The document discusses various rocks, geological formations, and wildlife found near the Yuba River in the Tahoe National Forest. Samples of quartzite, basalt, and granite rocks were collected and identified based on their characteristics. An angular unconformity sample showed tilted igneous rock overlaid by sedimentary deposits. An inclusion sample showed an older lighter rock within a darker surrounding rock. Other observations included a blackberry bush, signs of brown bears, and details about the formation of the Yuba River over millions of years.

1. Field Assignment
in the Tahoe
National Forest
By, Frank KouzelMartinez

2. Quartzite This quartzite was found near the Yuba river.
Quartz gold mining started in Grass Valley back
in the mid 1800’s, so it’s not surprising to find
remnants of quartzite all along the Yuba river;
close to Grass Valley. Quartzite is made of
quartz –rich sandstone that was compressed
together by a reaction to heat, pressure, and a
chemical activity of metamorphism.
This sample was eroded by the nearby river
smoothing out much of it, but the texture of
parts was rough and the color and crystalline
structure made me believe it was quartzite. It’s
color variation, medium hardness, decent
brittleness, and coarseness also led me to
believe it was quartzite.
(Quartzite, 2016)

3. Basalt
Basalt is one of the most common types of
rock found. It is extrusive, dark or mafic,
and smooth grained. These are the
characteristics I found in this sample by
the Yuba river. Basalt usually contains
magnesium, pyroxene, and plagioclase
minerals. This rock seemed to be smoother
when rubbed with friction against other but
was still decently hard.
(The Changing Earth,2012)

4. Granite
Granite is very is a very popular find in the
Sierras, and the Yuba river has a ton of
rocks of granite everywhere! Granite is
made of mainly quartz and feldspar with
minor amounts of mica, amphiboles, and
other minerals. Granite is an intrusive
igneous rock that is coarse and light in
color much like this sample. Granite is a
sialic rock meaning it is high in silica. This
granite likely contains quartz and feldspar.
The rock was very hard making me believe
it was granitite as well.
(The Changing Earth,2012)

5. Angular
Unconformity
Angular unconformity occur after
strata has been tilted or fold and
then since eroded. This sample I
found near the Yuba River
appears to have been tilted then
near the top an erosional layer
appears with sedimentary
deposits on top of the tilted
igneous rock.
(The Changing Earth, 2012)

6. Principle of Inclusions
The principle of inclusions states that
inclusions or fragments of rocks within
another rock are older than the rock it is
included within. In this case the lighter rock
is an inclusion within the darker rock
surrounding it. That would mean the lighter
rock is older than the rock surrounding.
This particular inclusion appears to be two
types of igneous rocks.
(The Changing Earth, 2012)

7. Blackberry Bush
This berry bush was found in an area where
there’s not any other berry bush around. It could
have gotten there by the types of animals that
cross this area around the Yuba river. When
animals find these fruits or berries to eat, they
are involuntarily spreading the seeds as they
are carrying them around. Over time, berries
have evolved to be much bigger than they used
to be. This is because humans have used
selective breeding in order to just plant the
seeds of berries from bushes that produced the
best berries. Berries are a gymnosperm or
flowering plant. They evolved from plants that
used spores to spread genetic material and
acquis plants. Today gymnosperms such as this
berry plant are the dominant type on the
continents. They have the pollen and seeds
spread by animals like birds, bees, and
humans.
(The Changing Earth, 2012)

8. Brown Bear
A brown bear evolved from its oldest
relative, the Ursavus. The Ursavus was
more or less as big as a sheepdog, and
had evolved from a canine ancestor.
But before this ancestor bears can trace
their roots Therapsids the first mammal
reptiles. From the therapsids split into
plancental eutherians, egg laying
monotremes and pouch bearing
marsupials. Bears fall under eutherians.
Brown bears originally came from
Canada, the northwest end of the
United States (Alaska, Washington,
Montana, Idaho, and Wyoming), and
across northern Europe and Asia. They
must of slowly worked their way into
different states like California.
(The Evolution of Bear Species, 2016)

9. Middle Yuba River
The Yuba River has four tributaries, which are
Downie River, Goodyears Creek, Canyon
Creek, and Slate Creek. These four creeks and
rivers are what created the Yuba River. The
Yuba River is one of the main rivers that
provides the Feather River about one-third of
it’s flow. The Yuba river first began as trickle of
water carving its way out of the sierra
mountains millions of years ago from higher in
the mountains as a tributary of the feather river.
The river has since been damned multiple times
flooding and changing the landscape further
such as at Bullards Bar Reservoir near
Camptonville, Ca.
(Geology and Geomorphology, 2016)

10. References
Geology and Geomorphology. (n.d.). Retrieved June 23, 2016, from
http://www.northforktrails.com/RussellTowle/NorthFork/Geology/Geology.ht
ml
Quartzite. (n.d.). Retrieved June 23, 2016, from
https://www.mineralseducationcoalition.org/minerals/quartzite
The evolution of bear species. (n.d.). Retrieved June 23,
2016, from http://www.bearsinmind.org/Page/The-
evolution-of-bear-species
Monroe, J. S., & Wicander, R. (2012). The changing Earth exploring geology and evolution. Belmont, CA:
Thomson Brooks/Cole.