Till plains, moraines, kames, and esker systems of the Port Huron system are the predominant surface feature with relief of 50 to 60 feet. Pasture and crop land comprise approximately 63 percent of the basin and another 15 percent is comprised of forest. The harbor at Grand Haven has a minimum draft of 21 feet, and a channel 100 feet wide and eight feet deep extends 17 miles upstream. Above this point, the river is not suitable for commercial navigation. The Grand River Basin is underlain by two distinct groups of rocks, the younger glacial tills, and the older bedrock.
Glacial deposits are a mixture of rock material from many different sources.
This rock material was picked up, transported and deposited by glaciers or by waters flowing from the glaciers. The principal glacial deposits in the Grand River basin are till, moraines, outwash, and glacial lakebeds. The bedrock, that underlies the glacial deposits, was deposited in large inland seas that covered most of the area of the Great Lakes States. Bedrock formations are comprised primarily of sandstone, limestone, dolomite and shale, but include thick beds of salt, gypsum, and anhydrite. After deposition, the bedrock formations in the Great Lakes were warped into geologic structures that resembles a gigantic set of shallow bowls.