field assgt
TRANSCRIPT
Emerald Bay, Eagle Falls and
the Sierra Nevada
Field Assignment Professor Lawler- Geology
103By Kalie Ceglia
Contents:
• Geologic Evolution of Tahoe Basin and the Sierra Nevada• Rock Samples
• Quartz• Agate• Granite
• Plant Sample- ‘snow plant’• References
Geologic evolution of Lake Tahoe Basin (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 rock
Tahoefacts.com, 2013
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
The glaciers move through canyons like this one
Glacier movement through river beds
More recently:
• About 10MYR ago, the real uplift of the Sierra Nevada happened:
• Volcanic rock, sedimentary rock, and metamorphic rock were carried away to surrounding valleys, as a result there is still geologic evidence in the Tahoe Basin
• As recent as 10,000yr ago, the last parts of the Ice age, glaciation was happening in the Sierra Nevada
• How the Emerald Bay area was formed is an example of a lateral moraine( where sediment is transported, then deposited along the ridges)
Monroe, 357, 2006
Evidence of Scraping
As the glaciermoves it picks up:• rocks• sediment• boulders
• The boulders androcks scrape alongthe bedrock
Approx. 6800ft, Near Eagle Falls Trail
Lake Tahoe and Basin
Features Metric unit English unit
Maximum depth(second deepest in the U.S.)
501 m 1,645 ft
Average depth 305 m 1,000 ftMaximum diameter(north-south)
35 km 22 mi
Minimum diameter(east-west)
19 km 12 mi
Surface area 495 km2 191 mi2
Average surface elevation(above sea level)
1,897 m 6,225 ft
Highest peak (Freel Peak) 3,320 m 10,891 ft
Tahoe.usgs.gov,2013
Topographical map of Emerald Bay
Americansouthwest.net,2013
The Glaciers Taking Shape
Glaciers:
• 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 forms the singular sheet of ice
Resendes, 2011
Tahoebest.com, 2013
Lower 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
Americansouthwest.net,2013
Topographical of Upper Eagle Falls and Eagle Falls Lake
Location: South Lake Tahoe, Lake Tahoe Basin, Eldorado County Height: ~20 ft. Elevation: 660 ft. Lat/Long: 38.94999N,120.11618W
Lower Eagle Falls • During the Spring the snow melts rush down from above, come mid-summer, it is only a trickle
• Due to the number of visitors, there is an increasing environmental concern for the Eagle Falls area
Standing on top of the Lower Eagle Falls
Fannette Island:
This island is made of Granite, which resisted the force of the glacial ice.
Upper Eagle Falls
Location: South Lake Tahoe, Lake Tahoe Basin, Eldorado County Height: ~20 ft. Elevation: 6650 ft. Lat/Long: 38.94999N, 120.11618W
UPPER EAGLE FALLS
(TAKEN FROM THE BRIDGE LOOKING DOWNSTREAM)
Quartz found locally in the Lake Tahoe Basin
Rockshop,2013
Quartz: mineral
•Form the continental crust•Most commonly clear, white (milky), or rose in color
• It is considered a hard and stable mineral• In metamorphic rock, it can become veineous and banded in appearance
www.backyardnature.net, 2013
• Veins of quartz can provide evidence ofhydrothermal activity
Geology.com, 2013
Agate: Semi-precious silica mineral
• Microcrystalline variety of silica
• Associated with and found around volcanic rocks or where volcanic activity once occurred
• Comes in a variety of shapes and colors
• Appears banded when cut
More Agate
( This was found in the middle of the trail and was the only other specimen than the picture before during the whole hike)
GraniteGranite: The Sierra Nevada was volcanically active. Not a surprise to find granite which was at one time magma
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 into
rock then pushed up to the Earth’s surface
SARCODES OR ‘SNOWPLANT’
Scientific name: Sarcodes sanguineaRank: SpeciesHigher classification: Sarcodes
SarcodesSarcodes is a monotypic genus of a single springtime flowering plant in the heath family containing the single species Sarcodes sanguinea, commonly called the snow plant or snow flower.
Wikipedia, 2013
Found in the Sierra Nevada
ReferencesBackyard Nature with Jim Conrad. (n.d.). Retrieved from http://www.backyardnature.netEagle Falls Trail Lake Tahoe. (n.d.). Retrieved April 3, 2013, from http://www.tahoesbest.com/eagle-falls-trail-lake-tahoeEmerald Bay SP. (n.d.). Retrieved 2013, from http://www.parks.ca.gov/?page_id=506Facts about Lake Tahoe. (n.d.). Retrieved from http://tahoe.usgs.gov/facts.htmlGoogle Image Result for http://www.aboutlaketahoe.com/hiking/topo-maps/emerald-bay-topo.jpg. (n.d.). Retrieved June 16, 2013, from http://www.google.com/imgres?imgurl=http://www.aboutlaketahoe.com/hiking/topo-maps/emerald-bay-topo.jpg&imgrefurl=http://www.aboutlaketahoe.com/hiking/emerald_bay
Granite: Igneous Rock - Pictures, Definition & More. (n.d.). Retrieved from http://geology.com/rocks/granite.shtmlGuyton, B. (1998). Glaciers of California: Modern glaciers, ice age glaciers, origin of Yosemite Valley, and a glacier tour in the Sierra Nevada. Berkeley: University of California Press.Hill, M. (1975). Geology of the Sierra Nevada. Berkeley: University of California Press.Lake Tahoe Facts, Natural History, & Human Histroy. (n.d.). Retrieved June from http://www.tahoeadventuresports.com/misc/tahoefacts.htmMacrae, T. (n.d.). Born of glaciers | Beetles In The Bush. Retrieved April 5, 2013, from http://beetlesinthebush.wordpress.com/2009/03/17/born-of-glaciers/
Monroe, J. S., & Wicander, R. (2006). The changing Earth: Exploring geology and evolution. Belmont, CA: Thomson Brooks/Cole.Resendes (2011). Plate tectonics: Continental drift and mountain building. Berlin: Springer-Verlag.Sarcodes - Wikipedia, the free encyclopedia. (n.d.). Retrieved May 15, 2013, from http://en.wikipedia.org/wiki/SarcodesTopographic Map of the Eagle Falls Trail, Lake Tahoe, California. (n.d.). Retrieved from http://www.americansouthwest.net/california/lake_tahoe/eagle-falls-trail-map.htmlWikipedia, the free encyclopedia. (n.d.). Retrieved June 18, 2013, from http://en.wikipedia.org/