Denali National Park
|Denali National Park (courtesy, NPS)|
Mount McKinley reigns in lofty isolation over the Alaska Range, that magnificent 600-mile arc of mountains that divides south-central Alaska from the interior plateau. Its life as a mountain range began some 65 million years ago, the result of the Denali Fault, North America's largest crustal break. This fault, where two tectonic plates have moved against each other, stretches for 1,300 miles from the Yukon border down to the Aleutian peninsula. There the Alaska and Aleutian Ranges meet in a mad jumble of peaks that includes active volcanoes. Earthquake tremors both mild and moderate are frequent occurrences in the park and preserve.
The building of these massive mountains began out of a flat lowland. The material that Earth's inner turmoil thrust up has subsequently been eroded, sculpted, and weighed down by huge masses of ice. Numerous glaciers still radiate from the high peaks of the Alaska Range, where the frigid temperatures prevent their melting. Some of the glaciers are visible from the park road. The debris-laden snout of the 35-mile-long Muldrow Glacier lies within a half mile of the park road. The park and preserve owes its beautiful landscape contrastswide, low plains and dark, somber mountains; brightly colored peaks and sheer granite domesto the Denali Fault. Geologists say that Mount McKinley still rises today.
More than 430 species of flowering plants as well as many species of mosses, lichens, fungi, algae, and others grace the slopes and valleys of Denali. Only plants adapted to long, bitterly cold winters can survive in this subarctic wilderness. Deep beds of intermittent permafrostground frozen for thousands of yearsunderlie portions of the park and preserve. Only the thinnest layer of topsoil thaws each summer to support life. After the continental glaciers retreated 10,000 to 14,000 years ago, hundreds of years were required to begin building new soils, and to begin the slow process of revegetation. Denali's lowlands and slopes consist of two major plant associations: taiga and tundra.
Taiga (pronounced ti-ga), a Russian word for northern evergreen forest, describes the scant tree growth here near the Arctic Circle. Much of the park and preserve's taiga lies in valleys along the rivers. White and black spruce, the most common trees, are interspersed with quaking aspen, paper birch, alder, and balsam poplar. Stands of deciduous trees occur along streamside gravel bars or where soils have been disturbed by fire or other action. Woods are frequently carpeted with mosses and lichens. Many open areas are filled with shrubs such as dwarf birch, blueberry, and a variety of willow species. The limit of tree growth occurs at about 2,700 feet in the park and preserve. For comparison, the elevation at the park hotel is 1,750 feet. Above the tree limit, taiga gives way to tundra.
Tundra is a fascinating world of dwarfed shrubs and miniaturized wildflowers adapted to a short growing season. There are two types, moist tundra and dry tundra, with myriad gradations in between. Moist tundra varies in composition: Some areas contain tussocks of sedges and cottongrass; others contain dwarfed shrubs, particularly willows and birches. Plants of the dry tundra live scattered among barren rocks at higher elevations. Tiny highland plants grow closely matted to the ground, creating their own livable microclimate. Flowered dry as, dwarf fireweed, moss campion, dwarf rhododendron, and forget-me-not (Alaska's state flower) dot the rocky landscape, offering stunning summer displays of delicate blossoms. Although small in stature, they loom large in importance because their nutrients provide food that sustain even the largest species of park wildlife.
Details mentioned in this article were accurate at the time of publication