The document discusses the geology of Lake Tahoe, including its formation around 24 million years ago from lava dams and glacial activity. It also describes the current features of Lake Tahoe such as its depth and size. Several rocks, animals, and plants found in the Lake Tahoe area are also examined, along with their taxonomic classifications and brief evolutionary histories. Key details about the raccoon, black bear, snow flower, granite, and rhyolite are provided.

1. Geology of Lake Tahoe
Nicole Hamilton
Geology 103
Field Assignment

2. 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.).

3. 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.).

4. 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.).

5. 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.).

6. Raccoon
Procyon 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).

7. 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).

8. Black Bear
Ursus 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.).

9. 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).

10. Snow Flower
Sarcodes 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).

11. 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).

12. 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

13. 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