California General Geology and Landforms

  1. California has more than 800 different geologic units that provide a variety of rock types, mineral resources,geologic structures and spectacular scenery.
  2. Both the highest and lowest elevations in the 48 contiguous states are in California, only 80 miles apart. The tallest mountain peak is Mt. Whitney at 14,496 feet; the lowest elevation in California and North America is in Death Valley at 282 feet below sea level.
  3. California’s state mineral is gold. The Gold Rush of 1849 caused an influx of settlers and led to California becoming the 31st state in 1850.
  4. California’s state rock is serpentine. It is apple-green to black in color and is often mottled with light and dark colors, similar to a snake. It is a metamorphic rock typically derived from iron- and magnesium-rich igneous rocks from the Earth’s mantle (the layer below the Earth’s crust). It is sometimes associated with fault zones and often has a greasy or silky luster and a soapy feel.
  5. California’s state fossil is the saber-toothed cat. In California, the most abundant fossils of the saber-toothed cat are found at the La Brea Tar Pits in Los Angeles.
  6. California state gem, benitoite, was discovered in 1907 in San Benito County. Crystals are typically light to sapphire blue, but can also form in a wide range of colors. Although benitoite is found in several places worldwide, large gem quality crystals are found only in California.
  7. The Mendocino Triple Junction is located off the coast of northern California, where three tectonic plates (Pacific Plate, Gorda Plate, and North American Plate) meet.
  8. The San Andreas Fault forms a transform plate boundary where the Pacific Plate meets the North American Plate south of the Mendocino Triple Junction.
  9. Geologic hazards in California can consist of earthquake shaking and fault movement, tsunamis, landslides, volcanic eruptions, floods, and exposure to hazardous minerals.
  10. Floods in California occur along the flood plains of streams and rivers, and also in desert washes and alluvial fans. Alluvial fans form at the mouths of canyons in California’s deserts and semi-arid environments from floodwaters depositing sediment as the water velocity decreases.
  11. The Salton Sea was created in 1905 when several floods inundated a bypass in irrigation canals and diverted the entire Colorado River for nearly two years. Currently, the Salton Sea is maintained by water diversions from the Colorado River.
  12. Salts are found throughout California’s desert areas in basins that have periodically filled with water that subsequently dried up or evaporated. Evaporation of freshwater in Mono Lake, thought to be the oldest lake on the North American Continent, has left behind salts and minerals making the water three times saltier than sea water.
  13. During the ice ages 15,000 years ago, Death Valley contained a lake more than 100 miles long and 600 feet deep.
  14. Marine terraces along California’s coastline represent former sea level surfaces and can be used to measure upli?? rates. A 125,000 year old marine terrace found in many of California’s coastal areas represents the last ?? me global sea level was high. Twenty-five marine terraces can be found on San Clemente Island, dating back as far as approximately 2.8 million years.
  15. Fossils of mammoths, dogs, bears, cats, horses, camels, antelope, bison, sheep, turtles, shellfish, flamingos and palm trees have been found in sedimentary rocks in southern California near Barstow. A variety of other fossils such as oysters, snails, clams and vertebrates have also been found in northern California.

California Geomorphic Provinces and Geology

  1. California is divided into 11 geomorphic provinces: : Basin and Range, Cascades, Coast Ranges, Colorado Desert, Great Valley, Klamath Mountains, Modoc Plateau, Mojave Desert, Peninsular Ranges, Sierra Nevada, and Transverse Ranges.
  2. The geology and landforms of California were largely created by three episodes of subduction of the oceanic plate under the continental plate from the west, the initiation and growth of the San Andreas fault system, and the extension of the Earth’s crust in the Basin and Range area.
  3. The Sierra Nevada and the Coast Ranges provinces were formed from the collision of tectonic plates, while the Basin and Range and Mojave Desert provinces were formed from the extension of the crust.
  4. 19. The Salton Trough region of the Colorado Desert province is currently spreading, or undergoing extensional ringing, similar to the plate motion that created Baja California.
  5. Racetrack Playa, in the Basin and Range province, (Death Valley) has grooves etched into the surface of the playa by “moving” rocks that are found at the end of the grooves. It is thought these grooves are formed by rocks entrained in ice being blown across the playa by strong winds.
  6. Pillow basalts, like those found in the Coast Ranges, were formed when molten lava cooled under the ocean in shapes resembling the size and shape of a pillow.
  7. Portions of old oceanic crust, called ophiolites, are visible today in the Coast Ranges, the Klamath Mountains, and in the Sierra Nevada.
  8. Chert is a type of rock in the oceanic crust that formed from silica shells of microscopic organisms deposited on the deep ocean floor. Chert is present throughout California, but especially in the Coast Ranges and the Sierra Nevada.
  9. Two blocks of granite c rock, known as the Salinian Block of the Coast Ranges, more closely resemble rocks of the Sierra Nevada rather than most of the rocks making up most of the Coast Ranges. One block lies between the Nacimiento and San Andreas Fault Zones in the southern Coast Ranges and west of the San Andreas Fault in the northern Coast Ranges, suggesting large displacement along the San Andreas and Nacimiento Faults.