Geology assignment

1. South Lake Tahoe

2. Formation
• Lake Tahoe is 4-5 million years
old it formed by two parallel
fractures in the earth’s crust
causing the basin to sink. The
mountains on each side began to
rise while the valley slowly filled
with water forming the lake.
• 2-3 million years ago volcano
eruptions blocked the north side of
the lake causing the valley to fill
up with water hundreds of feet
above the current elevation today.
• The west side of Lake Tahoe was
covered by large pieces of glacial
ice.

3. • The Large Leaf Lupine
• scientific name is Lupinus
polyphyllus
• Pea family
• color varies from purple to blue
violet.
• This flower grows about 3-5 ft
• It is also very toxic to livestock
• All lupines have compound leaves
meaning that each leaflet
originates from the same point.
They form large enlongated
clusters on the top of each stout.
• This plant is native to western
North America
• Often found in moist habitats
along side river beds, sage brush,
pine forests, and meadows.
Picture by: Audriana Oniell

4. Black Bears
• The bears found in Lake Tahoe are known as the Northwestern black bear also called Ursus
Americana Altifrontalis.
• Lake Tahoe is populated with tons of Black Bears despite their name they can be found in other
colors ex; cinnamon, brown, blonde, blue-grey and white.
• Due to increased fires over the years and humans leaving food out and littering the bears are
prone to dumpster diving and coming into town at any given time.
Pictures By :Audriana Oniell

5. Jeffrey Pine (Pinus Jeffreyi)
• The most common pine tree in
Lake Tahoe
• They live 400-500 yrs
• Jeffrey Pines are very well
adapted to fires in the areas, the
bark is thick and fairly fire
resistant.
Photo by Audriana Oniell

6. Granodiorite
• Medium to coarse
grained intermediate
to acid igneous rock
with essential quartz.
>20% It also has
minor mafic minerals.
The fine grained
equivalent of a
granodiorite is a
dacite.
Photo by :Audriana Oniell

7. Quartz
• The second most common mineral found in the earth’s crust.
• It is made up of silicon, oxygen and tetrahedra with each oxygen
being shared between two tetrahedra.
Photo by Audriana Oniell

8. Basalt
• Very common extrusive igneous volcanic rock
• Formed by rapid cooling of basaltic lava exposed near the surface of the earth.
• It has a glassy matrix look with a mix of minerals.
• Basalt is usually seen as dark color but can be found with a mixture of colors from
weathering.

9. Conglomerate
• Coarse grained
sedimentary rock
made up of substantial
fraction of pebbles,
cobble stones, granule
and boulders.
• They are often
cemented together by
hardened clay, silica,
calcium carbonate,
iron oxide.

10. Diorite
• Grey to dark grey intrusive
igneous rock.
• The salt and pepper texture is
due to the random distribution
of the medium sized grains of
white albite and black
amphibole as well as pyroxene
crystals, minor glints of biotite.
Photo by: Audriana Oniell

11. Sources
• Lake Tahoe Fast Facts. (n.d.). Retrieved June 22, 2015.
• Lake tahoe fault lines - Google Search. (n.d.). Retrieved June 22, 2015.
• Sierra Wild Flowers | Large-Leaf Lupine | Info & Photos. (n.d.). Retrieved June 22,
2015.
• Black Bear Color Phases. (n.d.). Retrieved June 22, 2015.
• (n.d.). Retrieved June 22, 2015.
• Glossary: Granodiorite. (n.d.). Retrieved June 22, 2015.
• (n.d.). Retrieved June 22, 2015, from https://en.wikipedia.org/wiki/Quartz
• (n.d.). Retrieved June 22, 2015, from https://en.wikipedia.org/wiki/Diorite
• (n.d.). Retrieved June 22, 2015, from https://en.wikipedia.org/wiki/Basalt
• (n.d.). Retrieved June 22, 2015, from
https://en.wikipedia.org/wiki/Conglomerate_(geology)
• By :Audriana Oniell