Plunketts Creek 's unique name come from the first owner of the land including the creek 's mouth , and the creek have given its name to two townships ( although one have since changed its name ) . The creek flow southwest and then south through the dissected Allegheny Plateau , through rock from the Mississippian sub @-@ period and Devonian period . Much of the Plunketts Creek valley is composed of various glacial deposits , chiefly alluvium .