Geotripper Missing in Action? Nah, Just on the Road.

If you've noticed a distinct lack of blog updates lately, it's not been for lack of creative ideas. I've actually been in the wild hinterlands of the eastern California desert, specifically Death Valley. We had a marvelous time, but we also experienced a bit of the harshness of the "Broken Land" as Frank DeCourten calls it. There's a bit more cellular and Wi-Fi access in recent years for better or worse, (better for emergency situations), but no time when dealing with a group of students (who were great). Besides, a desert night is meant to be experienced, not ignored in favor of a computer screen. The stars were beyond belief.

In any case, the stories will unfold in the next few blogs. There were some incredible sights, and I look forward to sharing them. Today's picture was a camp visitor on our first night of the trip on the Kern River near Bakersfield.

Another Moderate Earthquake in Central California: 4.9 Magnitude...in the Great Valley???

The Wasco 4.9 earthquake, as recorded at Modesto Junior College

California has been shaken by another near-magnitude 5 earthquake, and this one is a bit odd. It hit in the Great Valley, one of the few places in California NOT known for having faults and earthquakes. It occurred near the south valley town of Wasco, and had a magnitude of 4.9, along with a couple of aftershocks as high as magnitude 2.6. The first motion solution suggests right lateral strike-slip motion in the same orientation as the San Andreas fault, which lies to the west in Coast Ranges.

Not the kind of place one expects to see fault zones...

The Great Valley indeed has few active faults, but the Bakersfield region is a definite exception. The south end of the valley is a structural nexus in California where five geologic provinces come together. The region is riddled with structures related to movement along faults like the San Andreas, the Garlock, and the White Wolf, which generated a magnitude 7.6 magnitude earthquake in 1952 that killed a dozen people. A few faults are mapped close to Wasco, including the Pond-Poso Creek fault (see the California State interactive fault map at http://maps.conservation.ca.gov/cgs/fam/).

Source: http://earthquake.usgs.gov/earthquakes/eventpage/ci37528064#impact_shakemap

I have to admit that my first thought upon seeing quake reports was that it resulted from waste disposal related to fracking . The more I've looked though, the less I am concerned about this possible cause. The quake was deep, around ten miles, and has motions consistent with a tectonic origin. There are no reports of damage that I have seen.

The U.S. Geological Survey event page for the earthquake can be seen at http://earthquake.usgs.gov/earthquakes/eventpage/ci37528064#general_region.

Treasures From the Earth in the Great Valley: What the heck was living here?

Standing on a barren hillside east of Bakersfield, one looks over a dry landscape peppered here and there with oil drilling rigs. Because of the recent rains, the grass is green, but roasted brown is normal for these badlands. It's hard, standing in this desert, to visualize that this was once a shallow sea, a sea that was filled with life. 15-16 million years ago, there were ancient species of clams, snails, fish, rays, sharks, dolphins, seals, sea lions, and whales. The nearby coastal plains were populated with horses, camels, primitive species of elephant, and predators who were the ancestors to today's large felines and canines.

The Great Valley began existence as a forearc basin between the volcanic range of the Ancestral Sierra Nevada, and the vast Cascadia trench and subduction zone that formed the western boundary of North America for much of the last two hundred million years. The shallow sea collected sediments from the rising mountains, and the basin floor subsided beneath the weight of the strata. Ultimately, the sediments in the basin reached a thickness of ten miles in the area around Bakersfield. Since a great deal of organic material was present in the rock, oil and natural gas accumulated in traps beneath folds and faults.

The are a few spots were animals died in profusion, or where their carcasses accumulated. One of these is exposed at Sharktooth Hill, a privately owned area where a layer, the Round Mountain Silt, included a 3-4 foot thick horizon full of fossils (collecting is allowed with a fee). A few other slopes provide the occasional sharktooth or bone fragments. The origin of the plentiful fossils has long been a source of speculation. Some of the most reasonable explanations involve "red tides", accumulations of algal toxins in the food chain, and turbidity currents, which may have gathered carcasses in specific areas of the seafloor.

There's no experience quite like finding a fossil for the first time. What child hasn't dug in his or her backyard in the hopes of finding prehistoric creatures? The small bit of fish vertebrae or the diminutive shark tooth might well be a Tyrannosaurus rex skeleton for all a student is concerned. It's a good way to start a field studies course.

We didn't find that gigantic tooth at the top of the post, by the way. There are folks who spend days and weeks digging in the ground for specimens. We met a gentlemen who has worked the site for three months. The tooth may very well be from a Carcharodon megalodon, the legendary Great White Shark relative that reached lengths of as much as 60 feet (18 meters). And no, they don't still exist in today's oceans, despite what the Discovery Channel tells you. Isn't a Great White enough in terms of terror?

Out of the Valley of Death: Cutting our (shark) teeth as new geologists

Ropy lenticular cloud, southern Sierra Nevada on the Kern River. Photo by Mrs. Geotripper.

Our recent adventure in Death Valley National Park had some preliminaries. One doesn't just go headlong into the Valley of Death without a bit of preparation. I'm not really talking about survival gear as we face some harsh savage desert, but more preparation of the mind to be able to comprehend the incomprehensible idea of nearly two billion years of geological history. The rock exposures at Death Valley can make geologists from more humid climates cry with awe at the barren naked rock.

Photo by Mrs. Geotripper.

But what if you are a beginning geology student with maybe five weeks of an introductory course under your belt? Approaching Death Valley without some background and context is just begging for absolute information overload. So it was that we quietly introduced our students to the world of geology in a gentle landscape.

We left the previous evening, driving for four hours through the southern San Joaquin Valley. I talk a lot about how interesting the geology is in my home turf, and it is, but frankly, it's as interesting to drive through it at night as it is in the daytime! Maybe even more interesting...

We set up camp late at night at Ming Lake in Kern River County Park. We awoke to a strange ropy looking lenticular cloud off to the east (top of the post), and held our first class in the field, discussing the geography of our journey. We would be passing through a sort of structural nexus of California, with six provinces within view this day: the Great Valley, the Sierra Nevada, the Coast Ranges, the Transverse Ranges, the Mojave Desert and the Basin and Range. We talked about how geologists view a new landscape, establishing the types of rocks, and organizing the layers into formations, members and groups. We discussed the rock we could see from our campsite, and what we might find as we looked at it more closely. We reviewed the fossils that might be discovered. And we talked about Valley Fever.

We had been camping at the base of Sharktooth Hill, and we would have a chance to search for fossils in a formation called the Round Mountain Silt. The silt was deposited in a shallow sea that had existed here for many tens of millions of years in Mesozoic and Cenozoic time. Though the seas were shallow, the sediments were deep in this region, exceeding 50,000 feet. About 20 million years ago, large numbers of sharks and sea-going mammals had died in the region, and their teeth and bones were widely distributed. The number of teeth discovered thus far on Sharktooth Hill proper number in the millions, but the land is privately held (occasional digs are offered through the Buena Vista Museum of Natural History in Bakersfield). We would instead check out some more limited exposures on public land nearby. Some diligent searching usually ends in a few exciting discoveries.

The search was tempered somewhat by the knowledge that the fungal spores that cause Valley Fever have detected in these soils. The students were very cautious about raising any dust, and some wore face masks.

After an hour, a number of students had made some exciting discoveries. For most of them, it was the first time that they had discovered a fossil in place. There are around two dozen species of shark teeth known from these beds, as well as the fragments of bone from marine mammals like dolphins, whales, seals, and large extinct manatee relatives. Upwards of 140 species have been recovered from these layers, making it one of the most significant paleontology localities in the state of California.

My discoveries were modest, a few shark teeth and the tooth of a ray or skate. I spent most of my time helping the others develop the "eye". This usually involves finding a tooth in place, and letting them know it is in an area of a couple of square yards. With the confidence of knowing the tooth is actually there, they usually find it in short order.

With our introduction to geological interpretation complete, we headed across the oil fields of Bakersfield towards Highway 58, Tehachapi Pass, and the Mojave Desert. We were headed towards one of California's greatest state parks, Red Rock Canyon. Our trip had begun in earnest.

Strangers in a Strange Land: Just Getting There is Half the Battle...

And getting back home is the other half....

Death Valley is a heck of a long way from pretty much anywhere. The nearest big city is Las Vegas, 120 miles distant. The small town of Ridgecrest and village of Lone Pine are around 100 miles to the west. From our school, the distance is 400 miles. We only had a holiday weekend to explore the park, so on Thursday evening we packed the vans and drove the first 200 miles in the dark to set up camp near Bakersfield at the south end of the Great Valley. When the sun came up the next day, we would have only 200 miles (with a number of interesting distractions) to get to the park. We would have two full days to explore as much of the park as possible, and then a few stops in the morning on Monday before starting the long road home.

The travelers were community college students, which meant it was a very diverse group of 37 people thrown together into what I like to call a temporary dysfunctional family. There were 'old' people like me, and teenagers, a number of veterans and survivors from last year's trip, and a great many geology neophytes. They were going to learn the basic principles of geology in what I consider the finest way possible: total immersion.

I have to say the nicest thing I can about the quality of these students. If you are a teacher, you know the attitude that students often have, the "teach me, I dare you" look. Enthusiasm is, um, sometimes a rare commodity. It turned out I received a big stack of "Roadside Geology of Northern and Central California" to give away. We were almost packed and ready to go, and I casually mentioned that the books were in the lab, free for the taking. The picture below shows how special these students were...

Luckily, no one was trampled to death.

We arrived at our camp along the Kern River in the southernmost Sierra Nevada near Sharktooth Hill and set up camp in the rapidly dropping temperatures. I know my readers from the northern climes will chuckle, but we Californians really take a beating when we suddenly have to emerge from our homes and cars and start existing at temperatures below freezing. It was cold and damp, too.

But morning came, we packed our gear, and prepared for our geological adventure. This trip was an introduction to how geologists observe the world, so we started at the beginning: we looked at the landscape around us and started asking the basic questions that the first geologists did:

1) What rocks are found here?
2) What processes are acting on these rocks?
3) How did these rocks form, and how did they end up looking the way they do?

What we could see in the low foothills of the Sierra Nevada is that these rocks were not very resistant to erosion. There were no bold cliffs of hard igneous or metamorphic rocks, just gentle soil covered slopes. These rocks were loosely cemented sediments, mostly sand, silt and clay. They were in nearly horizontal layers that allowed us to define the basic unit of geologists: the formation, a distinctive layer of rock that is mappable, and which has definable contacts with the layers above and below. We talked about where these layers might have formed, and how we could tell. The issue of fossils came up, so we were able to talk about how geologists have found some very interesting remains in these hills: some clams and snail shells, and the bones of dolphins, whales, seals, manatee-like species, and many kinds of shark teeth. Clearly, a shallow sea once existed in this place.

The first, and sometimes hardest step in understanding the geological history of a place is to realize how completely a landscape will change over time. 20 million years ago, the Sierra Nevada did not exist as the high mountain range it is today. There were no Coast Ranges off to the west. There was only a shallow sea with a shoreline off to the east. The layers exposed here in the low foothills are called the Temblor Formation and the Round Mountain Silt, and these formations are one of the most famous fossil sources in California.

Not too surprisingly, listening to the talk of fossils caught the attention of the students. It was clear they couldn't wait to see for themselves if there were still fossils to find on the slopes above our campground. We drove a mile down the road, and the great search began.

After a few moments the first bone fragments were found, and then a few shark teeth. Over the next hour, almost everyone had found something of interest. It was a good start to the trip. We climbed back into the vans and headed over the Sierra at Tehachapi Pass, and into the Mojave Desert. Now that we knew what a formation was, we needed to start looking into how we tell the story of a sequence of layers and the various events that happened to them. We were headed to Red Rock State Park to learn the process.

Full disclosure: these are some of the extraordinary teeth that we found last year. I forgot to snap a picture of the fossils we found this year...

The Other California: Sharktooth Hill and a Fossil Collection in Need of a Good Home

Besides the familiar La Brea Tar Pits (translation: "The Tar" Tar Pits), California is not widely known as a treasure trove of fossil discoveries. A little of bit of digging (pun intending) reveals the state as a rich resource of the history of life through time. Death Valley and other parts of the Basin and Range province have been a source of Proterozoic and Paleozoic fossils which are more varied and complete than the assemblage found at Grand Canyon. A few dinosaur bones have been found here and there, but the record of seagoing reptiles is (to me, anyway) even more intriguing: mosasaurs, plesiosaurs and ichthyosaurs. But if you ask paleontologists about the time period with the richest fossil record in California, they may very well mention the Miocene epoch of the Neogene period (5.3 to 23 million years before present). California has some of the thickest sedimentary sequences of Miocene rocks anywhere, including marine and terrestrial environments. A future post may include a discussion of the Ricardo and Barstow formations in the Mojave Desert, but for reasons to be noted in a moment, I want to talk about the Temblor Formation in the Central Valley and Coast Ranges. The Temblor is a sequence of sandstone and siltstone that was deposited in shallow basins offshore in Miocene time, around 15-16 million years ago. A member of the formation, the Round Mountain Silt, is one of the most productive fossil layers in the state.

During the Miocene epoch, the Pacific shoreline lay at the eastern margin of the southern San Joaquin Valley. To the east, where desert landscapes exist today, there was a semi-tropical savanna environment inhabited by camels, horses, tapirs, sloths and elephants. The shallow sea was home to nearly two dozen of species of dolphins, whales, pinnipeds (seals, sea lions and walruses) and other sea-going mammals, including a hippo-like creature called Desmostylus. The fauna also included turtles, crocodiles, and numerous birds. Something needed to fill the slot at the top of the food chain, and given the name of the locality, it isn't too surprisingly a group of sharks. Lots of them; about 27 species of sharks and rays have been discovered here, including the Discovery Channel's favorite, the massive Carcharodon megalodon.

The layers exposed at Sharktooth Hill (along the Kern River upstream of the town of Bakersfield) have yielded up not just thousands of specimens, but hundreds of thousands. In some places, a shovelful of dirt would have hundreds of teeth inside. Numerous studies have been undertaken at the site; a good review can be found here. The national significance of the site was recognized in 1976 as Sharktooth Hill was added to the United States Landmark Registry.

Sharktooth Hill is one of the most important fossil localities in the western United States, and one of the more important fossil collections to have come out of the hill is now being sold by the widow of an amateur paleontologist. The fossils in question have been on public display for a number of years at the CALM Zoo and more recently at the Buena Vista Museum of Natural History. They have hopes of getting the Allodesmus fossil (a primitive sea lion), but the price is too steep for their budget at around $150,000. I hope that some sort of arrangement can be made that will allow the fossil collection to remain accessible to the public. It is a great resource.

The Other California is my continuing series of what to see in our great state when you've visited all the really famous places that show up on all the postcards.