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Eaton Canyon Field Assignment Jasmine Matevosyan Geol 103

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Page 1: Field presentation

Eaton CanyonField Assignment

Jasmine MatevosyanGeol 103

Page 2: Field presentation

Part 1

Page 3: Field presentation

San Gabriel Mountains

Eaton Canyon is a beautiful park located in Northern Pasadena, a quiet city in the San Gabriel Valley and part of Los Angeles county. Eaton Canyon is a small section of the San Gabriel mountains that attracts hiker and classrooms for field observations. According to their official website, these “young mountains and have been uplifted from their surroundings by faulting, or earthquake movements.” Although these mountains were formed from earthquake activity, that and heavy rain fall are causing shattered rock formed mountains to rapidly erode. The plate activity and movement along the San Gabriel fault continues to create changes to the mountains and overall region.

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Plants

Cacti

The plants are limited to cactuses and other desert area plants the river bed and surrounding area are dry. However, it has nice variety of different plants.

It has an abundance of Prickly Pear Cacti and dry shrub plants

This is due the warm and dry climate that allows them to flourish

Eaton Canyon’s official website gives information on the 58 different types of cacti, shrubs, and other plants

Page 5: Field presentation

Wildlife Due to the heat, the animal sightings were limited. The only animals I observed in around the hiking trails were lizards, rats and birds. However, when I called the nature center to check if the park was open, (the Santa Clarita mountains are burning and the smoke is blowing towards Pasadena) I was told to watch out for coyotes and snakes.

This tiny chubby brown bird is a Bewick’s wren. These birds prefer living around shrubby vegetation is very common in Eaton Canyon (National Geographic).

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Part two

Formation of the San Gabriel Mountains Common rocks found in Eaton Canyon

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Rock types

The San Gabriel mountains and Eaton Canyon are on the San Gabriel fault line

This fault was once a major part of the San Andres fault

Due to earthquakes, the mountain range and all its characteristics around Eaton Canyon formed

It is abundant with igneous and metamorphic rocks

Eaton Canyon provides a rock garden with a bit of information on the rocks at the opening of the park. It contains igneous and metamorphic rocks. The nature center also has a rock gallery so that visitors could go in and learn about the rock formation and history of the San Gabriel mountains.

Page 8: Field presentation

Gneiss

This first rock was found a metamorphic rock that the opening of the park right before the hiking trail. These rocks are created when heat and pressure cause physical, chemical, or both changes to a pre-existing rock (Monroe & Wincander, 2015). This photograph shows obvious changes in the rock with its light and dark layers.

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Biotite Mica Schist

This is another type of metamorphic rocks commonly found in Eaton Canyon.

The patterns seen on the pattern make it recognizable as a metamorphic rock

Its physical appearance shows that pressure was used in the formation of this rock

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Granite Pegmatite

Rocks that have a crystallized structure to them are likely to be igneous rock

Igneous rock is formed from cooling and crystallization of magma or lava or the consolidation of pyroclastic material (Monroe & Wincander, 2015).

These rocks are easily identifiable by their pink color

According to Eaton Canyon’s official website, The pinkish color is due to its potassium content.

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Part 3

Relative dating principles and laws (Law of Super Position, Law of Original

Horizontality, Principle of Inclusions, Principle of Lateral Continuity, Principle of Fossil Succession, etc.

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Law of super position

This image shows the apparent metamorphic rock and pressure from earthquakes forming the rocks

According to the law of super position, the layers at the bottom are older than the layers on top (Monroe & Wincander, 2015).

Different earthquakes putting pressure on the rocks due to the San Gabriel fault create older layers at the bottom

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Nonconformities

The Eaton Canyon portion of the San Gabriel mountain shows several signs of nonconformities

The mountain is falling around and eroding due to heavy rain fall and earthquakes

The erosion can be seen in the surface of metamorphic and igneous rocks

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References

Monroe, J. S. & Wicander, R. (2015). The Changing Earth: Exploring geology and Evolution 7th ed. Stamford, CT: Cengage learning.

National Geographic. (n.d.). Bewick's Wrens, Bewick's Wren Pictures, Bewick's Wren Facts - National Geographic. Retrieved July 25, 2016, from http://animals.nationalgeographic.com/animals/birding/bewicks-wren/

Eaton Canyon Nature Center Associates Home Page. (n.d.). Retrieved July 25, 2016, from http://www.ecnca.org/index.html