field assgt

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/