Of the four grape regions of New York the Chautauqua district is by far the most important though, excepting the Niagara, the most recent in development. The Chautauqua grape belt lies along the southeastern shore of Lake Erie. It averages about three miles in width and is about fifty miles long. Its northeastern boundary is in Erie County but not far from the line dividing Erie and Chautauqua Counties; its western boundary, in New York, is the Pennsylvania line, an arbitrary division, for the district passes into Pennsylvania. This narrow belt passes through the towns of Hanover, Sheridan, Dunkirk, Pomfret, Portland, Westfield and Ripley in Chautauqua County. Not all, but much, of the land is suitable for grape-growing. The topography, geology, and soils of this grape-belt have been carefully mapped and studied.[93][94] The grape land is, as we have seen, a narrow strip of comparatively low land which borders the shore of Lake Erie. On the southern boundary of this low plain is a high hill or escarpment parallel to the lake and surmounting the grape belt throughout its entire length. This escarpment, the "Hill", ranges from 500 to 700 feet above the plain and from 500 to 1000 feet above the lake. The plain is gently rolling and ascends from the bluff of the lake to the escarpment with a grade of from one to two hundred feet to the mile, forming in some places well-marked foot-hills to the escarpment proper. The bed rock, according to Tarr[95] is upper Devonian shales and sand stones in both plain and escarpment. On the face of the escarpment and on the table lands of some of the foot-hills the soil is so thin that the plough frequently touches bed rock. This seldom comes to the surface on the plain except in stream beds and in shale ridges, but is to be found in fragments of greater or less size and in more or less abundance throughout the soils of the entire district. Everywhere on the plain may be seen ancient beach lines. These rise usually in two well-defined terraces but not infrequently there are from two to five distinct terraces between the lake and the escarpment. All conditions point to the theory that these ridges are wave built and therefore of lake origin. The plain, the gravel ridges, the foot-hills and the high escarpment are the chief topographical features of the grape belt. The grape soils of the district, as mapped by the Bureau of Soils of the United States Department of Agriculture,[96] are Dunkirk clay, Dunkirk gravel, Dunkirk gravelly loam, Dunkirk sandy loam and Dunkirk shale loam. The grapes grown upon the several soils vary somewhat as to quantity per acre, as to flavor and sugar content and as to shipping quality.