THE SIERRA NEVADA MOUNTAINS

1. THE SIERRA NEVADA MOUNTAINS

2. Only the end • Of 400 million years of history

4. Miscellaneous epeiric seas • From about 600 my BP

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

6. 1st SIERRAS

7. 1ST SIERRAS • Timing - ~ 250 – 150 my • Part of Pangea • Subduction formed • Little evidence • Later intrusion and metamorphism • Erosion (twice)

8. 2nd SIERRAS

9. 2ND SIERRAS • Timing -~ 120-60 my • N.A. separated and moving westward • Subduction formed • Evidence partially destroyed by erosion

10. Plate motions and the 2nd Sierras

11. 40my of erosion to the 2nd Sierras • ~60-20 my • no subduction • erosion

12. 3rd SIERRAS

13. Block faulting to formthe 3rd 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

14. 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!

16. Erosion on the 3rd 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

17. Kern River-1 • Controlled by ancient fault dating back to 2nd Sierras • Fault = Kern Canyon Fault • Located primarily on Southern block • Timing • 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 • 12 – present, Mt. Whitney to Kernville to lower Kern River to San Joaquin Valley

18. Kern River-2 • Current topography

19. Kern River-3 • 60 -20 my • Topography much different • Empties into Colorado River to E

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

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

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

23. ECONOMIC RESOURCES

24. 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

25. GOLD-1 • Foothills E of Sacramento

26. 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

27. TUNGSTEN • DEEP HYDROTHERMAL VEINS EXPOSED BY 60+ MY OF EROSION • Hydrothermal fluids + CaCO3 • Primarily WWII

28. 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

29. facetted tourmaline (boron)

30. Rough beryl (beryllium)

31. Cut garnets (various)

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