Summary of Formation The Sierra Nevada Mountains run 400 miles north and south and 70 miles east and west. One of the most recognizable features is Lake Tahoe and the highest point of the range is Yosemite Valley. This was formed by glaciers that were made up of 100 million year old granite. These are just a few key features in the important formation of the area that is an attraction to so many.
History of Biotic communities The granite that was mentioned before was formed very deep underground. The area of range started to lift upward approximately four million years ago. This caused a major erosion of the glaciers that were exposed to the granite. This began the formation of the many different colored mountain ranges and led to the wide variety of elevations and climates in the Sierra. It is because of this, the five different biotic communities exist.