How did Half Dome, the massive rock monument in Yosemite National Park, acquire its unique shape?

At the head of the valley in Yosemite National Park - as if on a pedestal - stands Half Dome. It is smoothly rounded on three sides and a sheer vertical face on the fourth. Half Dome, which stands nearly 8,800 feet (2,682 meters) above sea level, is composed of granodiorite, and is the remains of a magma chamber that cooled slowly and crystallized thousands of feet beneath the Earth's surface. The solidified magma chamber - called a pluton - was then exposed by uplift and erosion of the overlying rock. As the overlying rock eroded, the confining pressure on the pluton was removed and a type of weathering called exfoliation slowly created the more rounded appearance of the dome. At the same time, weathering along vertical joints created the steep northwest face. Later glaciation continued the process by undercutting and plucking rock from the already steep face. The processes of weathering continues to this day as shown by the many rock falls which occur within Yosemite Valley.

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What is a landslide and what causes one?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further...

Are today's glaciers leftovers from the Pleistocene ice age?

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Is glacier ice a type of rock?

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Where can I find information about the geology and natural history of National Parks?

Our National Parks are the showcases of our nation's geological heritage. The National Park Service has websites for most individual parks which include information about their geology and natural history. A source of information from the USGS is our Geology and Ecology of National Parks website. The website has listings for regions of the country...

What is the difference between a rock and a mineral?

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What are igneous rocks?

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Date published: March 28, 2016

Hot Days Can Trigger Yosemite Rockfalls

After more than three years of monitoring the towering granite cliffs of Yosemite National Park, scientists have new insights into a potentially important mechanism that can trigger rockfalls in the park. Although many conditions can trigger rockfalls, some rockfalls are more likely to happen in the hottest part of the day, during the hottest part of the year.

Date published: June 12, 2012

Yosemite National Park and U.S. Geological Survey Publish Quantitative Rockfall Hazard and Risk Assessment for Yosemite Valley

Yosemite National Park and USGS scientists, in collaboration with academic geologists, recently completed a comprehensive study of rockfall hazard and risk in Yosemite Valley.  

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Image shows Yosemite Valley shrouded in fog.
April 18, 2016

Yosemite Valley

Yosemite National Park, part of the Sierra Nevada range. Credit: Alex Demas, USGS.

Image: Scientists Collect Data on Yosemite Rock Erosion
March 15, 2016

Scientists Collect Data on Yosemite Rock Erosion

Yosemite National Park geologist Greg Stock and USGS civil engineer Brian Collins download data from instruments measuring how much granitic exfoliation sheets move from daily temperature variations as a precursor to rock fall.

Image: Yosemite Falls and Half Dome Panorama
March 10, 2014

Yosemite Falls and Half Dome Panorama

In this panorama, Yosemite Falls may be seen on the left and Half Dome on the right. Yosemite Falls is the tallest known waterfall in North America, with a total plunge of 2,425 ft (739 m). Half Dome is a granite dome, part of the Sierra Nevada batholith.

Image: Manzanita with Half Dome
March 10, 2014

Manzanita with Half Dome

In this image, a manzanita shrub may be seen with Half Dome behind it. Manzanitas are evergreen shrubs with orange or red bark.

Image: Yosemite Falls-All Three Sections
March 9, 2014

Yosemite Falls-All Three Sections

In this image, all three sections of Yosemite Falls can be seen. Yosemite Falls is the highest measured waterfall in North America at 2,425 ft (739 m) in height. Yosemite Falls is one of the most famous waterfalls within Yosemite National Park.

Image: Moon over Half Dome Panorama
March 9, 2014

Moon over Half Dome Panorama

In this image, the Moon may be seen in panorama rising over Half Dome. Half Dome is a granite dome, rising about 4,737 ft (1,444 m) above the surrounding valley. It is part of the Sierra Nevada batholith and is one of Yosemite National Park's most famous features.

Image: Moon over Half Dome Detail
March 9, 2014

Moon over Half Dome Detail

In this image, the Moon may be seen in detail rising over Half Dome. Half Dome is a granite dome, rising about 4,737 ft (1,444 m) above the surrounding valley. It is part of the Sierra Nevada batholith and is one of Yosemite National Park's most famous features.

Image: Moon over Half Dome
March 9, 2014

Moon over Half Dome

In this image, the Moon may be seen rising over Half Dome. Half Dome is a granite dome, rising about 4,737 ft (1,444 m) above the surrounding valley. It is part of the Sierra Nevada batholith and is one of Yosemite National Park's most famous features.

Image: Half Dome from Cathedral Spires
March 9, 2014

Half Dome from Cathedral Spires

In this image, Half Dome may be seen from the base of Cathedral Spires. Half Dome is a granite dome, rising about 4,737 ft (1,444 m) above the surrounding valley. It is part of the Sierra Nevada batholith and is one of Yosemite National Park's most famous features.