New York is composite in drainage. The Hud son, with the Mohawk, drains much of its central and eastern lands, but is chiefly important for its tidal course of 150 miles, with great harborage at its mouth, and an open gateway to the west from the head of tide water. The Genesee, Black. and other rivers carry to the Saint Lawrence much of the run-off of northern and western New York. The Susquehanna, the Delaware, and the Mississippi take nearly all the remainder of New York waters. Inc most anomalous manner, due to glacial change of slope, the Allegheny gathers for the Gulf of Mexico waters that fall within a few miles of Lake Erie.
The Delaware, Susquehanna, and Potomac are all important rivers which rise in the Catskill Allegheny Plateau and find their way across the various mountain ridges of the Appalachian system by water gaps, and enter bays due to sinking of land and invasion of old valleys by the salt waters, In the plateau, where the strata are horizontal, the streams are dendritie, or finger-like, in arrangement. \Vithin the moun tain belt, the streams are in parts longitudinal, and in part transverse. By thus running be tween the ridges and cutting through them in water gaps, a rectangular or trellised drainage is formed Nvhieli is widely found in the Appalachian region. The northern Appalachian waters thus flow mainly to the open Atlantic. In the south,
however, or beyond the Potomac, the coastal rivers head in the eastern edge of the moun tains, while the Kanawha and the Tennessee, with their branches, head far across the moun tains and carry the waters to the Ohio River. The great core of the southern Appalachians, in western North Carolina, so convenient, it would seem, to the sea, is thus drained by a circuitous route into the Gulf of Mexieo.. The entire belt of Appalachian uplands has for the most part arrived at the stage of mature dissection, with abundant valleys, sunk from 500 to 1500 feet below the prevailing level of the uplands.
Many rivers of local importance rise on the eastern slope of the Blue Ridge, and cross the Piedmont Plateau and the Coastal Plain to the sea. Such are the James and other rivers of Virginia, the Roanoke, Cape Fear, Great Pedee. Savannah, and Altamaha of the Carolinas and Georgia. The rivers of Florida are mainly small, but have important tidal courses. The other Gulf drainage is overshadowed in magnitude by the Mississippi. The greater streams aside from this are the Chattahoochee, Alabama, and Tom bigbee on the east, and the Colorado (of Texas) and Brazos on the west, and the international Rio Grande. rising in Colorado and New Mexico.
THE Mississiem RIVER. See Mississtem RIVER.