which granite forms is important in determining what kind of granite develops, and in the case of Yosemite our knowledge of this has left us with certain mysteries. When we look at the very ancient pre-granite Yosemite rocks, we find that some of them came from distant sources, and we cannot decipher the evolution of the Yosemite landscape without considering these sources and the processes which were involved in transporting these rocks to the Yosemite area. Events that happened thousands of miles away had an impact on western North America.
The vast beauty of Yosemite, which we enjoy today, has a history, and that history extends back millions of years. Scientists can read this history in the rocks, the formations, and the geologic activity of the area. Valley View at Yosemite provides a breathtaking glimpse of the size and grandeur of the valley. From that vantage point today, you can see such massive and beautiful formations as El Capitan on the left and Cathedral Rocks and Bridalveil Fall on the right. The valley is U-shaped, and the bottom of the U is much flatter than is typical in glacially carved valleys. The reason for this is that the bedrock surface, the surface formed by hard rock, is almost 2,000 feet beneath the present floor of the valley between El Capitan and Cathedral Rocks. The present valley floor is a plain formed by partial filling of the valley by lake and stream sediments.
The sheer walls of El Capitan rise 3,000 feet above the floor
of the valley. This and the walls of Cathedral Rock reflect both
the massive nature of the rocks (with an absence of joints or fractures) and the glacial erosive processes that shaped Yosemite Valley. Just north of Valley View today joints in the rock are more abundant so that the sloping cliffs are covered with talus blocks and the valley is wider (Harbaugh 53-54). The history of Yosemite tells us how the view we enjoy today was created.
The oldest rocks to be fou...