What Aren't We Seeing?
September 10, 2005 1:22 AM Subscribe
What Aren't We Seeing? Panoramic (high-res) Photographs of Profound Geological Erosion. When we're in Monument Valley, it's tempting to say that we're looking at monuments - large hunks of stone scattered across the landscapes like statues to honor past heroes, or tombstones to honor the dead. A closer look tells us there's more to it than that. As we scan from one "monument" to the next, we can see in each monument a sloping base of roughly uniform vertical thickness and then straightsided rock of very uniform thickness. The rock is the same in all of them, suggesting that they were all part of two (or many more) uniform layers of stone that extended across the entire region. And how about here, where the Front Range and the Great Plains meet. Do you see a fault? An experienced geological observer would see a high ridge to the left with at most a few scattered ragged exposures of rock, whereas a prominent ridge of sedimentary rock juts up in the middle but is nowhere to be seen to the left. The road that we see going away from us on the left side of the image seems to separate two rather different areas. That observation provides us with a hypothesis: maybe there's a fault between two different kinds of rock. (more discussion here, and don't miss the Virtual Field Trip to a Major Unconformity).
This thread has been archived and is closed to new comments