Field assgt.


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Field assgt.

  1. 1. Field AssignmentProfessor Lawler- Geology103By Kalie Ceglia
  2. 2. • Geologic Evolution of Tahoe Basin and the Sierra Nevada• Rock Samples• Quartz• Agate• Granite• Plant Sample- ‘snow plant’• References
  3. 3. Geologic evolution of Lake TahoeBasin(started 400 million years ago)• Lake Tahoe was formed by faulting• 3 faults make up the Tahoe Basin- West Tahoe Fault ( Sierra Nevada), East Tahoe Fault ( Carson Range),and the North Tahoe Fault• ‘Dropped down blocks ‘ formed the Basin in between• Soils include:- Andesitic volcanic rocks- Granodiorite- Metamorphic, 2013
  4. 4. T. Macrae, 2009• The weight of the glaciers cause it to move and flow downhill• This creates U-shaped glacier valleys and V-shaped stream valleys
  5. 5. The glaciers move through canyons like this one
  6. 6. Glacier movement through river beds
  7. 7. More recently:• About 10MYR ago, the real uplift of the Sierra Nevada happened:• Volcanic rock, sedimentary rock, and metamorphic rock were carriedaway to surrounding valleys, as a result there is still geologic evidencein the Tahoe Basin• As recent as 10,000yr ago, the last parts of the Ice age, glaciation washappening in the Sierra Nevada• How the Emerald Bay area was formed is an example of a lateralmoraine( where sediment is transported, then deposited along theridges)Monroe, 357, 2006
  8. 8. Evidence of ScrapingAs the glaciermoves it picksup:• rocks• sediment• boulders• The boulders androcks scrape alongthe bedrock
  9. 9. Approx. 6800ft, Near Eagle FallsTrail
  10. 10. Lake Tahoe and BasinFeatures Metric unit English unitMaximum depth(second deepest in the U.S.)501 m 1,645 ftAverage depth 305 m 1,000 ftMaximum diameter(north-south)35 km 22 miMinimum diameter(east-west)19 km 12 miSurface area 495 km2 191 mi2Average surface elevation(above sea level)1,897 m 6,225 ftHighest peak (Freel Peak) 3,320 m 10,891,2013
  11. 11. Topographical map of Emerald,2013
  12. 12. The Glaciers Taking ShapeGlaciers:• Glaciers are very large bodies of snow and ice combined• When more snow accumulates than can melt, glaciers are formed• The snow begins to melt in the day but refreezes at night , this formsthe singular sheet of iceResendes, 2011
  13. 13., 2013Lower Eagle FallsLocation: South Lake Tahoe, Lake Tahoe Basin,El Dorado CountyStream: Eagle CreekAlternate Names:Height: 140 ft.Elevation: 6600 ft. (-350 ft.)Lat/Long:38.95185, -120.11029
  14. 14.,2013Topographical of Upper Eagle Falls and Eagle Falls LakeLocation: South Lake Tahoe,Lake Tahoe Basin,Eldorado CountyHeight: ~20 ft.Elevation: 660 ft.Lat/Long:38.94999N,120.11618W
  15. 15. Lower Eagle Falls • During the Spring the snowmelts rush down from above,come mid-summer,it is only a trickle• Due to the number ofvisitors, there is anincreasing environmentalconcern for theEagle Falls area
  16. 16. Standing on top of the Lower Eagle FallsFannette Island:This island is made of Granite, which resisted the force of the glacial ice.
  17. 17. Upper Eagle FallsLocation: South Lake Tahoe,Lake Tahoe Basin,Eldorado CountyHeight: ~20 ft.Elevation: 6650 ft.Lat/Long: 38.94999N, 120.11618W
  19. 19. Quartz found locally in the Lake TahoeBasinRockshop,2013
  20. 20. Quartz: mineral•Form the continental crust•Most commonly clear, white (milky), or rose incolor•It is considered a hard and stable mineral•In metamorphic rock, it can become veineousand banded in, 2013
  21. 21. • Veins of quartz canprovide evidence ofhydrothermal, 2013
  22. 22. Agate:Semi-precious silicamineral• Microcrystalline variety ofsilica• Associated with and foundaround volcanic rocks orwhere volcanic activityonce occurred• Comes in a variety ofshapes and colors• Appears banded when cut
  23. 23. More Agate( This was found in the middle of the trail and was the onlyother specimen than the picture before during the whole hike)
  24. 24. GraniteGranite: The Sierra Nevada wasvolcanically active. Not a surpriseto find granite which wasat one time magma
  25. 25. Granite: igneous rock, silicate• Granular• Intrusive• Varies in color: pink, white, gray, red• Mineral content: biotite, quartz, mica, orthoclase feldspar• Granite is part of the continental crust• It is magma from deep in the crust , cooled down and formed intorock then pushed up to the Earth’s surface
  27. 27. Scientificname: SarcodessanguineaRank: SpeciesHigherclassification: SarcodesSarcodesSarcodes is a monotypic genus of a single springtime floweringplant in the heath family containing the single species Sarcodes sanguincommonly called the snow plant or snow flower.Wikipedia, 2013Found in the Sierra Nevada
  28. 28. ReferencesBackyard Nature with Jim Conrad. (n.d.). Retrieved fromhttp://www.backyardnature.netEagle Falls Trail Lake Tahoe. (n.d.). Retrieved April 3, 2013, from Bay SP. (n.d.). Retrieved 2013, from about Lake Tahoe. (n.d.). Retrieved from Image Result for (n.d.). Retrieved June 16, 2013, from
  29. 29. Granite: Igneous Rock - Pictures, Definition & More. (n.d.).Retrieved from, B. (1998). Glaciers of California: Modern glaciers, ice ageglaciers, origin of Yosemite Valley, and a glacier tour in the SierraNevada. Berkeley: University of California Press.Hill, M. (1975). Geology of the Sierra Nevada. Berkeley: Universityof California Press.Lake Tahoe Facts, Natural History, & Human Histroy. (n.d.).Retrieved June from, T. (n.d.). Born of glaciers | Beetles In The Bush.Retrieved April 5, 2013, from
  30. 30. Monroe, J. S., & Wicander, R. (2006). The changing Earth:Exploring geology and evolution. Belmont, CA: ThomsonBrooks/Cole.Resendes (2011). Plate tectonics: Continental drift and mountainbuilding. Berlin: Springer-Verlag.Sarcodes - Wikipedia, the free encyclopedia. (n.d.).Retrieved May 15, 2013, from Map of the Eagle Falls Trail, Lake Tahoe, California.(n.d.). Retrieved from, the free encyclopedia. (n.d.). Retrieved June 18, 2013,from