ZOOMED AERIAL & DIGITAL TOPOGRAPHY
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Besides elevation, there are two other important characteristics for characterizing the topography of a landscape - slope and aspect. Slope is a measure of how steep the land is, and aspect is the compass direction in which the slope faces. Slopes in the Catskills range from nearly flat areas along our larger river valleys, to vertical cliff faces; aspects of Catskill mountainsides face all directions. Variations in slope and aspect affect other natural processes. Steep slopes mean rocky, fast streams that generally have a ‘step-pool’ formation, and rivers on more gentle slopes tend to move slower and have ‘riffle-pool-meander’ formations.

Slope, aspect, and elevation, along with other factors such as moisture and soil depth, also profoundly affect the composition of forest vegetation. The majority of the Catskill forest is comprised of northern hardwood species, which are predominantly sugar maple, yellow birch, and American beech, along with lesser amounts of white ash, black cherry, hop hornbeam, red oak, eastern hemlock, and white pine. The eastern Catskill escarpment, along the Hudson Valley, is drier and contains much more red oak, chestnut oak, hickory, white pine, pitch pine, and delicious blueberries and huckleberries. The lower, broader river valleys are likely to contain species such as black locust, sycamore, poplar, and willow. As one climbs higher into the mountains the relative numbers of birch, black cherry, and red maple increase, and then at several of our higher summits we see a cap of balsam fir and red spruce, along with white birch and mountain ash. Ravines with steep slopes are often cloaked in stands of pure eastern hemlock, and cliff faces sometimes hold some tenacious trees and delicate ferns. Aspect comes into play also, with north-facing slopes receiving less sunlight and hosting a greater proportion of cold-hardy species, and south-facing slopes often being drier and containing plants more suited to the lack of moisture.