Ashton Anticline (New Name)
Part of the Sandwich Fault Zone
Old Name: Ashton Arc
Location
Southeastern Ogle, northeastern Lee, and southern De Kalb Counties (B-5, 6)
References
Willman and Templeton 1951, Templeton and Willman 1952, Green 1957, Kolata et al. 1978, Kolata et al. 1983
Description
The term "arch" denotes a feature such as the Kankakee or Cincinnati Arch, which are regional in extent. Because this feature is a local and not a regional structure, its name is changed from Ashton Arch to Ashton Anticline. The axis of the Ashton Anticline is about 1 mile (1.6 km) southwest of and parallel to the Sandwich Fault Zone (fig. 17). The southwest flank of the anticline is broad and has an average dip of only 50 feet per mile (1/2°). The short northeast flank is relatively steep and truncated by the fault zone. Closure on the anticline has been mapped only in a small area that straddles the Lee-Ogle county line (Kolata et al. 1978).
The structure of the Ashton Anticline suggests that an underlying basement block was uplifted and tilted southwestward along the Sandwich Fault Zone. The steep northeast limb of the anticline may be the product of drag or forced folding along the fault zone.
Figure(s)
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