THE SIERRA NEVADA MOUNTAINS

Only the end Of 400 million years of history

Miscellaneous epeiric seas From about 600 my BP

THE THREE SIERRAS ~ 250 – 150 million years = 1 st Sierras ~ 120 – 60 million years = 2 nd Sierras ~ 20 my – present = 3 rd Sierras

1 st SIERRAS

1 ST SIERRAS Timing - ~ 250 – 150 my Part of Pangea Subduction formed Little evidence –Later intrusion and metamorphism –Erosion (twice)

2 nd SIERRAS

2 ND SIERRAS Timing -~ my N.A. separated and moving westward Subduction formed Evidence partially destroyed by erosion

Plate motions and the 2 nd Sierras

40my of erosion to the 2 nd Sierras ~60-20 my no subduction erosion

3 rd SIERRAS

Block faulting to form the 3 rd Sierras ~20 my – eastern part southern block is uplifted; internal faulting at 12 my; ?uplift at ~9 my ~9 my – main block is tilted to west Erosion continued for 20 my but slightly different on the two blocks N

Details about the blocks Details are dependent on datable lavas and pyroclastic material, or on dateable terminal sediments of the Kern River. Not much and not much done!

Erosion on the 3 rd Sierras Streams until the ice ages –Main block – E and W after 9 my tilting –Southern block – S by the Kern River ?60 my to present Valley glaciers off and on 1.6 my to present for the higher parts

Kern River-1 Controlled by ancient fault dating back to 2 nd Sierras Controlled by ancient fault dating back to 2 nd Sierras Fault = Kern Canyon Fault Fault = Kern Canyon Fault Located primarily on Southern block Located primarily on Southern block Timing Timing 60 – 20 my, Mt. Whitney to Kernville to Colorado River 60 – 20 my, Mt. Whitney to Kernville to Colorado River 20 – 12 my, Mt. Whitney to Kernville to Caliente Creek to Bena to San Joaquin Valley 20 – 12 my, Mt. Whitney to Kernville to Caliente Creek to Bena to San Joaquin Valley 12 – present, Mt. Whitney to Kernville to lower Kern River to San Joaquin Valley 12 – present, Mt. Whitney to Kernville to lower Kern River to San Joaquin Valley

Kern River-2 Current topography Current topography

Kern River my my Topography much different Topography much different Empties into Colorado River to E Empties into Colorado River to E

Kern River-4 20 – 12 my 20 – 12 my Topography different Topography different Empties into San Joaquin basin SE of Bakersfield (Bena) Empties into San Joaquin basin SE of Bakersfield (Bena)

Kern River-5 12 – present 12 – present Topography similar Topography similar Empties into San Joaquin basin toward Bakersfield Empties into San Joaquin basin toward Bakersfield

Kern River-6 Ancient Lake Isabella – north Ancient Lake Isabella – north Walker Lake – south Walker Lake – south not on Kern R. not on Kern R ~1 my 12 - ~1 my

ECONOMIC RESOURCES

TOURISM Summer – hiking, backpacking, rock climbing, camping, boating, fishing, sightseeing, (in selected areas) hunting Winter – skiing –Mammoth area –Donner Pass area –Several other smaller areas

GOLD-1 Foothills E of Sacramento

GOLD-2 DEEP HYDROTHERMAL VEINS EXPOSED BY 60+ MY OF EROSION— 1850’s, 1930’s, 1980’s PLACER DEPOSITS BY 60+ MY OF STREAM SORTING AND DEPOSITION— 1850’s, 1930’s

TUNGSTEN DEEP HYDROTHERMAL VEINS EXPOSED BY 60+ MY OF EROSION Hydrothermal fluids + CaCO 3 Primarily WWII

SOUTHERN GEM MINES Tourmaline, beryl, and garnet From the ‘shallow’ pegmatites of San Diego and Riverside counties Varied depending on price for gems—1920’s empress of China bought quantities of tourmaline Fine mineral samples

facetted tourmaline (boron)

Rough beryl (beryllium)

Cut garnets (various)

pegmatite An odd igneous rock It contains concentrations of rare elements and forms rare minerals