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 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 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 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