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Inland from the Atlantic coastal plain is a belt underlain mainly by very old rocks, much deformed, generally metamorphosed and resistant. This belt extends from central Alabama north-eastward into Canada, but the part to be described here terminates at Hudson river. Its greatest width in the south is nearly 200 m., but north of Potomac river it averages barely 6o miles. This relic of the early Paleozoic continent is marked now by a mountain range on its north-western side. From southern Pennsylvania, where it is called South Moun tain, to southern Virginia, where it is called Blue Ridge, it is rarely more than i o or 15 m. wide and from 1,500 to 3,00o f t. high. In North Carolina and adjacent States it broadens to 7o m. and cul minates in Mt. Mitchell (6,711 ft.), the highest point in eastern United States. The range is interrupted by a short gap in south ern Pennsylvania. North-eastward from this gap it is known as the Highlands of New Jersey and New York. This part, being detached from the main range (Blue Ridge Province) and con tiguous with the New England province, which is largely of the same character, is considered a part of the latter. From New England to southern Virginia the crest as viewed from a distance is gently undulating and is considered to be the remains of an uplifted peneplain preserved by the strength of the rocks, while weaker rocks on both sides have been reduced to a new and lower peneplain. In western North Carolina the ancient mountains were not all worn down to the peneplain indicated by the crest farther north. Partly for this reason and partly because of greater recent uplift these mountains are several thousand feet higher.
Between the mountains and the coastal plain is the Piedmont province, most of it a low plateau sloping seaward, consisting in the main of the same rocks found in the mountains. Where the rocks of the piedmont and mountain belts are similar the existence of a newer and lower peneplain in the former and not in the latter is explained by the fact that the new peneplain developed first along the lower courses of streams flowing from the mountains to the sea. It spread westward, its limit of advancement being the eastward slope of the Blue Ridge. This newer peneplain is itself uplifted and dissected by revived streams. Much of the northern end of the Piedmont province in Pennsylvania and adjacent States is exceptional, consisting of softer Triassic rocks. As these were more readily worn down and, as already pointed out, the conti nent in this latitude has been less uplifted, this part of the Pied mont province is lowland rather than plateau, though still dis tinctly higher than the coastal plain. Taken as a whole the rocks of this province are not very good soil makers, but the position, especially of its northern part, favours intensive cultivation. Parts of the upland farther south are adapted to fruit trees and an important cotton district in South Carolina is in this province.
The New England province is a broadened north-eastward extension of the belts already described. It has the same rocks along with some younger Paleozoics, gen erally deformed, metamorphosed and peneplaned. Residual moun tains rising above the general level to an altitude of 4,000 to 6,000 ft. are found in the Green mountain section of Vermont and Massachusetts and the White mountain section of New Hampshire and Maine. Between and around these mountains the upland level is generally a little above i,000 ft., studded here and there with isolated residual mountains or "monadnocks," the original Mount Monadnock being in south-western New Hampshire. This upland is an uplifted peneplain, itself dissected by sharp valleys since uplift. The surface declines seaward to the "Seaboard Lowland" and it is probable that newer and lower peneplains are here repre sented. The coastal margin below a level of 500 ft. has a rolling surface with wide open valleys in contrast with the narrow and steeper valleys that incise the plateau. The land below Soo ft. also includes the broad valley of Connecticut river carved from Tri assic rocks and analogous in most ways to the low northern end of the Piedmont province. With this valley included, the relatively narrow seaboard lowland contains the greater part of New Eng land's population and industry.
Elevation was followed by depression and the valleys are drowned. This is typically shown on the coast of Maine where the style of depressed coastline is quite different from that of the coastal plain because of difference in topography previous to drowning. Outlying islands, formerly hills or mountains of hard rock, are abundant here. Harbours are numerous and fishing is favoured by this as well as by the broad continental shelf.
Unlike the Piedmont and Blue Ridge provinces, New England was severely glaciated, its mountains overridden and scraped by the continental ice sheet, and its surface generally covered by ice-laid drift abounding in boulders. Some of its valleys are partly filled with sandy outwash. Both topography and the stony soil are unfavourable to agriculture. The northern part of the province was long the great lumbering district of eastern United States. One of the chief effects of glaciation was the dislocation of streams. Drainage in beginning anew was obliged to fill many basins and cross many rocky ledges. Lakes and rapids, therefore, abound, the latter being a great source of power. New England, with its poor soil, abundant water power and excellent harbours early developed manufacturing and commerce.
In its physical geography the Adirondack area in northern New York is much like northern New England, a combination of subdued mountains and hilly plateaux, all severely glaciated and abounding in lakes. Like the White Mountains and New England coast it is much used as a summer resort. The State of New York has reserved large areas of forest.