Lake TahoeA Geological Field Study by Dean Hyland

History● The Tahoe basin

was formed 3 to 4 million years ago due to a series of normal faults (USGS)● The basin dropped

while adjacent blockswere uplifted, resultingin the beautiful basin we have today● Pliocene Epoch (Cenozoic Era)

Recent History● During the ice age,

glaciers formed and created large U-Shaped valleys

● Lateral and Terminal morraines became beautiful lookouts

● Angora Lake, Fallen Leaf, Cascade Lake

Cave Rock

● Cave Rock is a beautifuloutcropping on the westernshore of Lake Tahoe● was once part of the neck

of a volcanic vent that formed 5 million yearsago (S.N Geotourism)● water level was once higher and wave movement formed the

beautiful cave systems● tourism and recreational climbing have started to ruin the site

and it has since then been named sacred and untouchable by the Washoe Tribe (S.N Geotourism)

Lake Clarity Over Time

● Due to road and building developement, the Lake Tahoe area has amassed a great appeal for tourism

● Golfing, Hiking, Lake activities, and casinos

● Lake Clarity has lowered at a rate of roughly 1 foot per year and continues to get worse from pollution (USGS)

Smoky Quartz● Smoky quartz is common

in the Tahoe area● a macrocrystalline variety

of Quartz (SiO2)● the smoky color occurs when

crystalline quartz is exposed to radiation or adjacent to radioactive rocks for long periods of time (Mineral Miners)

● sometimes forms with etched pattern of lines, depressions, or terminations

Granodiorite● cooled slowly and intrusively in plutons● characterized by its salt and

pepper look● found this sample at Van Sickle

State Park● small interlocking

crystals what looks like quartz, muscovite, and some feldspars

● not a pretty rock

Unidentified Sample

● consisting of one solid white feldspar● cooled intrusively and slowly● slightly foliated, with no

noticable pattern● found in Van Sickle

State Park, common

American Black Bear

● found in my front yard eating chocolate cake

● common in residential areas since Angora fires and tourists continue to give the bears food

● this was just a baby, which made me wonder where the mom was

American Black Bear

● Pliocine and Pleistocen eras(Monroe)

● Kingdom-Animalia● Phylum-Chordata● Class-Mammalia● Order-Carnivora● Family-Ursidae● Genus-Ursus● Species-Americanus

Smoothed Granite

● Found on pathway in Van Sickle● well smoothed from weathering● has some micah crystals

but appears to contain mostly feldspar

● bad picture quality

Oxidized Igneous Granite

● created in large plutons● cooled intrusive, slow● oxidized due to iron (Fe)

content● found in Van Sickle State

Park

SourcesGould, M. (2012, December 1). Lake Tahoe Geography Overview. . Retrieved August 1, 2014, from http://tahoe.usgs.gov/geography.htmlNCPC. (2012, May 1). Cave Rock Project. . Retrieved July 28, 2014, from http://www.ncpc.info/projects_caverock.htmlMiners, M. (2014, June 1). Smoky Quartz. . Retrieved July 1, 2014, from http://www.mineralminers.com/html/smqminfo.htmMonroe, J. (2012). The Plezozoic. The Changing Earth (). Brookstone: Coller.