The document summarizes Kalie Ceglia's geology field assignment at Lake Tahoe, which involved studying the geologic evolution of the Tahoe Basin, collecting rock and plant samples, and taking photos of glacial features. Key findings include: the Basin was formed by faulting 400 million years ago; samples collected included quartz, agate, granite, and a snow plant; photos documented evidence of glacial scraping and movement in locations like Emerald Bay and Eagle Falls.

1. Field Assignment
Professor Lawler- Geology
103
By Kalie Ceglia

2. • Geologic Evolution of Tahoe Basin and the Sierra Nevada
• Rock Samples
• Quartz
• Agate
• Granite
• Plant Sample- ‘snow plant’
• References

3. 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

4. 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

5. The glaciers move through canyons like this one

6. Glacier movement through river beds

7. 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

8. Evidence of Scraping
As the glacier
moves it picks
up:
• rocks
• sediment
• boulders
• The boulders and
rocks scrape along
the bedrock

9. Approx. 6800ft, Near Eagle Falls
Trail

10. 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 ft
Maximum 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

11. Topographical map of Emerald Bay
Americansouthwest.net,2013

12. 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

13. Tahoebest.com, 2013
Lower Eagle Falls
Location: South Lake Tahoe, Lake Tahoe Basin,
El Dorado County
Stream: Eagle Creek
Alternate Names:
Height: 140 ft.
Elevation: 6600 ft. (-350 ft.)
Lat/Long:38.95185, -120.11029

14. 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

15. 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

16. Standing on top of the Lower Eagle Falls
Fannette Island:
This island is made of Granite, which resisted the force of the glacial ice.

17. Upper Eagle Falls
Location: South Lake Tahoe,
Lake Tahoe Basin,
Eldorado County
Height: ~20 ft.
Elevation: 6650 ft.
Lat/Long: 38.94999N, 120.11618W

18. UPPER EAGLE FALLS
(TAKEN FROM
THE BRIDGE
LOOKING
DOWNSTREAM)

19. Quartz found locally in the Lake Tahoe
Basin
Rockshop,2013

20. 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

21. • Veins of quartz can
provide evidence of
hydrothermal activity
Geology.com, 2013

22. 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

23. 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)

24. Granite
Granite: The Sierra Nevada was
volcanically active. Not a surprise
to find granite which was
at one time magma

25. 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

26. SARCODES OR
‘SNOWPLANT’

27. Scientific
name: Sarcodes
sanguinea
Rank: Species
Higher
classification: Sarcodes
Sarcodes
Sarcodes is a monotypic genus of a single springtime flowering
plant in the heath family containing the single species Sarcodes sanguin
commonly called the snow plant or snow flower.
Wikipedia, 2013
Found in the Sierra Nevada

28. References
Backyard Nature with Jim Conrad. (n.d.). Retrieved from
http://www.backyardnature.net
Eagle Falls Trail Lake Tahoe. (n.d.). Retrieved April 3, 2013, from
http://www.tahoesbest.com/eagle-falls-trail-lake-tahoe
Emerald Bay SP. (n.d.). Retrieved 2013, from
http://www.parks.ca.gov/?page_id=506
Facts about Lake Tahoe. (n.d.). Retrieved from
http://tahoe.usgs.gov/facts.html
Google 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

29. Granite: Igneous Rock - Pictures, Definition & More. (n.d.).
Retrieved from http://geology.com/rocks/granite.shtml
Guyton, 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.htm
Macrae, 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/

30. 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/Sarcodes
Topographic Map of the Eagle Falls Trail, Lake Tahoe, California.
(n.d.). Retrieved from
http://www.americansouthwest.net/california/lake_tahoe/eagle-falls-
trail-map.html
Wikipedia, the free encyclopedia. (n.d.). Retrieved June 18, 2013,
from http://en.wikipedia.org/