 The valleys they occupy appear like immense ravines formed by some tremendous force that tore the solid rocks from their original beds, from the general level of the surrounding summits, down to the present bottoms of the lakes.Oneida and Onondaga lakes occupy level land in the northeast part of the Oswego Basin.Mud Creek, the most westerly branch of the Oswego River, takes its rise in Ontario County, flows northeast into Wayne County, where it unites with Canandaigua Outlet and takes the name of Clyde River; then it flows east to the west line of Cayuga County, where it empties into the Seneca River.