Leaf River Anticline

Part of the Plum River Fault Zone

Location

North-central Ogle County (A-5)

References

Buschbach and Bond 1974, Kolata and Buschbach 1976, Kolata et al. 1983

Description

This anticline is located immediately south of the Plum River Fault Zone near the east end of the fault zone (fig. 37). It trends east to west and is about 6 miles (10 km) long and 2 miles (3 km) wide. Closure on the Ordovician Glenwood Formation is approximately 80 feet (25 m). The Leaf River Anticline was also mapped on the Cambrian Franconia Formation (fig. 17), and small faults have been observed in outcrops along the crest of the anticline (Kolata and Buschbach 1976). The close relationship of the anticline to the fault zone suggests that they formed under the same stress regime.

Figure(s)

Figure 17   Structure map of the top of the Franconia Formation (Upper Cambrian)in northern Illinois. Contour interval is 100 feet. From Kolata et al. 1983. Figure 37   The Plum River Fault Zone and related structures, northwestern Illinois. Structure contours on top of the Glenwood Formation (Middle Ordovician). After Kolata and Buschbach 1976. Contour interval is 50 feet.