Natural Features & Ecosystems

Yosemite National Park inspires awe and wonder at the forces that have created its dramatic landscapes. Geologists, hydrologists, and geographers investigate and document the processes that shape them in order to get a holistic sense of this diverse ecosystem and environment, which ranges from below 3,000 feet to over 13,000 feet in elevation.
Ranger holds tool above rock fall rubble
Rockfall is partly responsible for creating Yosemite National Park's beautiful and constantly changing scenery. More than 600 rockfalls have occurred in the park during the past 150 years.

Geology: Yosemite is a classic example of a glaciated landscape, where glaciers have carved the smooth domes of Tuolumne Meadows, the jagged high country peaks, and the dramatic walls of Yosemite Valley. This scenery was the basis for Yosemite's preservation as a national park. Granite, because of its durability and strength, preserves these bold forms. While glaciers have retreated from all but the highest peaks, Yosemite’s iconic cliffs continue to be shaped today by rockfall and other erosive processes.

  • Plan to attend the Yosemite Forum, monthly lectures in the Valley open to the public.

Ranger stands alongside river with water tester
Park hydrologists collect streamflow data to determine snowmelt run-off levels and stream depths along the forceful Merced River.

Hydrology: Yosemite is famous for its waterfalls, particularly the 2,425-foot Yosemite Falls—North America’s tallest. However, water shapes this landscape in myriad other ways. Winter snowpack is a major driver of the park’s hydrologic system, so it is carefully measured at 13 different courses with records dating back to 1931. Spring floods reshape the land during a natural house-cleaning that scours river channels and redistributes rock, soil, silt, and sand. Dry summers, especially at the lowest elevations, force plants to adapt to a lack of water and the presence of fire.

Geography & GIS:
Geography is both a natural and a cultural science, just as Yosemite is a site of incredible natural beauty as well as a rich cultural history. Mapping reveals the relationship people have with the spaces they inhabit. Complex mapping software, called geographic information systems, allows park scientists to carefully map and analyze Yosemite's 750,000 acres. By understanding where rockfalls occur most often or how fire behaves in these forests, scientists can assess management needs and protect the park and the people within it. Projections of climate change effects, for instance, reveal why wildlife and plants are moving higher in elevation to find suitable habitat.

  • View national and Yosemite GIS datasets on an NPS Data Store.
  • Watch a Yosemite Nature Notes 10-minute video on Yosemite maps that portrays the physical and cultural landscape of the park.

Wilderness: Wilderness is a place unchanged by people: a place of solitude, a place of peace, a place of adventure and learning. Here, you will find no cars, no roads, no electricity, and no modern conveniences. Nearly 95 percent of Yosemite is congressionally designated wilderness, which, "in contrast with those areas where man and his own works dominate the landscape, is an area where the earth and its community of life are untrammeled by man, where man himself is a visitor who does not remain."

  • Learn more about Yosemite's Research and Studies, including ecosystem conditions affecting lichen and black oak tree growth, and animals like the Sierra Nevada yellow-legged frog.
  • Watch a Yosemite Nature Notes video on wilderness.
“I gloried in the magnificent setting in which I found myself, with crystal-clear lakes set in glacial basins adjacent to massive Mounts Ritter and Banner and the jagged Minarets of the Ritter Range—all of this and absolutely fascinating geology … sitting around the campfire … or lying on an outcrop watching shooting stars.” –N. King Huber, U.S.G.S. scientist and author of Geological Ramblings in Yosemite

Contact the Park

Mailing Address:

PO Box 577
Yosemite National Park, CA 95389


(209) 372-0200
The public information office is open from 9 am to 5 pm Pacific time (closed for lunch). Once connected, dial 3 then 5. If the ranger is already on the line, you'll be returned to the main menu. If the ranger is not there, you can leave a message and we will return your call.

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