Today, Yosemite Creek flows over the Yosemite Valley rim to create Upper Yosemite Fall. Before its diversion about 130,000 years ago, Yosemite Creek flowed down an older channel just to the west, from which it cascaded down through the steep ravine that is now the route of the Yosemite Falls Trail.[3]
Hydrology
The Yosemite Creek watershed, which feeds the creek and Yosemite Falls, contains 43 square miles (110 km2). It is largely a granite basin that was scraped clean of soil by glaciers. Because of the shallow soil base, the Yosemite Creek watershed has little capacity to hold water, so it quickly drains as the snow melts.[4]
^U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. The National MapArchived 2012-03-29 at the Wayback Machine, accessed March 11, 2011