departments of transportation. Environment The alpine tundra biome of the pass extends below it on either side to an elevation of approximately , or about the altitude of the Linkins Lake trailhead on the western side, Highway 82's uppermost crossing of the Roaring Fork. Below it is a subalpine zone where lodgepole pine, Engelmann spruce, subalpine fir and aspen dominate the forest. A few patches of those trees persist above that elevation, but they are mostly stunted krummholz. Tree growth above those patches is curtailed by the alpine climate of the pass. It is characterized by severe changes in temperature, high winds and the deep winter snow. The resulting short growing season is made even shorter by the thin soil. The most predominant plant species in the alpine zone around the pass are the grass species adapted to the harsh climate. Other alpine flora, such as moss and lichens on the rocks, and wildflowers in season, make appearances. Shrubs that survive among them include strawberry, snowberry, willows and bog birch. Animals in the alpine zone include ptarmigans, small burrowing species like pika, marmots, and pocket gopher, and mountain goats. Two types of rock are found in the pass and its vicinity. Quartz monzonite forms many of the cliffs, while the crags are biotite gneiss. The glaciation, which dates to as recently as 12,000 years ago, smoothed much of the rock to the point of it being slippery. Visitor attractions Many visitors stop at the parking lot and walk the paved path to the scenic overlook. In clear enough weather it offers views east of Mount Elbert, Colorado's highest peak, and La Plata Peak, the state's fifth-highest at . To the west more fourteeners—the Maroon Bells, Snowmass Mountain and Capitol Peak—stand out among the mountains. A trail with Braille interpretive plaques is available for visually impaired visitors. Other outdoor recreation opportunities exist at and near the pass. Between the pass and Difficult Campground, 3 miles (4.8 km) east of Aspen, there are many popular rock climbing areas, some with grades up to 5.12 under the Yosemite Decimal System. The Grotto Wall across from Lincoln Gulch campground is a frequent destination. Closer to the pass are Instant Karma Cliff and Putterman's Dome. A pair of rocks along either side of Highway 82 on the east approach to the pass are popular bouldering spots. On the days after the pass reopens in the