FIELD LAB ASSINGMENTBy: Francisco Rosas Manzo

Physical Geology: Spring 2011

PART 1

Rocks

Background Information

The area I chose to collect my samples from was in the Sierra Nevada at Kings Canyon National Park. The most common types of rocks in Kings Canyon National Park are “granitic” rocks. These include granite and other black and white speckled rocks similar in composition to granite. Most of the Sierra Nevada is made of these igneous rocks that formed from magma cooling and hardening deep inside the earth. Other kinds of rocks that can be found throughout the park are mostly metamorphic rocks such as marble, schist, slate, and quartzite. The metamorphic rocks formed from sedimentary and volcanic rocks that underwent heat and pressure.

I did my best to try and identify my rock samples by using our text book and the websites that were made available under the course documents link. I had a hard time trying to identify them because when I was looking for them I thought a lot of them looked the same to me!

Granite This rock I found outside the

visitor center of Kings Canyon National Park. Granite is the best known of all igneous rocks. Granite is coarse-grained rock composed of about 25 percent quartz and about 65 percent feldspar, mostly potassium and sodium rich varieties. Granite is a very abundant rock but it has become very common among geologists to apply the term granite to just about any coarse-grained intrusive rock composed predominantly of light silicate minerals.

Basalt

This rock I found on my way down from Kings Canyon National Park. It was on the side of the road. Basalt is a very dark green to black, aphaenitic rock composed primarily of pyroxene and calcium-rich plagioclase feldspar, with lesser amounts of olivine and amphibole. Basalt is the most common extrusive igneous rock.

Sandstone

This rock I found in a garden of a gas station on the way up to Kings Canyon. The gas station was in Squaw Valley which is a little city in the foothills of the Sierra Nevada. Sandstone is the name given to rocks in which sand-size grains predominate. After shale, sandstone is the most abundant sedimentary rock.

Conglomerate

This rock I found next to a private lake that is located right before you get to the Kings Canyon National Park. Conglomerate consists primarily of gravels. These particles can range in size from large boulders to particles as small as garden peas. Gravels accumulate in a variety of environments and usually indicate the existence of steep slopes or very turbulent currents. Conglomerate is a sedimentary rock.

Weathered Sandstone

This is sandstone that appears to be weathered. I originally thought it was Jasper because, Jasper consists of red tones that are due to the iron oxide it contains and its also a sedimentary rock.

Rocks Conclusion

In the end, I enjoyed searching for the rocks and I actually took a lot of pictures but ended up identifying only these ones because I had a hard time with the identification process. Especially since I only had pictures to go by when identifying them and no actual samples since I did not bring any with me and also because I would second doubt my self a lot when identifying them, so that made it even worse!

PART 2

Fault Weathering Mass Wasting and Erosional Event Sedimentary Environments:

Continental, Marine, and Transitional Practical use of Geology

Fault “A fault is a break in a rock mass

along which movement has occurred.”

The San Andreas is the primary fault of a complex fault network that cuts through rocks of the California coastal region. The entire San Andreas fault system is more than 800 miles long and extends to depths of at least 10 miles within the Earth..

The San Andres Fault consists of two moving plates which are the Pacific Plate which is located on the west and moves northwestward relative to the North American Plate which is on the east, therefore causing earthquakes along the fault. This picture is from right outside the little city of Parkfield, CA the “Earthquake Capital.”

Weathering:

“Weathering is the disintegration and composition of rock at or near the surface of Earth.”

The following picture I took on my way up to Kings Canyon National Park. It is an example of Chemical Weathering. “Chemical Weathering involves a chemical transformation of rock into one or more new compounds.” “Water is the most important agent of chemical weathering.” These rocks have chemical weathering from the water.

Mass Wasting:

“Mass wasting is the downslope movement of rock, regolith, and soil under the direct influence of gravity.” This is a picture of a rock sliding area on the way up to Kings Canyon National Park

Erosional Event:

“Erosion is the physical removal of material by mobile agents such as water, wind or ice.” The following photo is an example of soil erosion that has caused this tree to fall. “Soil may be eroded due to the action of water (runoff) or wind.” This image is of an edge of the San Joaquin River that runs through the Skaggs Bridge County park.

Sedimentary Environments:

“An environment of deposition or sedimentary environment is simply a geographic setting where sediment is accumulating.” “Sedimentary environments are commonly placed into one of three categories: Continental, Marine, or Transitional.”

Continental Environment

: “Continental environments are dominated by the erosion and disposition associated with streams.” The following pictures are of the San Joaquin River at Skaggs Bridge County Park.

Marine environment: “Marine depositional environments

are divided according to depth. The shallow marine environment reaches to depths of about 200 meters and extends from the shore to the outer edge of the continental shelf. The deep marine environment lies seaward of the continental shelf in waters deeper than 200 meters.” “Coral reefs are associated with warm, shallow marine environments.”

A Coral Reef is an example of a marine environment. The first picture is of a Coral Reef display at the California Academy of Sciences in San Francisco. The one next to it is a picture I took of the city of San Francisco while on a boat ride.

Transitional Environment:

“The shoreline is the transition zone between marine and continental environments. Here we find the familiar deposits of sand or gravel called beaches.” This picture is of me and my family on the shoreline of Monterey California.

Practical use of Geology:

This bridge over the San Joaquin River is an example of a practical use of Geology. I drive over this bridge everyday on my way to school.

Sources

1. “Earth: An Introduction to Physical Geology,” Tenth edition. By, Tarbuck, Lutgens, and Tasa.

2. “The San Andreas Fault” By Sandra S. Schulz and Robert E. Wallace http://pubs.usgs.gov/gip/earthq3/safaultgip.html