Rock Formations

San Diego has said to be one of the most active regions in the United States. The San Andreas Fault in San Diego has a very rare tectonic plate activity. The whole process of tectonic plates colliding and producing subduction, creates the magma that comes up and erupts from the Volcano. Lava erupting from the volcanoes and flowing down to land affects the kinds of rocks that are on the earth's surface.

This picture shows the lava flowing down on the surface and the magma that is deep in the Earth's crust.

There are three general types of rocks, igneous, sedimentary and metamorphic. Metamorphic rocks are formed when they are exposed to heat or pressure that causes a physical or chemical change in them. Sedimentary rocks are formed when the process of weathering and erosion happens, in a physical/chemical process. Igneous rocks are formed when they come in contact with lava and can be formed either above or underground.

 

This picture is of the Rock Cycle which is the process of rocks being created, changed, destroyed and then created again.

Centuries ago, lava that erupted from the Volcanoes of the Ring of Fire along the Pacific Coast, had caused many igneous rocks to form. The lava caused some extrusive igneous rocks to form, but, it had also allowed some rocks to stay under the surface and cool. The magma going under the Earth's surface cools slower, creating intrusive igneous rocks like sills or dykes.

This image shows where the different intrusive igneous rocks that are formed. It also shows where the extrusive igneous rocks can be formed by the ash and lava.

 However, throughout the years, because of The San Andrea’s weathering and erosion, the intrusive igneous rocks became metamorphosed sedimentary rocks. The plates constantly colliding and building friction, added pressure and heat to the intrusive igneous rocks transforming them to sedimentary rocks.

This map shows the outlining of the Peninsular range

Sedimentary rocks can be seen on these tide pools in San Diego.

            These sedimentary rocks was then pushed up onto huge mountain groups called the Peninsular Range Mountain, which are the part of the San Diego County Mountains. These group of mountains are covered in sedimentary rocks and run north south along the Pacific Coast. Even though the Peninsular Range Mountains stretch along the coast, the Core part of the mountains lie in the San Diego County.

This is the Cuyumaca Mountains in San Diego, which is part of the Peninsular Range Mountains and can get up to 40 inches of rainfall in the upper regions. 

Sources:
"GEOLOGIC CONDITIONS." 3.4 GEOLOGIC CONDITIONS (n.d.): 3.4-.4-10.Sandiego.gov. Draft General Plan, Sept. 2007. Web. 13 Oct. 2014.
Lubowe, Joan. "San Diego Geology." San Diego Hotels. San Diego. Sunbelt Publications, 28 Dec. 2004. Web. 13 Oct. 2014.
"SAVE OUR FOREST AND RANCHLANDS." SAVE OUR FOREST AND RANCHLANDS (n.d.): n. pag. Peninsular Range Wilderness Eco-System. SOFAR. Web. 13 Oct. 2014.
Tauxe, Lisa. "ES10 - EARTH." Igneous Rocks. The Blue Planet, n.d. Web. 14 Oct. 2014.