Monday, June 17, 2013
The First Stage of our Journey: Basic Principles
We are into our third day on our journey through the Colorado Plateau, and yesterday we actually reached the plateau. We needed to get out of the Central Valley, cross the Sierra Nevada, and then make what once was a terrifying traverse of the dreaded Mojave Desert. My family recounts the difficulty of driving the Mojave in the immediate aftermath of the Great Depression, with long steep grades on Route 66 that were driven primarily at night for fear of overheating the radiator system of the old Ford. It was of course worse for colonists in covered wagons. To the Paiute people, it was simply home.
For us it was a pleasant drive (for once), as we had cooler weather than normal, and no serious accidents on the highway causing delays. We had the time to explore one of my favorite teaching sites in the region, Rainbow Basin National Conservation Area.
The basin exposes the colorful beds of the Miocene Barstow Formation, and the rocks have a rich record of fossil discoveries, including early species of elephants, horses, camels, bear-dog ancestors, cat ancestors, and even multitudes of insects and arachnids. But best of all, it is a place to learn the basic principles of geology.
We talked about Steno's principles of stratigraphy and cross-cutting relationships, and the students set about telling the sequential story of the outcrop seen above. Can you do it? Can you lay out a sequence of events that tells the story of how this rock came to be the way it is? I'm glad to say the students did pretty well, especially since this exposure is our SLO exercise (student learning outcome).