The Alabama Hills (in the foreground and middle ground) are dominantly chemically-weathered granites, contrasting distinctly with the physically-weathered granites of the Sierra Crest in the distance. There are a number of reasons for the different weathering patterns. One reason is the lower slope in the valley bottom results in less physical erosion, allowing time for the chemical weathering to dominate and allowing soils to build up on top of the rocks. Another reason is that the valley bottom was not covered by glaciers during the last ice age. Glaciers tend to denude the landscape and leave plenty of fresh rock exposed to the elements...