Yosemite Creek Yosemite Creek Yosemite Creek is a creek of the Sierra Nevada, located in Yosemite National Park, Mariposa County, California. The creek's headwaters are at the Grant Lakes (), and it flows southwest to drop over Yosemite Falls to Yosemite Valley, then flows southeast to its mouth at the Merced River, just southwest of Yosemite Village. () The Merced is a tributary of the San Joaquin River, in the San Joaquin Valley. 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
Yosemite National Park Starting 20 million years ago (in the Cenozoic) and lasting until 5 million years ago, a now-extinct extension of Cascade Range volcanoes erupted, bringing large amounts of igneous material in the area. These igneous deposits blanketed the region north of the Yosemite region. Volcanic activity persisted past 5 million years BP east of the current park borders in the Mono Lake and Long Valley areas. Starting 10 million years ago, vertical movement along the Sierra fault started to uplift the Sierra Nevada. Subsequent tilting of the Sierra block and the resulting accelerated uplift of the Sierra Nevada increased the gradient