Geography of New York - Topography

Topography

New York lies upon the portion of the Appalachian Mountains system where the mountains generally assume the character of hills and finally sink to a level of the lowlands that surround the great depression filled by Lake Ontario and the St. Lawrence River. Three distinct mountain masses can be identified in the state. The most easterly of these ranges—a continuation of the Blue Ridge Mountains of Virginia—enters the state from New Jersey and extends northeast through Rockland and Orange counties to the Hudson River, continuing on the east side of that river as the highlands of Putnam and Dutchess counties. A northerly extension of the same range passes into the Green Mountains of western Massachusetts and Vermont. This range is known in New York as the Hudson Highlands. The highest peaks are 1,000 to 1,700 feet (300 to 520 m) above sea level. The rocks that compose these mountains are principally primitive or igneous, and the mountains themselves are rough, rocky, precipitous, and unfit for cultivation.

The second series of mountains enters the state from Pennsylvania and extends northeast through Sullivan, Ulster, and Greene counties, terminating and culminating in the Catskill Mountains west of the Hudson. The highest peaks are 3,000 to 3,800 feet (910 to 1,200 m) above sea level. The Shawangunk Mountains, a high and continuous ridge extending between Sullivan and Orange counties and into the southern part of Ulster County, is the extreme eastern range of this series. The Helderberg and Hellibark Mountains are spurs extending north from the main range into Albany and Schoharie counties. This whole mountain system is principally composed of rocks of the New York system above the Medina sandstone. The summits are generally crowned with red sandstone and with the conglomerate of the coal measures. The declivities are steep and rocky, and a large share of the surface is too rough for cultivation.

The third mountainous region, occupying the northeast part of the state, is known as the Adirondack Mountains. The region is bounded to the south by the Mohawk River, south of which the highlands become part of the Allegheny Plateau, in the form of broad, irregular hills, broken by the deep ravines of streams. The valley of the Mohawk separates the Allegheny Plateau to the south from the highlands leading to the Adirondacks to the north, reaching its narrowest point in the neighborhood of Little Falls, the Noses, and other places. North of the Mohawk the highlands extend northeast in several distinct ranges, all terminating upon Lake Champlain. The culminating point of the whole system, and the highest mountain in the state, is Mount Marcy, standing 5,467 feet (1,666 m) above sea level. The rocks of all this region are principally of igneous origin, and the mountains are usually wild, rugged, and rocky. A large share of the surface is entirely unfit for cultivation, but the region is rich in minerals, and especially in an excellent variety of iron ore.

In western New York, a series of hills forming spurs of the Allegheny Mountains enter the state from Pennsylvania and occupy the entire southern half of the west part of the state. An irregular line extending through the southerly counties forms the watershed that separates the northern and southern drainage; and from it the surface gradually declines northward until it finally terminates in the level of Lake Ontario. The portion of the state lying south of this watershed and occupying the greater part of the two southerly tiers of counties is entirely occupied by these hills. Along the Pennsylvania line they are usually abrupt and are separated by narrow ravines, but toward the north their summits become broader and less broken. A considerable portion of the highland region is too steep for profitable cultivation and is best adapted to grazing. The highest summits in Allegany and Cattaraugus counties are 2,000 to 2,500 feet (610 to 760 m) above sea level.

From the summits of the watershed, the highlands usually descend toward Lake Ontario in a series of terraces, the edges of which are outcrops of different rocks beneath the surface. These terraces are usually smooth, and, although inclined toward the north, the inclination is generally so slight that they appear level. Between the hills of the south and the level land of the north is a beautiful rolling region, the ridges gradually declining toward the north. In that part of the state, south of the most eastern mountain range, the surface is generally level or broken by low hills. In Manhattan and Westchester County, these hills are principally composed of primitive rocks. The surface of Long Island is generally level or gently undulating. A ridge 150 to 200 feet (46 to 61 m) high, composed of sand, gravel, and clay, extends east and west across the island north of its center.