The "V" course of the Cuyahoga River is rather unusual, first flowing southwest, and then abruptly turning north to drain into Lake Erie not far from its origin. The left arm of this "V", flowing north through the park, corresponds to an older preglacial valley, while the right arm corresponds to relatively new drainage. The new segment cut into the old at Cuyahoga Falls, the base of the "V". Other streams have made routes into the Cuyahoga preglacial valley by cutting gorges with waterfalls such as those found along the Tinkers, Brandywine and Chippewa Creeks. These waterfalls form as flowing water erodes the Bedford Shale, which underlies the more resistant Berea Sandstone. Glacial drift fills the valley to a depth of . This fill is very complex due to ponding in front of the ice before and after each glaciation. Beach deposits, gravel bars and other shoreline deposits from Lake Maumee are found in the valley, as are gravels from the time of Lake Arkona, and ridges marking the shores of Lake Whittlesey, Lake Warren, and Lake Wayne.