Background and Research Methodology In early July I visited the surrounding areas above Lake Tahoe. The photos and rock samples included in this report are from this field trip that I took with my husband and dogs.
The Lake is the third deepest lake in North America. It is 12 miles wide and 22 miles across. If you stand on one shore you can see the curvature of the earth looking to the other end and will be unable to see the other shore. The depth of the lake is approximately 1,600 feet. The elevation is 6500 feet at lake level. Photo taken in from Eagle Falls of Emerald Bay.
Black Bears are common in the region. The American black bear dates to before the Late Pleistocene. They are found from Canada to Mexico.
Sierra wildflowers are colorful and abundant. Sierra Larkspur are commonly seen. Their formal name is Delphinium. Delphinium is a genus of about 300 species of perennial flowering plants in the family Ranunculaceae, native throughout the Northern Hemisphere and also on the high mountains of tropical Africa. All members of the Delphinium genus are toxic to humans and livestock.
Plants of the Tahoe basin; Flowering plants, trees, and ferns (First ed., pp. 72-73). Sacramento, Ca. California Native Plant Society Press.
Gilmore Lake in California is a backcountry lake in the Sierra Nevada mountain range, to the west of Lake Tahoe in the Desolation Wilderness. It can be reached by hiking west out of the Glen Alpine Springs trailhead near the town of South Lake Tahoe. Sierra Nevada is a tilted fault block about 420 miles long, with a rugged terrain, and sloping west face.
West side has metamorphic rock formed by plate tectonics in Early Paleozoic to Late Jurrasic.
Spooner Lake to the East is surrounded by grass and meadow when water levels fall you can see more of the swampy meadow as here in this photo.
Metamorphic rocks changed that were changed from heat and pressure or chemical activity
I think the rock found here is Phyllite is mainly made up of quartz and fine grained mica. Phyllite is an intermediate grade. It comes from the metamorphism of shale.
Identification of rocks done using: Geology of the Sierra Nevada, by Mary Hill (2006)
Quartz is an abundant mineral. It is also an important rock forming mineral. As much as 12% of the earth is made up of quartz. It is a very stable mineral, more than others. Quartz is often found along the trails in and around Lake Tahoe.
About 30 million years ago, an era of volcanism of massive proportions began in the sierras. During this era, the sierra began uplifting again to form many parallel faults. The area to the west rose while the area to the east dropped. This is now Carson Valley. The Tahoe Basin, like Carson Valley, has dropped between two uplifted blocks; the Sierra Crest on the west and the Carson Range on the east. This helped form the lakes in the Sierra Nevada. Volcanic activity occurred frequently just north of the lake, and a lava flow eventually crossed over the Carson River. This dammed the valley and formed Lake Tahoe.
Glaciers in the Pleistocene helped form the lakes and canyons of the Sierra Nevada.
Lake Tahoe Basin Mgt. Unit Learning Center. Retrieved August 1, 2014 from http://www.fs.usda.gov/detail/ltbmu/learning/
About 25 million years ago the Sierra Nevada formed by what is known as faulting. Glaciers formed the lake and surrounding canyons. Mount Pluto formed a dam from lava flow which water and snow melt formed a much larger lake than what we know today.
Granite is a common rock found all over the Sierra Nevada and Granite is also the most abundant rock of the continental crust. Granite forms in plutonic environments and contains potassium feldspar, plagioclase feldspar, quartz, biotype and amphibole. Granite is igneous rock with coarse grain classification.
