Subsection is cooler than most of the rest of southern Lower Michigan. Because most air flows here are from a westerly direction, this subsection experiences less lake moderation than subsections on the west side of the State. The highest rainfall and snowfall occurs at the northeastern edge of the subsection along Lake Huron, where lake-effect precipitation occurs when winds are from the north and east. Bedrock is covered by glacial deposits, except on lower reaches of some of the streams and small portions of the shoreline of Saginaw Bay and Lake Huron. Bedrock includes Mississippian shale, sandstone, gypsum, and limestone.
Mississippian sandstone is exposed in the north, along Lake Huron.
Pennsylvanian-age coal was mined locally.