Notes:CALIFORNIA GEOLOGY

In terms of land mass, California was the last state to form in the North American tectonic plate / US . . . The Pacific Ocean beach used to be at Nevada! The creature shown represents a fossil that was a marine hunter which has been found in Nevada

1) Plates Converging During the breakup of Pangaea, the Pacific Plate and N. American Plate were converging, and the Pacific Plate subducted under the N. American plate (where the Nevada border is) B. The Sierra Nevada Mountains started to form volcanically!

2) Evidence of volcanism. . . Diorite (granite) is an intrusive, igneous rock that makes up most of the Sierras.

Ocean water, land, pressure, and heat mix underneath the ground . . . Mafic rock from an ocean plate mixed with sea water under heat and pressure will produce a slimy green-looking rock called SERPENTINE. The mineral QUARTZ from granite will generally form within Serpentine beds The mineral GOLD is found in Quartz veins!

The “Mother Lode” area in California was famous for finding Gold!

More about Serpentine and El Dorado Hills. . . Since we are living at the base of the Sierras, we are living around lots of Serpentine! Asbestos (Tremolite) is a naturally occuring mineral that is present in some Serpentine. Asbestos fibers in nature are straight, but synthetic asbestos fibers are curly. Some asbestos can sometimes cause a lung cancer called Mesothelioma ( if someone were to breathe in large amounts for a very very long time) Asbestos is very Heat-resistant and can Be woven into strong materials

. . . There is a rock called “CHERT” which is made from metamorphosed seashells and organic sea material. CHERT is present all over California, but mostly in the Sierra Nevadas and Coastal Ranges(near the old subduction zone). These mountains contain Chert because an Oceanic Plate covered with sea shells, etc. was subducted. Indians used them for arrow heads and flint It has a colorful, waxy appearance “MELTED CRAYONS”

3) Sharp Peaks and Valleys form in the Sierras Glaciers covered the mountains, and carved sharp canyons inside them. Faulting activity from earthquakes created more hills and sunken valleys. . . Lake Tahoe was one of these.

YOSEMITE . . A Living Legend Yosemite National Park was once covered in and shaped by Glaciers and faulting. . . It is one of the most famous and protected national parks.

4) The Central Valley is formed . . . Glaciers, wind, water, and sun slowly decompose parts of the Sierra Nevadas (Weathering) These pieces are also transported by these elements along with gravity to the base of the Mountains (Erosion) These pieces are dropped, pile up and layer at a very fast rate. (Deposition) The Central Valley is now the “beach”.

. . . More on the Central Valley The Central Valley is one of the best agricultural regions in the world, because: It is able to retain and absorb water equally over a large area, because it’s relatively flat. It is accessible to natural watering systems ( melted snow, Delta, mountain watershed)

The Delta: Ocean water coming inland from San Francisco It helps make the Central Valley fertile because of the variety of sediments and organic compounds that it dumps and mixes to create the soil … from mountains, wind, and ocean (Alluvium)

5) The Pacific Plate changes direction . . . We know at one point in history, the Pacific Plate stopped moving into the N. American Plate, and began to move past it in a North-Westerly direction. The Hot Spot under Hawaii (Emperor Sea Mounts) is like A trail of “crumbs” that Can be followed to Verify this change.

6) The Coastal Ranges are Formed . . . As the Pacific Plate moves northward, it “snags” against the North American Plate as it goes by. This causes folding (wrinkling) that you can see, especially around the San Andreas Fault line. These bumps are the Coastal Ranges.

7) The story ends with the California Coast . . . More weathering, erosion, and deposition occurs on/around the coastal ranges, and edge of the Pacific Plate. This creates our Pacific Coastline.

Discussion Questions. . . What is the difference between the Sierra Nevadas, and the Coastal Ranges? How can you tell?

Discussion Questions. . . Glaciers can carve out huge areas of rock over a long time. How could Glaciers have helped to start the California Gold Rush?

Discussion Questions. . . What order was the following formed: Central Valley, Sierras, Coastal Ranges, CA Coastline?