Geology of Lake Tahoe

Nicole Hamilton

Geology 103Field Assignment

Formation of Tahoe• Around 24 million years

ago the Sierra Nevada formed by faulting.

• Lava from Mt. Pluto formed a dam which water from snowmelt and stream made a larger lake than today’s.

• Migrating glaciers formed V-shaped canyons into U-shaped valleys (Geology of the Lake Tahoe Basin, n.d.).

The Lake of Tahoe• Lake Tahoe is the third

deepest lake in North America, tenth in the world.

• Twenty-two miles long and twelve miles wide.

• Greatest measured depth is 1,645 feet.

• Fun fact: The bottom of the lake is at a lower elevation than Carson City, Nevada (Geology of Lake Tahoe Basin, n.d.).

Igneous-Rhyolite• I believe this rock to

be Rhyolite.• Rhyolite is a

volcanic rock composed mostly of felsic.

• It’s said to have some resemblance to granite.

• It forms at low temperatures with a high percentage of silica (Nave, n.d.).

Igneous-Granite• I believe this rock to be

Granite.• Granite is a course rock

with large amounts of feldspar and quartz.

• Granite is also the most abundant rock in the continental crust.

• It forms when magma’s crystallization is slow beneath the surface (Granite, n.d.).

RaccoonProcyon lotor• Raccoons can be found all

over the United States except for Central Nevada, Rocky Mountains, Utah, and Arizona.

• Omnivorous • Mostly nocturnal• Easily identifiable by their

black mask and ringed tail (Raccoon, 2013).

• Raccoons are part of the Carnivora order and Procyonidae family (Raccoon, wiki).

Raccoon Evolution

• Animalia => Chordata => Mammalia => Carnivora => Procyonidae => Procyon => P. lotor

• Carnivora evolved from Miacidae around the middle and late Eocene, from both North America and Eurasia (Carnivora, wiki).

• The first known members Procyonidae lived in Europe in the late Oligocene about 25 million years ago.

• The common ancestor of the raccoon is said to have left tropical areas around 2.5 million years ago (Raccoon, wiki).

Black BearUrsus americanus• American Black Bears are

part of the order Carnivora and a part of the Ursidae family (American Black Bear, wiki).

• They range from Alaska to Canada, and down to Mexico.

• Black Bears are omnivores, eating both meat and plants it finds in the forest.

• They can run up to 30 miles per hour, and are crepuscular (American Black Bear, n.d.).

Black Bear Evolution

• Animalia => Chordata => Mammalia => Carnivora => Ursidae => Ursus => U. americanus

• Ursus abstrusus is the oldest known North American fossil member of Ursus from nearly 5 million years ago.

• The earliest American black bear fossils were found in Port Kennedy, Pennsylvania.

• A wider variety of foods helped the American black bear survive the ice age 10,000 years ago (American black bear, wiki).

Snow FlowerSarcodes sanguinea• Snow flowers are parasitic

of fungus living under the ground or wet soil.

• They appear after the snow melts or has mostly melted.

• It ranges from California to western Nevada.

• The stamen inside the petals collect pollen, which it later shakes out or develops fruit inside of it (Sarcodes sanguinea, n.d.).

• Snow flowers are part of the order Ericales and the family of Ericacaea (Sarcodes, wiki).

Snow Flower Evolution

• Plantae => Angiosperms => Eudicots => Asterids => Ericales => Ericaceae => Sarcodes => S. sanguinea

• The earliest angiosperm macrofossil is dated to 125 million years ago (Angiosperm, wiki).

• Ericacaea have a wide range, including Antartica, Greenland, Australia, and the Americas (Ericacaea, wiki).

• S. Sanguinea is found in most of California and western Nevada (Sarcodes, wiki).

References

Geology of the Lake Tahoe Basin. (n.d.). In Lake Tahoe Basin Mgt Unit - Learning Center. Retrieved June 18, 2013, from http://www.fs.usda.gov/detail/ltbmu/learning/?cid=stelprdb5109570

Raccoon. (2013). In Nature Works. Retrieved June 19, 2013, from http://www.nhptv.org/natureworks/raccoon.htm

Raccoon. (n.d.). In Wikipedia. Retrieved June 18, 2013, from http://en.wikipedia.org/wiki/Raccoon

American Black Bear. (n.d.). In Wikipedia. Retrieved June 20, 2013, from http://en.wikipedia.org/wiki/American_black_bear

American Black Bear. (n.d.). In Nature Works. Retrieved June 19, 2013, from http://www.nhptv.org/natureworks/blackbear.htm

Sarcodes sanguinea. (n.d.). In Botanical Society of America. Retrieved June 20, 2013, from http://www.botany.org/parasitic_plants/Sarcodes_sanguinea.php

Sarcodes. (n.d.). In Wikipedia. Retrieved June 20, 2013, from http://en.wikipedia.org/wiki/Sarcodes

Nave, R. (n.d.). Rhyolite. Retrieved June 18, 2013, from http://hyperphysics.phy-astr.gsu.edu/hbase/geophys/rhyolite.html

Granite. (n.d.). In Geology.com. Retrieved June 18, 2013, from http://geology.com/rocks/granite.shtml

Carnivora. (n.d.). In Wikipedia. Retrieved June 21, 2013, from http://en.wikipedia.org/wiki/Carnivora

Angiosperms. (n.d.). In Wikipedia. Retrieved June 21, 2013, from http://en.wikipedia.org/wiki/Angiosperms

Ericaceae. (n.d.). In Wikipedia. Retrieved June 21, 2013, from http://en.wikipedia.org/wiki/Ericaceae