The Lake Tahoe Basin formed over millions of years through the movement of tectonic plates and glacial activity. Approximately 670 million years ago, the area was a shallow sea. As the plates collided and pushed against each other over 130 million years, lava plumes rose and granite formed. Around 10 million years ago, faults caused the Sierra Nevada to rise, creating the valley where Lake Tahoe now sits. The last ice age, ending 10,000 years ago, shaped features like Emerald Bay through glacial activity. Today, the area is surrounded by granite peaks and contains diverse plant and animal life.

1. By: Victoria Luquin
Disclaimer: Unless otherwise
specified, all photos are taken
by author.

2. How did the Tahoe Basin Form?
“The Lake Tahoe Basin began to form around 670 million years ago and at that time, the area that is now the Basin
was a shallow sea and part of the super continent Pangaea. Sediment slowly deposited on the floor of the shallow sea
for hundreds of millions of years creating a block of sedimentary rock. Nearly 210 million years ago the North
American Continental Plate broke off from Pangaea and began to drift west. At the same time, the Pacific Ocean Plate
beneath the ocean began to drift east. The plates crashed together and the pressure pushed the Pacific Ocean Plate
under the North American Plate. Over the next 130 million years the increased pressure and temperature from the
colliding plates caused rock to melt and form plumes of lava that began rising toward the surface of the earth
thousands of feet below the sedimentary rock. The long, slow cooling process allowed crystals to form and create the
granitic rock seen in the Sierra Nevada. Tops of the lava plumes pushed through the rock leaving outcrops of altered
sedimentary rock, called metamorphic rock. Then, approximately ten million years ago, the Sierra Nevada granitic
rock broke through the surface of the earth after an active fault along its eastern side caused it to rapidly rise. Two
additional active faults on the east and west side of what is now Lake Tahoe created a valley floor that dropped
thousands of feet below the mountain ranges. The last ice age started approximately three million years ago and
ended ten thousand years ago. The Sierra Nevada was not affected by continental ice sheets but did experience
mountain glaciations. Dams were created by glaciers pushing rocks into piles that formed areas like Emerald
Bay, Cascade Lake and Donner Lake in the Lake Tahoe Region” (Hill, M).

3. Views from Emerald Bay

6. View from Eagle Falls

10. The pictures I have of the rocks were ones that I took as I
walked the trails at Emerald Bay and Eagle Falls. I have never
actually been up to this area in the whole 17 years I’ve lived in
South Lake Tahoe, but I definitely plan on going again soon.
The view is amazing!

11. Rock: Sample 1
“The peaks that surround Lake Tahoe
are mountains of granite. Granite is a
light gray, medium to coarse-grained
rock. It is prevalent in the Sierra
Nevada Mountains, along with other
igneous rocks and metamorphic
slate. Granite is composed of two
light-colored minerals, quartz and
feldspar. Some granite appears to be
salt and pepper in appearance due to
the presence of darker colored
minerals such as iron and
magnesium” (The Lake Tahoe Basin).

12. Rock: Sample 2
I believe that these are also
samples of granite. Although the
top right sample seemed to have a
different, and much darker
appearance at first it does have the
“pepper” appearance like the rest.

13. “Igneous Rock is formed when a magma cools underground and
crystallizes or when it erupts unto the surface of the ground, cools
and crystallizes. Magma that erupts onto the surface is called lava.
When magma cools slowly underground the crystals are large
enough to see. When it cools quickly on the surface, the crystals
are very small and you would need a magnifier or a microscope to
see them. Sometimes, when the magma cools very quickly, it forms
a kind of black glass that you cannot see through” (Peck, D).

14. Rock: Sample 3
My best attempt at identifying the
rocks in this picture lead me to believe
that these rocks are the sedimentary
rock sandstone.

15. “Sedimentary Rock forms from particles, called sediment, that are
worn off other rocks. The particles are sand, silt, and clay. Sand has
the largest particles while clay has the smallest. If there are a lot of
pebbles mixed with the sand, it is called gravel. The sediment gets
turned into rock by being buried and compacted by pressure from the
weight above it. Another way it becomes rock is from being cemented
together by material that has been dissolved in water. Often, both
cementing and compaction take place together” (Peck, D).

16. The following pictures of plants are all pictures that I captured on the walk on the trail. I
chose to capture more pictures of flowers because it is obvious that we are surrounded
by trees here in Lake Tahoe, so I figured I’d take advantage of the nice change of view.
While searching for identifications for the plants I took pictures of, I was unable to find
any information on the evolution they have gone through. Some of the other plants
that are common in the area are: “TREES: Alder, Aspen, Cedar, Jeffrey Pine, Lodgepole
Pine, Ponderosa Pine, Sierra Juniper, Sugar Pine, White Fir, Willow. WILDFLOWERS BY
COLOR: Blue & Purple: Dwarf Alpine Aster, Lupine, Meadow Penstemon; Pink & Red:
Columbine, Indian Paintbrush, Shooting Star, Snow Plant, Thistle; White: California Corn
Lily, Common Yarrow, Cow Parsnip, Mariposa Lily, Ranger Buttons; Yellow:
Buttercup, Mountain Mule Ears, Sulphur Flowers” (The Lake Tahoe Basin).

17. Plant: Sample 1
The identification I have
found for this plant is that it
is mountain spiraea. It is a
pink plant that looks kind of
fuzzy. It is a dense branching
shrub.

18. Plant: Sample 2
This flower is called mountain
pride. It took me forever to find
what this flower was. It is a really
beautiful flower. It is also known
as, “Penstemon newberryi and it is
a bushy perennial subshrub that
reaches a height between 12 to 30
centimeters” (Mathews, L).

19. Plant: Sample 3
This flower, I think, is the
Sulphur flower. This is the
name I found for the closest
resembling flower to this.

20. Plant: Sample 4
This is a sagebush.
“Common Name:
Sagebrush, Big Sagebrush
Genus: Artemisia
Species: tridentata” (K., E).

21. I wasn’t lucky enough to see any animals on the larger scale, or on the small scale
for that matter. I heard the birds, but couldn’t spot where they were. Therefore, I
researched the common animals of the area and they are: “BIRDS: American
Robin, Bald Eagle, California Gull, Canada Goose, Dark-eyed Junco, Hairy
Woodpecker, Mallard, Mountain Chickadee, Red-tailed Hawk, Steller's
Jay, Western Tanager, Yellow-Headed Blackbird. MAMMALS: Black
Bear, Coyote, Douglas Squirrel (Chikaree), Golden-mantled Ground Squirrel, Mule
Deer, Pine Martin, Yellow-bellied Marmot” (The Lake Tahoe Basin).

22. Animal: Sample 1
I believe this butterfly is the
Spring Azure. It is also known as
the Celastrina ladon. “Family:
Lycaenidae; Subfamily:
Polyommatinae” (Butterflies and
Moths of North America).
Unfortunately I couldn’t find any
information on the evolution of
this butterfly.

23. Animal: Sample 2
“The Steller’s jay is a bold and
aggressive species frequently
found scavenging in campgrounds,
picnic areas, and feeding stations
in the West. It’s identification is a
nearly unmistakable dark blue,
black-crested jay with variable
white or blue markings on the
head. The wings and tail are a vivid
blue, with fine black barring. The
head, including the crest; back;
and throat are blackish (Stellar’s
Jays). It is also known as
Cyanocitta stelleri. I couldn’t find
evolution for this either.
(Stellar’s Jay Photo)

24. Animal: Sample 3
The Brown Bear. They are the
most common bear seen in the
area. They are most fun to see
when they are mom and baby,
although, it isn’t safe to get close
to baby even if you don’t see
mom because she is closer than
you think. The brown bear is
also known as Ursus arctos.
Brown bears are thought to
evolve from Ursus etruscus. They
remain from the Pleistocene,
where it is believed that they
outcompeted cave bears.
(brown bear of south lake tahoe)

25. (The Lake Tahoe Basin)

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K., E. (n.d.). Common Sagebrush - Artemisia tridentata. Blue Planet Biomes. Retrieved June 12, 2013, from
http://www.blueplanetbiomes.org/common_sagebrush.htm
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http://www.rockhounds.com/rockshop/rockkey/
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