The west side of the Bay is a gentle dip slope on the top of the Platteville-Galena dolomites. From well data, the contact with the Maquoketa Formation is probably about at the Fox River. There are a number of outcrops and quarries near the west shore of the bay. The hilly terrain west of the Bay is due to glacial deposits on top of the bedrock. This bench mark lies about 20 meters west of the end of the sidewalk along the shoreline at Bay Beach.
Bench marks are the precisely-surveyed points that are the basis of all detailed maps.
In 1973 the shore areas of Green Bay were badly flooded. To guard against future flooding, this dike was built along the shore. The large blocks of stone and concrete rubble, termed riprap , serve to protect the dike from wave erosion. The CDF is a depository for polluted dredged materials from the Green Bay harbor entrance channel. The island is 800 feet offshore from Bay Beach.