Black Jack Syncline

Part of the Upper Mississippi Valley Zinc-Lead District

Location

T27N, R1E, Jo Daviess County (A-3)

References

Willman and Reynolds 1947, Bradbury et al. 1956

Description

The Black Jack Syncline was extensively mineralized with zinc and lead, and mapped from mine and borehole data. It is a sharp, narrow fold at least 2.7 miles (4.5 km) long and 200 to 500 feet (60-150 m) wide; it has maximum relief of about 30 feet (9 m). Like other synclines in the Galena district, it may be the product of solution collapse.