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Yosemite
National Park
Yosemite lands were first preserved by
the United States Congress and President Abraham Lincoln
who, in 1864, at the height of the American Civil War, granted
them to the people of California for preservation. At that
time, the federal government was very limited in size and
wealth, and the concept of a "national park" had
not yet emerged, so authorizing California to preserve these
federal lands seemed appropriate. This original land grant
comprised just under 39,000 acres (15,500 hectares), or
about 60 square miles, and included Yosemite Valley and the Mariposa Grove of giant sequoias. In 1890, Yosemite
was added to the new national park system that had begun
with the preservation of Yellowstone National Park in 1872.

The park's 200 miles (320km) of roads give access to many
of its features by private vehicle and in some areas by
free shuttle bus. To get to know the real Yosemite,
however, leave your car or shuttle bus and travel even a
short distance on a trail. You don't have to go far to discover
the grandeur that can be found here and the values this
special place offers. Millions of people have come to Yosemite and left refreshed and relaxed and perhaps a bit more knowledgeable
about what they want out of life.

Yosemite
Valley is at the center of most visitor activity
in Yosemite National Park. The Merced River
flows across the Valley's flat floor at an elevation (altitude)
of 4,000 feet (1220m) above sea level. The Valley floor
includes oak and mixed-conifer woodlands and numerous meadows,
inhabited by diverse wildlife. The Valley is surrounded
by steep, almost vertical, granite cliffs, including the
El Capitan monolith, Glacier Point, and Half Dome. Major
waterfalls tumble into the Valley, the most prominent of
which are Yosemite, Bridalveil, and, less
easily seen from below, Vernal, Nevada, and Illilouette.
The falls reach their maximum flow in late spring and drop
significantly in flow as the season progresses.

The
exposed geology of the Yosemite area includes
primarily granitic rocks with some older metamorphic rock.
The first rocks were laid down in Precambrian times, when
the area around Yosemite National Park was on the edge of a very young North American continent.
The sediment that formed the area first settled in the waters
of a shallow sea, and compressive forces from a subduction
zone in the mid-Paleozoic fused the seabed rocks and sediments,
appending them to the continent. Heat generated from the
subduction created island arcs of volcanoes that were also
thrust into the area of the park. In time, the igneous and
sedimentary rocks of the area were later heavily metamorphosed.
Yosemite
National Park photo gallery |
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Most
of the rock now exposed in the park is granitic, having
been formed 210 to 80 million years ago as igneous diapirs
6 miles (10 km) below the surface. Over time, most of the
overlying rock was uplifted along with the rest of the Sierra
Nevadas and was removed from the area by erosion. This exposed
the granitic rock to much lower pressure, and it was also
subjected to erosion in the forms of exfoliation and mass
wasting.
Starting
about 3 million years ago a series of glaciations further
modified the area by accelerating the erosion. During that
time large glaciers periodically filled the valleys and
canyons. Landslides and river erosion have been the primary
erosive forces since the end of the last ice age, which
ended in this area around 8000 BC.
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Yosemite Falls is the highest measured waterfall in North
America. Located in Yosemite National Park in the Sierra Nevada mountains of California, it is a major
attraction in the park, especially in late spring when the
water flow is at its peak.
The
total 2425-foot distance from the top of the upper falls
to the base of the lower falls qualifies Yosemite Falls
as the 6th highest waterfall in the world (with the recent
discovery of Gocta Cataracts it presently appears on some
lists as the seventh). Although often referred to as a "two-stage
drop", the falls actually consist of three sections.
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