The document summarizes a field/lab project conducted by Brisa Ramirez in the fall of 2010. They collected rock samples from a hillside located near the San Joaquin fault in California. The samples included quartz rocks, sandstone, basalt rocks, gabbro, a quartz pebble, and brown quartzite. Pictures and descriptions of the samples are provided. Additional pictures show the San Joaquin fault line, examples of weathering and erosion, different sedimentary environments, and structures like a bridge and dam that demonstrate practical applications of geology.

1. Field/Lab Project
Fall 2010
By: Brisa Ramirez
Field/Lab Assignment
Pt. 1
Location
Icollected my rock samples from a
dry grassy hillside off the base of a
mountain.
 The mountain hillside is located just
off the West Side freeway also
known as the I-5 which runs parallel
to the San Joaquin fault.
More on the location...

2. -Looking at the picture to the left we can see how
after being carried down hill these gravel sized
rocks were deposited into medium sized pot
holes.
-The picture to the right shows how the dirt on
this hill has a light almost grey appearance. This
could indicate high sodium content.
Location Continued…
Just off the mountain side runs the West Side
freeway. Here we see a practical use of Geology
in both the highway and the bridge. The bridge
was built over the depression between these two
hills.
Geological
Background
 Thesemountains began to form
about 30 million years ago.
 Therewere no visible rock
formations above ground.

3.  Some of the types of rocks I found
in this area included quartz,
basaltic, sandstone and grabbo.
Location Concluded
 There are some obvious signs
of erosion taking place due to
rain water
 Between the hills are crevice
like depressions where there is
a large deposit of rocks and
gravel
 The hills are all covered in
grass and very few rocks can

4. be seen from a distance
 Most rocks are between the
size of pea and baseball
 There are also a few rocks the
range from the size of a small
cantaloupe to a large
watermelon
Rock Samples
 Here is a picture of all the rock
samples I collected from off of the
hillside.
I was able to collect samples from
all three rock types (igneous,
metamorphic and sedimentary).
Rock Identification

5. Process
 Theinternet was the primary
source which I used in order to
indentify the samples I collected.
 Main internet source:
http://saltthesandbox.org/rocks/qu
artzrock.htm
Iused my Geology book as a
secondary resource for information
during the identification process.
Rock Identification
Process Cont…
 Duringthe identification process I
used vinegar and a nail in order to

6. help classify my samples.
 Vinegar produces a chemical
reaction with certain minerals found
in some rocks.
Iused the nail in order to test my
samples by scratching them.
Quartz Rocks
Iconcluded that these rocks are of
igneous origin.
Iwas unable to determine the exact
rock type of these samples.
 However, they all seem to contain
quartz.
 Therefore I classified them as being

7. quartz rocks.
Quartz Rocks
 As you can see these rocks
appear to contain more than
one type of rock
 However I will focus on the
quartz in these samples
 Quartz is white in color and
does not bubble when placed
in acid or scratch when rubbed
with a nail
 These rocks are layered
showing that different minerals
were deposited to form the
different rocks composed in
each sample
Wacke: Sandstone

8.  Sandstone comes from a
sedimentary origin.
I came to the conclusion this rock
was a “wacke” sandstone rock
because it better resembled the
sandstone type rocks.
 Its rough exterior played a major
role in the identification process for
me.
Wacke: Sandstone
 Sand stone has a rough texture
 It has a light brownish color
with dark grey specks
 On the bottom there is a faded

9. orange or rust like color

 Sandstone is quite durable
Basalt Rocks
 Basalt is also an igneous type rock.
 I concluded that these might be
basaltic rocks because of their dark
color and dull look.
 Also, basaltic rocks do not produce
bubbles in vinegar nor did scratch
with the nail.
 These rocks passes both tests.
Basalt Rocks
 These rocks all have a dark
grayish color

10.  The surface of these rocks is
smooth until broken
 When broken the edges are
jagged and semi sharp
 These rocks appear to have
small cracks in them
Gabbro
 Shown here is another igneous rock,
Gabbro.
I came to the conclusion that this
rock most resembled a gabbro type
rock because of the way the surface
shined in the sunlight (not really
visible under this lamp).
 Gabbro rocks contain small crystals
at the surface that shine in the
sunlight.

11. Gabbro
 This rock is grey and has black,
brownish and off white
speckles in it
 Rough to the touch
 Does not scratch when rubbed
with a nail
Quartz Pebble
 Here we have another igneous type
rock.
I concluded that this little white
rock is a quartz pebble.
I came to this conclusion because of
it obvious white look.

12. Quartz Pebble
 This pebble is white with a
little brownish and black color
at two ends
 Does not bubble when placed
in acid
 Will not scratch when rubbed
with a nail
 This pebble is only about three
eights in diameter
Brown Quartzite
 Quartzite is a metamorphic type
rock.

13.  After much evaluation I concluded
that these two are brown quartzite
rocks.
I believe the larger rock better
resembles the description of brown
quartzite.
Brown Quartzite
 Both of these rocks have a light
brownish color to them
 Smooth to the touch
 The larger rock has some
quartz still imbedded in it
 Have a little shine to them like
a glassy finish

14. Field/Lab Assignment
Pt. 2
The San Joaquin Fault
 Here are two pictures I took of the San
Joaquin Fault
 The fault line is where the base of these two
rows of hills meet
San Joaquin Fault
Cont…
 The San Joaquin fault is located
in the San Joaquin valley west
of the I-5 freeway.
 The fault runs parallel to the
I-5.
 In order to get to the fault

15. location I had to park off the
freeway and walk several miles
over the hills in order to find it
and take pictures.
 This fault is a transform fault.
 The San Joaquin Fault is said to
be a seismically active.
Weathering
 Here is an example of mechanical
weathering.
 This picture is of the Mendota
aqueduct.
 In this picture we can clearly see
how the cement barrier is being

16. broken down.
 Thishappened over a process of
time as the water seeped into
cracks, froze eventually breaking
the cement into smaller and smaller
pieces.
Weathering Cont…
 Here
is another example of the
mechanical weathering process.
 This
picture is from the Mendota
dam.
 Here we can see the deterioration
of the cement block.
 Eventually
the deterioration of this
cement block will lead to a flood

17. because as it weakens it wont be
able to hold back the water.
Mass Wasting
 In
this picture we find a good
example of mass wasting.
 All
the rocks that are now near the
bottom were once located at the
very top.
 Over
time these rocks were pulled
down by the force of gravity.
Erosion
 This
is a picture of two rocks found
near the base of the dam.
 Aswater flows over these rocks,
they are slowly being broken down
by sediment the water carries with

18. it.
Erosion Cont…
 Asyou can see this is some of the
sediment and broken rocks that
have settled near the shore line of
the dam.
 Youmay notice how all the rocks
here are smooth. This is because as
the water carries them they are
slowly sanded smooth.
Sedimentary
Environments
 This
picture shows a continental
sedimentary environment. It was
taken on an environmental reserve.

19.  Wecan see here how the dirt
contains many small pebbles.
 Alsothe dirt is a light white color
do to the build up of salt, which
keeps plants from growing.
Sedimentary
Environments
 This
is an example of a marine
sedimentary environment.
 As you can see the larger rocks are
found deeper in the water where as
the smaller rocks are found closer
to the shore.

20. Sedimentary
Environments
 Lastly, wehave an example of a
transitional sedimentary
environment.
 In
this picture the rocks are not
sorted by size, this is because the
water has receded therefore the
shoreline is much lower than
normal.
 Thistransitional environment is part
of the San Joaquin River.
Practical Use of
Geology
 This bridge (Skaggs Bridge) is

21. located above the San Joaquin
River.
 In
examining this bridge we see a
practical use of geology.
 Asyou can see this bridge goes
over the original much larger river
bed.
 This
bridge is made of cement
which is a man made rock.
 Because of this bridge people are
able to safely cross the San Joaquin
River and commute to other cities
and towns.
Practical Use of
Geology

22.  This
is a picture of the Mendota
dam.
 Thispicture also exemplifies a good
use of geology.
 This
dam holds back the water
belonging to the Mendota Slough.