Lake Tahoe's Environment and Ecology

Geology

Lake Tahoe is a masterpiece of nature and most locals can tell you just how it was created. In a nutshell, the Tahoe Basin was formed about five to ten million years ago by the rising and falling of the land due to the shifting of geologic faults.

Tremendous forces began the western tilt of the Sierra Nevada block. As a result, two principal parallel faults developed. The eastern margin created the Carson Range and the western margin created the Sierra Nevada. The up-thrown fault blocks created the highest peaks in the region. The down-thrown fault blocks sank to create a deep v-shaped valley, now called the Lake Tahoe Basin.

Later, about two million years ago, volcanic activity followed and played a key role in further reshaping the landscape of the region. Lava flowing from Mt. Pluto formed a barrier across the Basin's northeastern outlet, creating a natural dam across Lake Tahoe's original outlet, the Truckee River. Water from the snowfall and streams gradually filled the Lake Tahoe Basin, over 600 feet higher than its present lake level! Eventually, a new outlet eroded through the northeastern lava dam, creating the present path of the Lower Truckee River, the only outlet of the lake.

Then an Ice Age developed and huge glaciers grew in the surrounding mountains and gradually moved down the v-shaped canyons on the western side of the lake. The glaciers scoured away loose rock and reshaped the canyons into the broad, u-shaped valleys of Emerald Bay, Fallen Leaf Lake and Cascade Lake.

Today, the highest point in the Tahoe Basin is Freel Peak at 10,881 feet. The deepest part of Lake Tahoe is near Crystal Bay, measuring a water depth of 1,645 feet.

Granite- Peaks & Pieces

The glorius peaks that surround Lake Tahoe are mountains of granite. This light gray, medium to coarse-grained rock is prevalent in the Sierra Nevada Mountains, along with other igneous rocks and metamorphic slate.

Granite is composed of two light-colored minerals, quartz and feldspar. Some granite appears to be salt and pepper in appearance due to the presence of darker colored minerals such as iron and magnesium.

Much of the sandy, sterile soil in most of the region is composed primarily of decomposed granite rock. It is coarse in texture, low in plant nutrients and high in erosion potential. Fortunately, much of the sandy soil in the region is covered by a "duff" of fallen pine tree needles and decomposing natural materials. This natural covering helps cushion and absorb rainfall, thus slowing the speed of natural erosion.

When you visit the Lake Tahoe Basin, it is best to stay on established trails and roads in order to minimize the disturbance of this fragile surface condition.

Flora & Fauna

Trees

Alder, Aspen, Cedar, Jeffrey Pine, Lodgepole Pine, Ponderosa Pine, Sierra Juniper, Sugar Pine, White Fir, Willow.

Wildflowers

Blue & Purple: Dwarf Alpine Aster, Lupine, Meadow Penstemon
Pink & Red: Columbine, Indian Paintbrush, Shooting Star, Snow Plant, Thistle
White: California Corn Lily, Common Yarrow, Cow Parsnip, Mariposa Lily, Ranger Buttons
Yellow: Buttercup, Mountain Mule Ears, Sulphur Flowers

Birds

American Robin, Bald Eagle, California Gull, Canada Goose, Dark-eyed Junco, Hairy Woodpecker, Mallard, Mountain Chickadee, Red-tailed Hawk, Steller's Jay, Western Tanager, Yellow-Headed Blackbird.

Mammals

Black Bear, Coyote, Douglas Squirrel (Chikaree), Golden-mantled Ground Squirrel, Mule Deer, Pine Martin, Yellow-bellied Marmot.