field presentation lake tahoe
DESCRIPTION
a field presentation of lake tahoe for GEO at LTCCTRANSCRIPT
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.