Deformation at Elk Knob State Park

A History of Folding and Faulting

Rocks at Elk Knob show evidence of at least four stages of folding and two periods of faulting.

These ~NS-trending folds formed early in the deformation history of Elk Knob. The folds shown here are called isoclinal folds. "Iso" means same and "cline" means angle, so these folds are called such because the limbs of the fold parallel each other, or are at the same angle.

 

Triassic sediments
Piece of amphibolite float (rock not in place) with early formed, isoclinal fold that is refolded by a later, open fold.
Complex fold patterns like this support multiple stages of folding during mountain building at Elk Knob. The rock pictured is garnetiferous amphibolite interlayered with quartzo-feldspathic gneiss. This "interlayered amphibolite" occurs within the middle schist unti at Elk Knob. Triassic Sandstone

The contact (or boundary) between the schist and under- and overlying amphibolite bodies is an ancient fault. This picture shows evidence of fault movement preserved in the schist as rootless folds and stretched quartz lenses. These features indicate that Elk knob rocks were hot and ductile at the time of faulting.

Triassic Conglomerate