Ordovician and Silurian Strata from Well Core in Schoolcraft County, Michigan

The core recovered from a well drilled near the village of Cooks in the Northern Peninsula of Michigan reveals thicknesses of several Ordovician and Silurian formations. Several of these formations are incompletely exposed in natural outcrops. Below the glacial drift, the well penetrated 79.5 feet of Byron Dolomite of Burnt Bluff Group. Other Silurian strata encountered in the core include: Lime Island Dolomite, 27.7 feet; Moss Lake Formation, 121.2 feet; Cabot Head Shale, 87.3 feet; and Manitoulin Dolomite, 23.3 feet. Ordovician strata include: Big Hill Formation, 130.6 feet; Ogontz Member of Stonington Formation, 20.6 feet; Bay de Noc Member of Stonington Formation, 30.8 feet; Bills Creek Shale, 175.9 feet; and Collingwood Shale, 38.8 feet. The well terminated 72.1 feet into Trenton Limestone.