This document provides information about Fallen Leaf Lake in a geology report. It summarizes the geological formation of the lake, noting that it was formed by glacial moraines. It describes some of the local plant and animal life, including manzanita plants, Jeffrey pine trees, Lahontan cutthroat trout, and dark-eyed juncos. It also mentions the various rock formations found in the area, such as granite, basalt, and phyllite. Finally, it provides some brief facts about Fallen Leaf Lake, such as its dimensions and historical winter snowfall amounts.

1. Fallen Leaf
Lake
Rochelle Miller
Professor Lawler
Geology 103
Spring 2014
Photo by author

2. Content
• Geological summary
• Map and location
• Plant examples
• Native animals
• Rocks and landscape
• Fallen Leaf Lake facts

3. Geological Summary
-Fallen Leaf Lake was formed by glacial moraines.
-The east and west sides of the three-mile-long
lake are bounded by lateral moraines and the
lake is separated from Lake Tahoe by a series of
recessional moraines.
-Fallen Leaf Lake is 150 feet above Lake Tahoe and
drains into Lake
Tahoe through Taylor Creek, which cuts through
these recessional moraines.
-If there were no lateral and recessional moraines,
there would be no Fallen Leaf Lake.
(http://www.geologictrips.com/sn/snttlt.pdf)
Photo by author

4. • The south end of Fallen Leaf Lake lies at the base of one of the
large faults along which the Tahoe block was downfaulted several
thousand feet.
• The lake sits in a pile of glacial debris that was carried down the
scarp of this fault by Pleistocene glaciers.
• This glacial debris fills in much of the southern part of the Tahoe
basin.
• As the lake was filled in, the glaciers rode over the older glacial
material and continued to dump their debris into the lake.
(http://www.geologictrips.com/sn/snttlt.pdf)

5. http://www.fishsniffer.com/locations/lakes/fallen-leaf-lake/

6. Manzanita plant
(Arctostaphylos species)
(http://www.laspilitas.com/gro
upsmanzanita_arctostaphylos/
Manzanita.htmlhttp://).
The genus evolution was
likely centered in the far
western part of North
America, where fossil
ancestors dating to the
Middle Miocene are
apparent. The genus was
likely even more diversified
as it evolved into the Early
Tertiary. Evolution of genus
Arctostaphylos likely shares a
similar timeline with that of
Ceanothus, which is another
western North America
genus that exhibits fire
regenerative properties.
Extensive use of the fruit
and leaves were made by
prehistoric peoples for
culinary, medicinal and
ceremonial purposes.
Photo by
author

7. Jeffrey Pine (Pinus jeffreyi)
Photo credit-
http://www.laspilitas.com/plants/fragrant.htm

8. • Jeffrey pine (Pinus jeffreyi) was discovered in 1852 in the Shasta Valley of
California by John Jeffrey, a Scottish botanical explorer. Partly overlapping
ponderosa pine (Pinus ponderosa) in range and superficially resembling it,
Jeffrey pine was first classified as a variety of ponderosa pine (28,45). These
western yellow pines produce wood of identical structure and quality and are
closely related taxonomically (10). Jeffrey pine is distinct chemically,
ecologically, and physiologically and is readily distinguished from ponderosa
pine on the basis of bark, leader, needle, bud, and cone morphology (23).
• The Jeffrey pine may live 400 to 500 years and can attain immense size. It
typically grows to 4 to 6 feet in diameter, and 170 to 200 feet in height. To
date, the largest Jeffrey pine recorded in the western Sierra Nevada had a
diameter of 7.5 feet, and a height of 175 feet.
• Jeffrey pine is found primarily in California extending north through the
Klamath Mountains into southwestern Oregon, across the Sierra Nevada into
western Nevada, and south to the Transverse and Peninsular Ranges and into
northern Baja California. In the northeast, central, and southern portions of its
range, climate and elevation determine its distribution, rather than soil type.
(http://eol.org/pages/999712/details).

9. • Lahontan Cutthroat Trout
• Historically, only a few species of fish lived in Lake Tahoe. The
Lahontan Cutthroat Trout was the dominant fish. Large and long-
lived, it grew to an impressive 50 inches in length and weighed 40
pounds. Native people throughout the Great Basin depended on
the trout for their livelihood.
• However, the Lahontan cutthroat’s fate changed dramatically during
the 19th and 20th centuries. The fish were caught in high numbers
to sustain the towns and mining camps of the growing West. Dams
and development destroyed habitat. By 1970, the fish were listed as
an endangered species. In 1975, that classification was lowered to
“threatened.”
• Extensive efforts are underway to restore the Lahontan cutthroat to
its traditional range.
(http://keeptahoeblue.org/abouttahoe/animals-plants/)

10. Dark-eyed Junco
Photo credit-
http://blog.nwf.org/2011/01/bird-
of-the-week-dark-eyed-junco/
Photo by author
Among the most variable of all North American birds, the dark-eyed junco features several
distinct color forms, five of which were once considered separate species. Today six groups of
subspecies—or types—of a single species, Junco hyemalis, are accepted by ornithologists. The
two most widespread are the “slate-colored junco” of the eastern United States and most of
Canada and the “Oregon junco,” which inhabits much of the West.
(http://blog.nwf.org/2011/01/bird-of-the-week-dark-eyed-junco/).

11. Photo by author
Igneous rock-
Granite
Granite rock is the
result of magma or
lava crystallizing
As it cools, the
resulting rock is
characterized by
interlocking mineral
grains.
Magma that cools
beneath the surface
produces intrusive
igneous rocks such
as Granite (Monroe,
Wicander 17).Felsic - "light" rocks, contain light colored minerals
(Also low temp minerals See Bowen's Below)
(quartz, Potassium feldspar, micas). (http://www.dinojim.com/
Geology/GeoBasics/igneous.html#Types

12. Basalt rock- extrusive Igneous
Photo by author
Extrusive igneous rocks cool at the surface unlike intrusive igneous rocks. Both igneous
rocks are formed when magma or lava crystallizes (Monroe, Wicander 17).

13. Phyllite-Metamorphic rock
Photo by author
Metamorphic grade is a term that generally characterizes the degree to which
a rock has undergone a metamorphic change.
Photo by author
Phyllite is a foliate metamorphic rock that is made up mainly of very
fine-grained mica. The surface of phyllite is typically lustrous and
sometimes wrinkled. It is intermediate in grade between slate and schist
(http://geology.com/rocks/phyllite.shtml).

14. Fallen Leaf Lake Facts
• Fallen leaf is 3 miles wide, 1 mile long,
and 400 feet deep.
• In the winter of 1951-52, Fallen Leaf got
over 12 feet of snow!
• 4000 years ago, Washoe Indians used
Fallen Leaf for summer camp.
(Courtesy of Tahoe Heritage Foundation)

15. References
"Geologic Trips." . N.p., n.d. Web. 22 June 2014. <http://www.geologictrips.com/sn/snttlt.pdf>.
Hogan, C. "The Encyclopedia of Earth." . N.p., 12 June 2012. Web. 22 June 2014.
<http://www.eoearth.org/view/article/150218/>.
"A voice for lake Tahoe." . N.p., n.d. Web. 22 June 2014. <http://www.trpa.org/wp-content/uploads/Tree-ID-
tip-sheets_2012-version-MS.pdf>.
Jenkison, James . "Encycopedia of Life." . N.p., n.d. Web. 22 June 2014. <http://eol.org/pages/999712/details>.
Tangley, Laura. "Bird of the Week: Dark-eyed Junco." Wildlife Promise Bird of the Week Darkeyed Junco
Comments. Wildlife Promise, 31 Jan. 2011. Web. 22 June 2014. <http://blog.nwf.org/2011/01/bird-of-the-
week-dark-eyed-junco/>.
Lehame, Jim . "Dinojim.com - Geology Stage 1.4: Igneous Rocks." Dinojim.com - Geology Stage 1.4: Igneous
Rocks. N.p., n.d. Web. 22 June 2014. <http://www.dinojim.com/Geology/GeoBasics/igneous.html#Types>.
"Phyllite." : Metamorphic Rock. N.p., n.d. Web. 22 June 2014. <http://geology.com/rocks/phyllite.shtml>.
Monroe, James S., and Reed Wicander. The changing earth: exploring geology and evolution. 6th ed. Belmont,
CA: Brooks/Cole, 2001. Print.
Wilson, Bert. "Manzanitas of California, (Arctostaphylos species)." . N.p., 11 Dec. 2013. Web. 22 June 2014.
<http://www.laspilitas.com/groupsmanzanita_arctostaphylos/Manzanita.htmlhttp://).>.