West Branch State Park is located on the west branch of the Mahoning River in Portage County. In 1965, the Michael J. Kirwan Reservoir was completed on the river for flood control, water supply, recreation, and fish and wildlife management. However, detailed geologic information of the park is lacking for the public to understand its ancient history. A detailed investigation was conducted to better constrain the geologic history of West Branch State Park.

Detailed information of the park was gathered through extensive fieldwork and published data. Bedrock and glacial geologic maps were constructed using ArcGIS and MicroDEM mapping programs. Thickness of glacial material and bedrock formations were determined using ground water well data. A north-south cross section through the park was produced, showing the geology in the third dimension.

West Branch State Park is situated on the glaciated plateau of northeastern Ohio where Pleistocene glaciers were able to override the gentle hills and stream valleys of the land formerly uplifted as part of the Appalachian Mountain building process. The subsurface bedrock units in the park consist of Devonian to Pennsylvanian shales and sandstones. The bedrock was covered by several ice advances of the Wisconsinan Glacier that left behind three distinct glacial features: a buried stream valley filled with ~350 feet of drift material, now occupied by the present stream and reservoir; ground moraine, ~15 feet thick, covering the hills on the southern section of the park; and the Kent End Moraine on the northern part of the park.