Lisa, Cheryl, Linda, and Cliff
Day 2, Stop 1.5
What captures your attention in these cut-aways next to Hat Creek?
We saw many different layers. Starting from the bottom (which is the oldest), we saw a sandy layer. Directly above that, was a layer of gravel with big rounded rocks – some as big as your head. Above the gravel, there was more sand. The hill was topped with a thick layer of greenish gray rock called dacite. Cutting through all the layers on the hills right side was a layer of chipped brown rock called slate.
How do you think these layers were formed?
We think a river ran through this area first, because the sand was deposited as the bottom layer. Later, there was a flood or swifter flowing river. Imagine -- watching the strong current toss and tumble the big rocks, rounding them and carrying them further downstream. When the flood was over and the river grew calm, sand was again evenly deposited.
Then, off in the distance , a volcano exploded! BOOM! A wall of hot ash raced down at one hundred miles per hour (okay, we weren’t there with a stopwatch…) The heat of the flow welded together the particles in one big greenish gray rock. The green color indicates the presence of the mineral epidote.
Remember the shale fragments? That occurred last because it cut through all the layers. What happened? These fragments slipped from the top of the hill and are believed to be from what is called belt rock which is about 1 billion years old. You can still see knobs of these ancient rocks on the top of the hill today!
How does this compare to the geological features on Mars?
The processes that created this layered formation could possibly have occurred on Mars. Photos of Mars’ surface have shown hills with landslides and volcanic deposits. Currently scientists are searching for more conclusive evidence of past flowing water on Mars. The layer of rounded gravel could only have occurred on Mars if there was indeed flowing water.