Fallen Leaf Lake Field Assignment

Riley Chestnut

Content

Fallen Leaf Geological Background Geological Features Snow Plant History Mallard (Anas Platyrhincos) History Metamorphic Rock Igneous Rock

Fallen Leaf Geological Background

• Similar ecosystem to the rest of the basin

• Formed during the Pleistocene glaciation

• Glaciers left behind polished granite rocks

• The Fallen Leaf moraines were formed by the large Tahoe glacial episode, 70,000 to 150,000 years ago

•Watersheld covers an area of about 42 square km• Trees consist of common Jeffrey, Ponderosa and Lodgepole pines, also some non native quaking aspens in the area

Geological Features

Terminal Moraine- accumulation of ridge-like rock debris, pushed forward by glacial activity

Lateral Moraine- debris derived by erosion and avalanche from the valley wall onto the edge of a glacier and depositing as an elongated ridge

Medial Moraine- formed by two glaciers from the east and west

Geological Features

• Fallen leaf Moraines– Angora and Cathedral ridge

• Medial moraines– Strip of land between Lake

Tahoe and Fallen Leaf• Two terminal moraines

– North end of lake is shallow and south end marks the terminal moraines with a sharp drop off

– Two moraines suggests the glacier retreated more than once

Snow Plant History Sarcodes sanguinea

• Occurs through out Sierra Nevadas, Southern Oregon, Western Nevada and Northern Mexico

• Non-photosynthetic and receives all nutrients from fungal root symbionts

• Receives all carbon from fir host tree through mycorrhizal

• Suggests algal ancestor with similar symbiotic, mineral absorbing fungus

Mallard HistoryAnas playtrhincos

• Ancestors to wild ducks thought to have appeared during the time of the dinosaurs – Pliocene or early

Pleistocene epoch– About 2 mya, in

present day Siberia

Mallard History Anas playtrhincos

• Ancestors to all domesticated ducks– Hybridize with about

45 other species of ducks and are thought to destroy the mallard species completely if continued

Metamorphic Rock

• Marposa Slate – Fine grained, foliated metamorphic rock– Formed when pre-existing rocks are

subject to extreme heat and/or pressure– Composed of clay minerals or micas

Metamorphic Rock

• Formation of Slate– Created in formally sedimentary basin that

becomes involved in a convergent boundary

– Forces and heat modify clay minerals– Foliation develops at right angles to the

compressive forces to yield vertical foliation

Igneous Rock

• Quartz Monzonite Granite– Dominant igneous rock

found in the basin– Light colored, granular and

course-grained• Made up of quartz,

plagioclase feldspar, potassium feldspar

– Lesser amounts of biotite, hornblend and other minerals

Granite formations nearby at Angora Lake

Igneous Rock

• Formation of granite– Minerals crystallized

from magma, cooled deep below earths crust

• Three-six miles deep– Magma cooled

slowly, allowing large crystals to form

Bibliography

"Rocks of the Sierra Nevada." Geology of the Sierra Nevada.

Geologic Trips, n.d. Web. 20 June 2013.

<http://www.geologictrips.com/sn/sntro.pdf>.

King, Hobart. "Slate." Metamorphic Rock. Geology.com, n.d. Web. 20 June

2013. <http://geology.com/rocks/slate.shtml>.

Alden, Andrew. "Granite." Granite and Its Geology. About.com Geology,

n.d. Web. 20 June 2013.

<http://geology.about.com/od/rocks/ig/igrockindex/rocpicgranite.htm>