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A Field Assignment in Yosemite NP By Gregory Hoover

Field assignment in yosemite

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Page 1: Field assignment in yosemite

A Field Assignment in Yosemite NP

By Gregory Hoover

Page 2: Field assignment in yosemite

Brief Geologic History of Yosemite

• Yosemite is part of the Sierra Nevada mountain range, which lies along a fault and was created through several periods of uplift and tilting to the west; this process is ongoing even today

• Beginning in the Mesozoic, large amounts of magma rose to the surface and cooled as granite

• By the beginning of the Cenozoic, the magma flow ceased and the enormous mass of granite called the Sierra Nevada monolith was in place

• Numerous uplift and erosion events, combined with glaciation, have created Yosemite’s present landscape

• Granite dominates the region and the park

• Only 5 % of the rock in the park is metamorphic

(King, 1987)

Page 3: Field assignment in yosemite

Yosemite’s massive granite features

• El Capitan is one of Yosemite’s best known rock formations, rising 3,593 feet from the Valley floor (www.nps.gov/yose)

Images courtesy of author

Page 4: Field assignment in yosemite

• Granite is the most common type of intrusive igneous rock

• Granite is considered to be felsic, or containing more than 65% silica

• Granite is a coarse or medium-grained, crystalline igneous rock, composed mostly of quartz and feldspar

• The granite in Yosemite is mostly plutonic and was formed when underground magma cooled very slowly, which allowed the large crystals to form

• Granite is extremely durable

(Monroe and Wicander, 2009)

Characteristics of Granite

Above: Half DomeLeft: Close up of granite at Olmstead Point

Images courtesy of author

Page 5: Field assignment in yosemite

Metamorphic rock in Yosemite• As mentioned previously, only 5% of

the rock in Yosemite is metamorphic

• Layered metamorphic rocks exist at the western edge of the park and at the eastern edge near the summit area of the park (King, 1987)

• These ancient rock formations are remnants of sedimentary and volcanic rock that experienced deformation and metamorphosis, partly due to intrusions by granitic rock (King, 1987)

• One such area is Mt. Dana, near the Tioga Road Entrance

Mt. Dana. Image courtesy of author

Page 6: Field assignment in yosemite

Ecology of Yosemite

• Yosemite supports and hosts a wide variety of plant and animal species that have evolved to survive in the high desert and high altitude

• Plants and animals have also evolved to survive the harsh winters in Yosemite

• Among these plants and animals are the mule deer, the black bear, and the sequoia tree

Page 7: Field assignment in yosemite

The Mule Deer: Origins• Found from the middle of the United States to the

west coast and from Mexico up through parts of Canada and Alaska

• Mule deer originated from a primitive deer that came from Asia over a million years ago

• It was named in 1804 by the Lewis and Clark expedition because their ears resembled those of a mule

• The scientific name is Odocoileus hemionus (Odocoileus= hollow tooth and hemionus= half-mule)

• Mule Deer are closely related to the eastern white-tailed deer, and also related to the moose, elk, and caribou

(Wasley, 2004)Images courtesy of author

Page 8: Field assignment in yosemite

The Mule Deer: Adaptations• Mule Deer move in stiff-legged jumps with

all four feet hitting the ground at once; they can cover distances up to 8 yards

• This allows the mule deer to out-distance their predators in rough terrain

• It also allows them to see over thick sagebrush

• They can also turn or reverse direction in a single bound

• Their muted gray allows them to blend into their surroundings and helps them evade predators like the mountain lion, the coyote and the eagle

• The Mule Deer has larger feet than the other deer species which helps them to dig for water as great as two feet underground

(Nevada Dept of Wildlife, 2010)

Image courtesy of author

Page 9: Field assignment in yosemite

The Mule Deer: Adaptations

• Mule Deer have a multi-part stomach; the first two stomachs temporarily store food that can be digested later

• Their long necks and the location of their eyes (on the sides of their heads) allow them to see in every direction, except directly behind them

• Their large ears, which are about two-thirds the length of their head, allow for a keen sense of hearing; in comparison, a white-tailed deer’s ears are only one-half the length of its head

• Their fur is made up of hollow hair that gives them greater insulation from cold winters

(Nevada Department of Wildlife, 2010)

Page 10: Field assignment in yosemite

Evolutionary history of the Black Bear

Black bears and brown bears share a common ancestor but evolved separately around 2.5 million years ago, as the flowchart shows

Image courtesy of the University of California BerkeleyAbove image courtesy of author

Page 11: Field assignment in yosemite

The Black Bear• Over the course of the last few ice ages, black bears and many other

species of the Pleistocene fauna were forced south due to expanding ice sheets

• The American black bear is found all throughout North America, from

Canada to Mexico

• Modern black bears are much smaller than their prehistoric ancestors

• Though they are primarily found in forested areas, black bears are extremely capable of adaptation and can thrive in many habitats

• Eastern populations of black bears are usually black in color

• Western populations have fur that is often brown, cinnamon, and blond, in addition to black

(Craighead Institute, 2010)

Page 12: Field assignment in yosemite

Adaptations of the Black Bear

• Ancient black bears could not compete with large cats for prey and they were not big or strong enough to drive them away from kills, so they adapted by eating fruits, honey, insects, plants, and smaller prey

• Their claws are curved to allow them to climb trees for security; they climb to avoid danger and mother bears teach their cubs to climb trees while the mother has to forage

• They have long tongues and dexterous toes that enable them to have access to food inside rotten logs

• (Craighead Institute, 2010)

Page 13: Field assignment in yosemite

The Giant Sequoia

• The giant sequoias are the third oldest living trees in the world

• They can live to be more than 3000 years old

• They have evolved several adaptations that has helped them survive this long

Image courtesy of author

Page 14: Field assignment in yosemite

Adaptations of the Giant Sequoia• The giant sequoia relies on fire to help it reproduce; the hotter the

fire, the greater the chance of seedlings germinating

• It has developed a cone that helps preserve seeds and also means that animals will help in seed dispersal

• The scales of the cones actually serve as a food source to squirrels and beetles, lessening the chance of animals and insects eating the seeds inside

• Thick bark helps the giant sequoia survive fire

• The giant sequoia also loses its lower branches when they become too heavy so that it eventually becomes branchless for up to 125 feet off the ground, further protecting it from fire

(Harvey, 2007)

Page 15: Field assignment in yosemite

References• Craighead Institute. (2010). “The American Black Bear.” Retrieved from

www.grizzlybear.org.

• Harvey, H. (2007, March). Giant Sequoia Ecology: Fire and Reproduction. In National Park Service. Retrieved July 19, 2011

• King Huber, N. (1987). The Geologic Story of Yosemite National Park. Washington, DC: United States Government Printing Office.

• Monroe, J. S., & Wicander, R. (2009). The Changing Earth (5th ed., pp. 348-352). Belmont, CA: Brooks/Cole, Cengage Learning.

• Nevada Department of Wildlife. (2010). “Nevada Fauna Facts: Mule Deer.” Retrieved from www.ndow.org/wild/animals/facts/mule_deer.shtm.

• Wasley, T. (2004, August). Mule Deer Population Dynamics: Issues and Influences. In Nevada Department of Wildlife. Retrieved July 19, 2011