Nearly In the middle of the mountain region runs the highest and widest of the ranges of the Allegheny Mountains. In the southern districts of Penneylvaela it forms the watershed between the rivers, which descend eastward to the Potomac and Susquehanna, and west ward to the Ohio ;, hut north of 41' N. lot, where it inclines to the north-east, the continuity is broken by the upper branches of the Susquehanna. The summit of this range is broad and nearly of equal elevation, being destitute of peaks. Its elevation above the sea, south of 41* N. let, seems to vary between 2000 and 2600 feet, and it stands on a hose from 800 to 1000 feet high and from 6 to 10 miles wide. East of this range there are five or six other ridges running parallel to each other. The most eastern, the Blue or Kittatinny Mountains, seems to be the highest, and in the Wind Clap, near Williamsburg, on the Delaware, attains the elevation of 1390 feet. The valleys inclosed by these several ridges rise In elevation as they approach the main Allegheny range; the most easterly being hardly more than 300 feet above the sea-leveL Both the ridges and the valleys are comparatively narrow, occupyiiig on an average only three miles In width. The declivities of the ridges are steep, and the valleys much depressed and , deep. The mountain region west of the main range consists, south of 41' N. lat., of two broad valleys and two ranges, called the Laurel Hills and the Chestnut Ridge. The valleys are about 1000 feet above the sea-level, and the ranges rise some 700 or 800 feet above them. The soil of this region is in general poor and stony, though the valleys contain some alluvial tracts of great fertility, but of inconsiderable extent. The winters are very cold and of long duration ; the snow covers the ground for several month,. The springs are wet; and the anmmere, though hot, of comparatively short duration. Maize does not ripen in most parts, and le only planted to be consumed before it gets rape ; wheat is only cultivated In sheltered places. The most common grains are rye and oats. The vegetables generally raised are seas, parsnips, carrots, onions, shallots, potatoes, sweet potatoes, and cabblges. The uncultivated portion of this region, which compre hends the greater part, is chiefly covered with forests. On the hither parts the ridges the mouutaius are covered with Cuniferte, as pitch, spruce. and white pines and cedars. In the valleys are oak and cheat- I nut, sod, where the soil is subject to inundations, sycamores. West of the Lanrel 1I111. the fonts are mainly composed of the broad leaved laurel, rhododendron, and Magnolia acuminata, mixed with chestnut-trees and some oaks.
The table-land of Pennsylvania, on the mountain region north of 41° N. lat., consists, as already observed, of wide broken plains with some ridges and some extensive swamps. The highest part of the table-land is contiguous to the boundary-line of New York, and rises to an elevation of about 1800 feet, with a few ridges wbioh are a few hundred feet higher. Along the water-courses the table-land is de preaaed, sometimes above a hundred feet, and in these districts alone rye, oats, and some vegetables are oultivated. There are however extensive pastures on the higher parts. The climate is still more severe than it is between the ridges farther south, as the low ridges cannot shelter the plains against the prevailing north-west winds. The forests of the higher land are almost entirely composed of Coni fers, but they do not contain nanny timber-trees, the stony soil being too poor for their growth. In the depressions and along the rivers are sugar-maple, black walnut, elm, and beach.
3. The Korth-Western Region constitutes the most eastern portion of the plain which slopes from the base of the Allegheny Mountains westward to the banks of the Mississippi. Near the foot of the moun
tains it is from 900 to 1000 feet above the sea, and where it approaches the boundary-line of Ohio it is still nearly 700 feet above it, in the valley of the Ohio, but much higher farther northward, where it pre serves the elevation of from 000 to 1000 feet to the very boundary line. The surface of this region is undulating, the ascents being gentle and the upper part of the eminences broad, with a rounded outline, except along the watercourses of the larger rivers, where the ascent is rather steep. The soil varies very much : in many places there are large tracts with a poor and stony soil ; in others, especially along the rivers, there are fertile tracts. The climate does not mate rially differ front that of the south-eastern region, except that the winters are colder, and the quantity of rain which falls is not quite so great. In the southern districts cultivation has made considerable progress, and the country presents a pleasing variety of fields and forests. All the grains of the south-east region are raised in abun dance, and the orchards produce great quantities of fruit, especially apples and cherries. The forests consist chiefly of oak and auger-maple. The northern districts are almost entirely covered with forests, con sisting of hemlock, spruce, and Weymouth pine, which attains a great size, intermixed with beech, birch, and sugar-maple.
I(ydrogropAy ; Communications. —The most important river of Pennsylvania is the Delaware, which is navigable by large ships to Philadelphia, and by sloops to Trenton, 130 miles from its mouth. [Detawanz.) The Susquehanna rises iu two branches on the table lands of Pennsylvania and New York, of which the eastern branch originates near 74' 40' W.long., and the western near 73° 40' W. long., and consequently more than 200 miles from each other. The eastern and principal branch has its source in Lake Otsego, near the western declivity of the Tuscarora Mountains in New York, traverses the table-land of New York in a south-western and western direction, and after a course of about 140 miles enters Pennsylvania, and ie soon after wards joined by the Tioga River, which Collects its waters on the tableland farther west, and flows about 30 miles. From the junction with the Tioga it flows about 180 miles south-east, and afterwards south west, to itsjunction with the western branch. This western branch, which is exclusively a river of Pennsylvania, originates in the moun tainous tract south of 41° N. lat., and after a northern and eastern course of about 140 miles, it turns southward about 25 miles and joins the eastern branch above Sunbury. After the union of the two branches, the Susquehanna runs southward for about 50 miles, traversing by narrow valleys five or six of the ridges, which here lig between the table-land and the south-eastern region. Before it reaches the lower country it receives on its right bank the largest of its affluents, the Juniata, which rises on the western declivity of the Allegheny Mountains, and runs iu a circuitous course for about 150 miles, collecting in its way by far the greater part of the waters in the eastern part of the mountain region south of 41° N. 6t. After having left the mountain region above Harrisburg, the Susquehanua is joined by the Swntara Creek, whose course hardly exceeds 50 miles, and by several other small streams. Tho course of the Susquehanna through the southeastern region is about 170 miles; its entire course is some under 450 miles. It is navigable by sloops for about 5 miles; butabove that navigation is impracticable, owing to the rapidity of the current and the numerous rocky ledges which form numerous rapids.