The trees in Yosemite Valley are about 300 years old. Nobody claims, of course, that Yosemite Valley is that young. Yet the evidence from trees, and other evidence, shows that Yosemite Valley is much younger than sometimes stated. While the formation is often ascribed to glacial action, it seems likely that it, like many other features of the Earth's surface, may have been caused by the violent erosion which happened at the end of the Flood, in conjunction, perhaps, with earthquakes.