Road 19 ½ & Avenue 21 ½

Our Human Nightmares...Shadows of our Collective Past

Have you ever wondered why shadows are so effective in the best horror movies? It's pretty clear to me that there is a collective genetic memory in all of us of the monsters that we think of as myths today, but which were terrifyingly real as recently as 12,000-13,000 years ago. The world was full of creatures that wouldn't have minded dining on us, and deep in our collective consciousness is a reflexive response to particular shapes and shadows. The pareidolia I wrote of in a recent post was a survival mechanism; we needed to see those faces in the underbrush in time to climb or flee to safety.

So who belonged to that mysterious shadow above? It was a short-faced bear, Arctodus simus, that lived in my home region, the Central Valley of California. Grizzly bears were a common presence in California when the Europeans arrived two hundred years ago. They described many of the native Californians as bearing wounds of encounters with the grizzlies, and compared to spears or arrows their guns were not much better as a defense against them. The short-faced bear was bigger, maybe 1,000 lbs or more...

There were roving packs of Dire Wolves, Canis dirus, as large or larger than their cousins in Canada or Alaska...

...and there were the Saber-tooth Cats, Smilodon fatalis, (below) along with the American Cheetah (Myracinonyx sp.)  and the Scimitar Cat (Homotherium serum). We have been living with the comforting insulation of modern civilization for a long time, but even a glance at a skeleton of these long extinct creatures can awaken nightmares in the recesses of our brains.

This museum display in Sydney gave me the willies...

But if you want to see the rest of these creatures in a slightly less threatening atmosphere, check out the Fossil Discovery Center of Madera County, which opened for business last year. The fossil creatures on display were found by the bulldozers of the Fairmead Waste Facility. They were digging a garbage dump, and found a treasure trove of fossil bones; 27 species of mammals and a half dozen other creatures dating from the Pleistocene. I finally got to see it a few weeks ago, and I find it to be a wonderful science resource for the region. It is well worth a visit.

Fossil Discovery Center of Madera County

19450 Avenue 21 ½
Chowchilla, CA 93610

Take the Hwy 99 Exit 164, SW corner of Road 19 ½ & Avenue 21 ½

The Other California: Mammoths and Sabertooths rise from the Prairies again!

Painting for the San Joaquin Valley Paleontology Foundation by David Douglas

Sometime back, I talked about the rich paleontological discoveries being made at the Madera County Landfill at Fairmead near the center of California's Great Valley. I mentioned the efforts to build a visitor facility, the Fossil Discovery Center, but also mentioned that I had not had the opportunity to visit the site yet. That changed today, and I am happy to report that the facility is rapidly becoming a reality. It is expected to be open for business in June.

The Fossil Discovery Center is on the corner of Road 21 1/2 and Road 19 a short distance from Highway 99, near the town of Fairmead. As can be seen, the exterior of the building is essentially complete, and when I stopped by, workers were busy putting in the high-tech connections, and working on the interior labs and classroom. I was pleased to have the opportunity to talk to Grady Billington, the President of the Board of the Directors of the San Joaquin Valley Paleontology Foundation. He kindly provided me a tour of the facility and discussed their plans for introducing valley residents to the fascinating prehistory of the region.

A full-sized mammoth skull has been hung in the central atrium. More than three dozen species of animals have been discovered at the landfill, including mammoths, mastodons, sloths, camels, horses, dire wolves, smilodon sabertooths, and short-faced bears. Skeletons of most of these animals will be part of the display when it is complete.

The original environment where the animals lived and died was a prairie with ponds and rivers flowing out of the adjacent Sierra Nevada. An outdoor pond has been constructed to recreate some of the conditions present when the Pleistocene animals were roaming the area. The hill in the background of the photo is the landfill site where the fossils were uncovered.

For more information, check out the website for the San Joaquin Valley Paleontology Foundation, or look for almost daily updates on the Fossil Discovery Center of Madera County site on Facebook.

For those who are new to Geotripper, the "Other California" is my long-running web series on the fascinating geological places in my fine state that don't usually show up on the postcards. Thanks for reading!

Time Beyond Imagining - A Final Struggle for Life on the Colorado Plateau

...the massive creature wandered slowly through the dry grasslands. It had been a long hot year, something that had been all too common during the decades the animal had been alive. Foraging was difficult, and the creature was near the point of starving. The large elephant-like animal felt vaguely lonely; it was a herd creature, but it had actually been years since he had seen another of his own kind. He was aware of the pack of predators that had been following him for several days now. They too had the look of hunger, too thin, gaunt, with intense yellow eyes following every movement of the mammoth, but not quite desperate enough to try attacking such a huge beast. They could see it was weak, and they hoped for an opening.

The elephant could smell water. There was stream nearby, maybe a promise of green grass. The trickle of water lay at the base of a dangerously steep slope, but the mammoth was becoming desperate. He carefully stepped over the ledge and started down the rocky slope towards the water. Disaster! Somehow a rock slipped, and the animal lost his footing and tumbled down the slope. There was a crunching sound, and a horrific pain shot through the creature's leg. Something was terribly wrong now, and despite his struggling, he could not stand. The wolves heard the commotion. What was a tragedy for the mammoth was the temporary salvation for the giant wolves. They moved in, and in the moments that followed, the very last individual of the elephant clan on the Colorado Plateau passed into oblivion. Though they ate their fill that day, the wolves were doomed too. In these final centuries and decades of changing climate, they would find fewer and fewer of the large creatures they had evolved to consume, and they too soon passed into oblivion...

The story I've just told is entirely fanciful, with no direct basis in reality. I'm not describing some paleontological excavation, because we don't have one that is known to be the final individual of a species. But the fact is, numerous species became extinct during the last 10,000 years, and there was a final living individual mammoth. There was a final pack of dire wolves, though not at the same precise time. My little story could just as easily have included human beings who stood over the dying mammoth instead of wolves. Anthropologists argue the point.

The last few thousand years of geologic events of the Colorado Plateau are really mostly biological in nature. And to me they represent one of the saddest episodes in the entire two billion history of life in the region. In the last two million years before the present, the canyons and mountains, mesas and buttes of the Plateau looked much as they do today with one major exception. An ice age gripped the world, with a dozen or more cold periods when ice advanced across the northern tier of the North American continent. Though the ice never reached the plateau country, the climate was cooler and wetter, and forests covered what are now sagebrush flats, and sagebrush covered what are now barren desert expanses.

In this environment of rich vegetation growth, a complex ecosystem evolved, with numerous large species of plant foraging mammals, the megafauna of North America. The species that lived on the plateau included mammoths (2nd photo), mastodons (1st photo), camels, giant sloths, bisons, horses, musk ox, bighorn sheep, and mountain goats. They were preyed upon by giant American lions (4th photo), saber-tooth cats, dire wolves (3rd photo), and occasionally by short-faced bears. The lions were bigger than their African cousins, the wolves and bears bigger than their living relatives by a factor of 50%. They had evolved to take down large prey.

These species lived across the continent, and the pictures above are actually specimens from southern California. They are examples of some of the incredible discoveries from the La Brea Tar Pits, where animals were trapped by the hundreds in the black goo. The animals thrived across the land for several million years, but around 10,000 years ago nearly all of them went extinct. Their disappearance coincided with two events: the end of the latest ice age, and the arrival of humans on the North American continent. Which brought about their end? Was it a combination of factors? We don't really know yet. There have even been some suggestions by researchers that an asteroid impact affected the North American megafauna.

In any case, I feel a sense of loss that these animals are gone. Part of the adventure of visiting a national park like Yellowstone is to see the bare remnants of this megafauna: the moose, elk, buffalo and grizzly bears. What an adventure it would have been to see mammoths and other giants wandering the mesas and buttes of the Colorado Plateau!

We've nearly reached the end. I have been exploring the geology of the Colorado Plateau for well over a year now, and one final major event in the geological story remains to be explored. Next time!