The region discussed is that part of the Allegheny plateau in western New York which lies between the Canandaigua valley on the east and the valley of the Genesee river and its tributary, Canaseraga creek, on the west. It covers the northward slope of the plateau, here about 20 miles long. At its northern limit the distance from the foot of Canandaigua lake to the Genesee river is 25 miles. It is bounded on the south by the Cohocton-Wayland valley, which connects the head of Canaseraga with the head of Canandaigua, only 10 miles apart. It includes the four western finger lakes—Honeoye, Canadice, Hemlock, and Conesus—all of which are tributary to the Genesee. The plateau rises from an elevation of about 800 feet on the north to a crest above 2,000 feet in the southern part of the region. Its northern third is underlain by the . . .