Glover Bluff, USA

Glover Bluff consists of three hills that rise about 35 m above the surrounding countryside. The crater area is located about 10 km NNW of the town of Westfield, Wisconsin. Aside from their geological interest (Ekern and Thwaites 1930), they have been important economically as the site of quarries that have mined the dolomite of Lower Ordovician age. Originally thought to be the result of graben faulting, the impact origin of the structure was only established in 1983, when shatter cones were discovered at the location of a newly established quarry at the top of the northern hill (Read 1983, 1984). The circular form of the crater, still not deeply studied, is inferred from the dip of the dolomite layer and from the detection of bedrock (sandstones) in water wells in the area (Cannon and Mudrey 1981).