July 19, 2004
This photo was taken on June 21, 2004 from the top of Algonquin Peak in New York's Adirondack Mountains. The view is east toward Mt. Colden (center), and Mt. Marcy (at 1629m (5344ft) the highest point in New York) dominates the horizon. The Adirondack High Peaks are developed on a huge Precambrian 'metanorthosite' dome that continues to rise up out of the northeastern corner of New York State. A thin veneer of soil, often less than a meter thick and held in place by a tangle of tree, shrub, and grass roots, clings tentatively to the steep slopes on the flanks of many of the High Peaks. Heavy rains can saturate those soils and lubricate the surface of the rock they cling to. If the weight of the saturated soils exceeds the friction holding them in place, huge landslides can, and often do, occur. The west flank of Mt. Colden (pictured here) is well known for its dramatic slides.
In the fall of 1999, several large slides were triggered when the remnants of Hurricane Floyd delivered 10% of the annual regional precipitation in a single day! The newly exposed rock beneath those slides on Colden appear much whiter than the more weathered surfaces of the old slides. Note in particular the long, new slide on the left (northeast) side of Mt. Colden. A huge mass of trees, soil, and rock that used to cover this slope slid down into Avalanche Pass, blocking a popular hiking and skiing trail there and forcing several hikers to find another way out of the High Peaks that week. The trail has since been cleared and reopened, but the slide and pass have been closed to hikers and skiers several times during the winter due to the increased threat of snow avalanches on the new slide. On the inset photo (lower left) is another view of the same slide taken from a point north of Mt. Colden.