During the early stages of development at Red Wing Creek field, meteoritic impact was the accepted explanation for structure. Spectacular structure that apparently did not persist below the Mississippian Madison Group and the presence of shatter cones, which were thought to be indisputable proof of shock metamorphism from impact, were the primary points of evidence.

More subsurface information from new wells, and more careful correlation, subsurface mapping, and cross sections appear to indicate that there are two interpenetrating systems of fault slivers that persist down through the Ordovician Red River Formation. These fault slivers seem most likely to be torn from northeast- and northwest-trending, reactivated lineaments at their intersection. This deep structure, which is offset from the central high, supports the concept of at least 100 m.y. of progressive structural growth at Red Wing Creek field.

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In 1978, the presence of shatter cones was documented at the intersection of two major regional faults in the Canadian Slate Islands of Lake Superior. Thus it can no longer be concluded that shatter cones indicate shock metamorphism from meteoric impact exclusively.

These stratigraphic anomalies also support long-term structural growth at Red Wing Creek field. In the three highest wells, the Mississippian Charles Formation has no salt, which indicates that this 100-ac area was positive during deposition. Progressive, orderly absence of Mississippian and Pennsylvanian formations toward the central high of the pre-Amsden subcrop further substantiates major, late Paleozoic structural growth. Lack of breccia or meteoritic material in the Permian-Triassic Spearfish Formation and Jurassic Piper Formation ring-depression fill appears to rule out any explosive event. Instead of the normal gray Piper shales, there is much red shale within the Piper Formation at Red Wine Creek. This implies long-term, continued uplift rather than instantaneous impact and r bound.

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