Читать книгу Top Trails: Lake Tahoe. Must-Do Hikes for Everyone онлайн

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Though a regional ice sheet was absent, in theory the last ice age put the finishing touches on the Tahoe Basin. Separate rivers of ice followed some of the existing V-shaped stream channels, carving them into classic U-shaped canyons. Glacial action scoured several of the canyons on the west side of the basin, uncovering the classic granite bedrock associated with the Sierra Nevada today. In the process, some of the area’s most picturesque lakes were formed, including Donner, Cascade, Fallen Leaf, and Echo Lakes, as well as scenic Emerald Bay on Tahoe’s southwest shore. Because the Sierra Crest creates a rain shadow effect, which limits the amount of precipitation, minimal glaciation occurred from the Carson Range to the east. Without the glacial scouring on the west side of the Tahoe Basin, the topography of the Carson Range is primarily volcanic soils rather than the classic Sierra granite bedrock. While the west side of the Tahoe Basin is sprinkled with an abundance of tarns, lakes, and ponds, the east side is nearly devoid of such features. Additional glacial activity influenced the area when ice dams formed across the Truckee River canyon and broke several times, producing floods that further shaped the canyon, depositing debris downstream as far away as present-day Reno.