Geology of Lake Tahoe By Jennifer Kline

Lake Tahoe Community College 2012 Research Presentation,Geology 103

Satellite Pictures, NASA

○ Observations

○ Lake Tahoe Basin Formation

○ Lake Tahoe Faults

○ Rocks found in Lake Tahoe Basin

○ Fauna of the Lake Tahoe Basin

○ Crawfish Fossil Records

○ Lake Tahoe's Ecosystem

○ Flora of the Lake Tahoe Basin

○ References

Table of Content

July 2012 I hiked to Granite Lake in Desolation Wilderness on the South end of the Lake Tahoe Basin.I observed many types of birds including, Bald Eagle, Woodpeckers,Styler Jays, Robins, and a Humming Bird.I also saw a freshwater crawfish and a marmot.

Observation

○ Basin was under a shallow sea on Pangea

○ North American Continental Plate broke off from Pangea (210 mya)

○ Pacific Ocean Plate drifted east○ Pacific Plate was pushed under

North America Plate.○ during the next 130 million years

plate tectonic pressure and magma chamber caused uplift creating the Sierra Nevada Mountain Range

Lake Tahoe Basin FormationSierra Nevadas

○ uplifting formed parallel faults○ Sierra Crest rose in the west○ Carson Range dropped in the east ○ lava flow dammed the Carson

Valley and the Basin was formed○ glaciers carved and polished rock ○ snow run off eventually filled Lake

Tahoe

(Investigating The Sierra Nevada Mountains and Lake Tahoe, (NASA)

Lake Tahoe Basin Formation(continued)

Lake Tahoe Major Faults

Northern portion of Tahoe is tectonically active with three major faults:

● Incline Fault● Stateline Fault● West Tahoe Fault

Picture (Sacramento Bee, 2006)

Igneous intrusive rocks (typically granodiorite) and igneous extrusiverocks (typically andesitic lahar). Small amounts of metamorphic rock occur in the Spooner Summit andDesolation Wilderness areas (NRCS 2007).

Rocks found in Lake Tahoe Basin

Granite formed from increased pressure and temperature from the colliding plates caused rock to melt then the cooling process allowed crystals to form and create the granitic rock seen in the Sierra Nevada.

Rocks found in Lake Tahoe Basin

Granite forms in plutonic environments and contains potassium feldspar, plagioclase feldspar, quartz, biotite and/or amphiboleIgneous rock with coarse grain classification acid

Granite

Metamorphic rock forms when heat, pressure and/or chemical activity transform rock such as sedimentary or igneous rock.Metamorphic rock is much harder than the original sedimentary rock and can still be seen today in many areas as caps on top of the Sierra granitic rock.

Rocks found in Lake Tahoe Basin

Metamorphic Rock Metamorphic rock is an igneous rock containing minerals such as olivines, pyroxenes, amphiboles, micas,feldspars and quartz.

Crayfish,(also called crawfish or crawdads)were introduced into the Lake Tahoe Basin's ecosystem in the 1960s

○ members of Astacidae and Parastacidae families

○ freshwater crustaceans○ evolved from Decapoda order○ lives in freshwater shallows in Lake

Tahoe, surrounding rivers and streams○ feeds on aquatic plants and animal life

Fauna of Lake Tahoe Basin

○ Crawfish evolve from the Decapoda order○ oldest fossil record are the Albian fossils found

in Victoria, Australia

Scientific classificationKingdom: AnimaliaPhylum: ArthropodaSubphylum: CrustaceaClass: MalacostracaOrder: DecapodaInfraorder:AstacideaSuperfamily: ParastacoideaFamily: Parastacidae

(Rodney A. Feldmann, Carrie E. Schweitzer & John Leahy 2011)

Crawfish Fossil Records

Lake Tahoe Basin Ecosystems

All elements must find a way to coexist in the same environment to keep Lake Tahoe's Ecosystem health.

○ soil○ incects○ wildlife○ plants

○ trees ○ water○ people

Elements of Tahoe's Ecosystem

Flora of Lake Tahoe Basin

Kingdom: Plantae Order: FabalesFamily: Fabales Subfamily: FaboideseTribe: Genisteae Genus: Lupinus

Lupinus perennis grows all over the basin and flowers in the spring blooms lasting into the summer. There are about 280 species of this genus.

WEBSITE:Lake Tahoe, From Wikipedia, the free encyclopedia, last update 2012 http://en.wikipedia.org/wiki/Lake_Tahoe#Geology NASA Investigating The Sierra Nevada Mountains and Lake Tahoe, 2012https://earthkam.ucsd.edu/ek-images/investigating_images/lake_tahoe U.S.Geological Survey, Lake Tahoe, 2004http://tahoe.usgs.gov/pictures.html The Sacramento Bee, Lake Tahoe Fault Could Deliver Massive Earthquake, 2006 http://www.standeyo.com/NEWS/06_Earth_Changes/061226.Lake.Tahoe.Fault.html United States Department of Agriculture, Forest Service, Lake Tahoe Basin Management Unit, 2012 United States Department of Agriculture, Natural Resources Conservation Services, 2007

Rodney A. Feldmann, Carrie E. Schweitzer & John Leahy (2011). "New Eocene crayfish from the McAbee Beds in British Columbia: First record of Parastacoidea in the Northern Hemisphere

Reference