Top Trails: Lake Tahoe. Mike White

      Introduction to Lake Tahoe

      Tall mountains covered with a thick blanket of conifers surround the breathtakingly blue lake, creating a stunning, alplike setting, which is famous around the globe. Whether you plumb the depths of Lake Tahoe, climb to the summit of the highest peak, or journey somewhere in-between, the Tahoe Basin provides many opportunities to appreciate the grandeur of one of the West’s most priceless treasures.

Geography and Topography

      The Lake Tahoe Basin presents diverse topography that receives adoration from a devoted tourist base. At an elevation of 6,229 feet, Tahoe is the highest lake of its size in the United States and, with a depth of 1,645 feet (measured near Crystal Bay), is the third deepest lake in North America and the 10th deepest lake in the world. The 22-mile-long and 12-mile-wide lake has a 71-mile-long shoreline, with 42 of those scenic miles belonging to California and the remaining 29 owned by Nevada. Lake Tahoe is perhaps best known for the crystal clarity of its waters, which allows visibility of up to 75 feet below the surface. Sixty-three streams flow into Lake Tahoe, but only one, the Truckee River, flows out of the lake, reaching its terminus in the Great Basin, at Pyramid Lake.

      Geologists speculate that the landform that would ultimately become the Tahoe Basin we know today was once beneath a shallow ancient sea in the supercontinent of Pangaea. The North American Continental Plate eventually broke away from Pangaea and headed west, colliding into the Pacific Ocean Plate, which was drifting east. Extreme pressure and heat were created as the North American Plate rose above the Pacific Plate, producing molten rock that slowly solidified beneath the sedimentary surface into granitic rocks, which were later exposed through faulting.

      Faulting fractures in the earth’s crust allowed blocks of land to rise and fall, pushing the primarily plutonic rocks of the Sierra Nevada up from the ancient seabed. Two principal faults evolved in the Tahoe area, which produced uplifts that became the main Sierra Crest to the west and the Carson Range to the east. In between, the down-thrown fault block formed the deep V-shaped valley of the Tahoe Basin.

      A lake began to form at the lowest, southern end of the basin, fed by precipitation and creeks draining the surrounding mountains. The level of the lake rose steadily, until an outlet for the river draining the lake was reached to the north, near the current town of Truckee. Later, a significant lava flow from Mount Pluto, site of the Northstar California Resort, dammed the outlet and caused the lake to rise again. Eventually the river was able to cut a new outlet through the volcanic rock, near the present-day Tahoe City. The highest level Lake Tahoe ever reached was an estimated 600 to 800 feet above the current level. Additional volcanic activity occurred at both the south end of the basin, around Carson Pass, and the north end of the basin, near Donner Pass.

      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.

Flora

      Because the area ranges in elevation from 6,229 feet at lake level to 10,881 feet at the summit of Freel Peak, you can expect to encounter a wide range of flora on trails within the Tahoe Basin. The mountains and hills surrounding the beautiful shoreline of Lake Tahoe are carpeted with conifers. Though it’s hard to believe at first glance, these trees belong almost exclusively to a second-growth forest, as the basin was nearly denuded to provide timber and fuel for Virginia City and the surrounding mines during the heyday of the Comstock Lode. Though the varied vegetation defies strict classification, the following zones provide a general overview of Tahoe’s flora.

      The upper montane zone, the largest zone in the basin and containing the widest variety of plant types, runs from lake level to about 8,000 feet. The upper montane zone can be grouped into six distinct divisions. Up to around 7,000 feet, the white fir forest is named for the dominant member of a mixed forest, which also includes incense cedar, sugar pine, Jeffrey pine, and ponderosa pine, as well as red fir at the upper limits. Preferring a moist habitat, the white fir forest can form dense stands with little ground cover, or more open stands allowing deciduous trees and shrubs to thrive, including quaking aspen, willow, maple, currant, gooseberry, thimbleberry, and honeysuckle. Above the white fir forest, the red fir forest extends to about 8,500 feet. Unlike the white fir forest, red fir is found in exclusive stands, usually on cool northern or eastern exposures. The red fir forest is generally dense, allowing very little ground cover, which when present is composed primarily of shade-loving flowers and plants. The Jeffrey pine forest occupies drier slopes than those preferred by the white and red fir forests. Spanning elevations from lake level to approximately 8,000 feet, open Jeffrey pine forests intermix in the lower realms with sugar pine, ponderosa pine, white fir, and incense cedar. Those conifers are replaced by western white pine, ponderosa pine, and red fir toward the upper limits.

      On southern exposures, light stands of Jeffrey pine forest oftentimes intermix with Sierra juniper or with open areas of montane chaparral. The drought-tolerant montane chaparral community spans elevations across the spectrum of the upper montane zone into the subalpine zone, typically occupying dry slopes with a southern exposure. This community incorporates several common shrubs, including huckleberry oak, tobacco brush, rabbitbrush, manzanita, chinquapin, and sagebrush. Along the eastern fringe of the Carson Range, mountain mahogany and juniper trees may dot the slopes of the montane chaparral community. Areas of sufficient groundwater produce the montane meadow community. Similar to the montane chaparral community, montane meadows span the realm of the upper montane zone into the subalpine zone. The wetter environment allows grasses, rushes, and sedges to thrive, along with several species of water-loving wildflowers. The last of the five classifications within the upper montane zone is the riparian community. With the additional moisture provided by perennial streams, lush foliage along the banks includes deciduous trees and shrubs such as aspen, cottonwood, willow, alder, creek dogwood, and mountain ash. Smaller plants and colorful wildflowers are also common in creek-side environments.

      Above the upper montane zone, the subalpine zone begins around 8,000 feet and continues upward to timberline, which, depending on a number of variables, starts anywhere from 9,000 to 10,000 feet in the Tahoe Sierra. With characteristically poor soils and a harsh climate, where snow covers the ground for nine months of the year, the prolific forests below give way to isolated stands of conifers and the open terrain of meadows and talus slides. Red firs, lodgepole pines, and junipers may extend into this zone in some areas, with lodgepole pines often rimming the shoreline of subalpine lakes. Despite the sporadic appearance of these trees from the lower realm, the two conifer species most closely associated with the subalpine zone