The document summarizes information about the Sierra Nevada mountain range, Lake Tahoe, and various plants and rocks found in the area. It describes how the mountains formed from the shifting of tectonic plates over 130 million years ago. It also discusses Lake Tahoe's sources of water, the mallard duck, Jeffrey pine tree, different types of igneous rocks including granite and basalt, and how conglomerate rocks can form near streams. Photos were provided by Crystal Brown and Angelee Brown to accompany the text.

1. South Lake Tahoe
A field study
By Crystal Brown

2. Sierra Nevada Mountain Range
Until about 130 million years ago, the place that the Sierra Nevada mountains now sit was completely
covered by an ocean (Ride).
Plate tectonics began to shift and the Pacific Plate dropped under the North American Plate. During
the Paleozoic era, the pressure and friction caused the crust to melt and liquid plutonic rock to float
towards the surface. This rock hardened to form the granite that makes up much of the rock these
mountains consist of today.
The crash of the two plates also caused enough force to uplift the land. This formed the mountains
that we now know as the
Sierra Nevada Mountain Range
(Ride).

3. Lake Tahoe’s Water Sources
Lake Tahoe has many different water sources. Lake Tahoe is so clear due to
the fact that 40% of it’s water comes directly from rain and snow fall (Ride).
Also, the water that comes from streams goes through a natural filtration
system. The streams go through meadows and marshes. This process
removes much of the dirt and prevents it from reaching the lake.
The lake only has one river outlet
called the Truckee River and
keeps its level mostly through
evaporation (Ride).
However, lack of rain or snow has
caused the lakes level to visibly
drop at times as well.
*These pictures are from Eagle
Falls

4. Mallard Duck
The mallard duck is very common and can be found
in almost any wetland environment. They have adapted enough to be
found in various places around the world (“All”).
The mallard duck is the ancestor of nearly all domestic duck breeds.
Because of this, they have evolved into several different looks and may
be difficult to identify.
They have changed and evolved enough over time to have created
completely different species of ducks. For example, the Mexican Duck
is closely related to them although they are considered a different
species (“All”).

5. Jeffrey Pine
The Jeffrey Pine is closely related to , and at first mistaken for,
the Ponderosa Pine. However, this tree has learned to
adapt to harsh climates unlike the Ponderosa (Jenkinson).
The Jeffrey Pine has evolved to be able to withstand harsh winters
and infertile sites. It can survive through droughts and cold winters.
The reason for it’s unique ability to adapt to multiple conditions
and environments is due to it’s shorter growing season than
other trees (Jenkinson).
This trees ability to adapt to the cold winters and hot,
dry summers of Lake Tahoe makes this tree one of the
most common in the basin.

6. Granite
Igneous Rock
The most common rocks of the Sierra Nevada Mountains is
Granite, a type of igneous rock (“Rocks”).
This rock formed from slow cooling magma when the basin
was created.
It is identified by it’s grains that are visible to the naked eye.
It is composed mainly of quartz and
feldspar as well as minor amounts
of other minerals (“Rocks”).
They occur underneath the Earth’s
crust and take a long time to form
from the slow cooling process.

7. Granite
with xenoliths
An xenolith is a rock fragment that becomes trapped in
another rock while it is newly forming and cooling (Jones).
These pictures show gabbroic (closely related to basalt)
xenoliths that are enclosed inside
granite rock (Jones).
This means that the granite rock
around the xenolith is younger
than the gabbroic xenolith itself.

8. Basalt
Igneous Rock
Basalt is another rock of the igneous rock type.
This rock is formed from lava that cooled quickly and is
usually black or dark in color.
Basalt is the most common type of rock found under the
Earth’s surface.
Basalt is fine grained.
If weathered, the rock can turn a
lighter color. If broken open however,
the inside would be darker than it’s
surface. The picture on the right shows
the blacker areas that have not been
weathered yet (“Rocks”).

9. Conglomerate – Forming
Environment
Around the river of Eagle Falls there are many small pebbles. They mainly seemed
to consist of broken off granite, quartz, basalt, and sandstone (“Rocks”).
This environment is a prime
spot for conglomerate to
develop.
If these pebbles are buried and
lithified, these rocks may become part of a
conglomerate, or sedimentary type, rock (“Rocks”).

10. Works Cited
 “All about Birds.” The Cornell Lab ofOrnithology. http://www.allaboutbirds.org/gui
 de/mallard/lifehistory
 “Rocks”. Geology.com. http://geology.com/rocks/granite.shtml
 Jenkinson, James L. “Jeffrey Pine” Encyclopedia of Life. http://eol.org/pages/999
 712/detailsLife
 Jones, Noris W. “The Sierra Nevada Batholith.” Department of Geology. http://www
du/~cejones/GeoImages/3IntrusiveBodies/1Plutonsz/2SierraNevadaCloseUps.html
 Ride, Sally. EarthKam. “The Sierra Nevada Mountains and Lake Tahoe” https://earth
kam.ucsd.edu/ek-images/investigating_images/lake_tahoe
Photos taken by Crystal Brown/Angelee Brown