Thursday, February 23, 2012

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...
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