/Big Cusp algal dolomite member (informal) of Kona Dolomite of Chocolay Group of Marquette Range Supergroup. Authors use nomenclature of G.L. Taylor (1972, Michigan Tech Univ., Ph.D. dissertation). Kona Dolomite comprises (ascending) gray argillite, lower quartzite, cherty dolomite, gray-green argillite, middle quartzite, Big Cusp algal dolomite member, Valley member, color-banded dolomite, upper quartzite, Ragged Hills member, and upper dolomite. Big Cusp is 35 m thick and consists of a lower argillite, lower carbonate, middle argillite, middle carbonate, upper argillite, and upper carbonate. Name is derived from large domal stromatolites in upper carbonate. Occurs on eastern Marquette Range. Deposited on shallow, restricted marine shelf.
Exposures at Lake Superior, 5 km south of Marquette, off State Highway 41, eastern Marquette Range, Northern Peninsula, northwestern MI. Big Cusp is not a geographic feature; origin of name is from the large domal stromatolites in the upper carbonate.

Source: GNU records (USGS DDS-6; Reston GNULEX).