The landscapes and features of Yosemite National Park inspire awe and wonder in the forces that have created such majesty. Geologists, hydrologists, and geographers investigate and document landscapes to get a sense of the ecosystem as a whole that reaches from below 3,000 feet to over 13,000 feet in elevation.

Rock fall is partly responsible for creating Yosemite National Park's beautiful and changing scenery. More than 600 rock falls have occurred in the park during the past 150 years.

Geology: Yosemite presents a glaciated landscape. The scenery, resulting from the interaction of the glaciers and the underlying rocks, was the basis for Yosemite's preservation as a national park. U-shaped canyons, jagged peaks, rounded domes, waterfalls and moraines are all outcomes of glaciation. Glacially-polished granite is further evidence of glaciation and is common in Yosemite National Park. Granite, because of its massiveness and durability, is shaped into bold forms: the cliffs of Yosemite Valley, many of the higher peaks, and the striking sheeted domes that form only in unlayered rock. Rock fall is a dynamic part of the park's geologic past and present, too.

Park hydrologists collect streamflow data to determine snowmelt run-off levels and stream depths along the forceful Merced River.

Hydrology: Most people visiting Yosemite gaze upon the 2,425-foot Yosemite Falls, the tallest waterfall in North America. Water has shaped the Sierra Nevada landscape in the form of glaciers-two of which still remain at Mounts Maclure and Lyell. Spring floods re-shape the land, too, with a natural house-cleaning that scours river channels and re-distributes rock, soil, silt and sand, but summer's lack of water, especially at the lowest elevations, causes some thirsty plants to go dormant in order to survive.

• Measuring Snowpack: Yosemite records snow surveys at 13 different courses with records dating back to 1931. Maximum snow depth at one of Yosemite's snow courses is 232.9 inches in 1969 and maximum water is 96 inches in 1983.
• Volunteer in the park's water quality monitoring effort of the Merced River. Samples test for nitrates and phosphorous. Participate 8 a.m.-5 p.m. the first Wednesday of every month except December and February. Call Katy Warner at 209/379-1421 to sign up.
  

Geography & GIS: New technologies, using complex Geographic Information Systems, go into mapping Yosemite's 750,000 acres. By understanding where concentrations of invasive plants take root or where rock falls occur most frequently, scientists assess management needs, and, in some cases, predict future outcomes. Projections of climate change effects, for instance, reveal why wildlife and plants are moving higher in elevation for suitable habitat. Geography is both a natural and a cultural science. Mapping reveals the relationship, or sense of place, people have with where they live. View national GIS data sets on an NPS Data and Information online clearinghouse, and examine Yosemite's GIS data sets, covering topics from geology to fire to soils. Also, watch a "Yosemite Nature Notes" 10-minute film on Yosemite maps that portrays the physical and cultural landscape of the park.

Wilderness: Wilderness, 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, no modern conveniences. Nearly 95 percent of Yosemite is Congressionally designated as 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.
• Plan to attend the Yosemite Forum, monthly lectures in the Valley open to the public.