Slump Features, Fayetteville Formation, Northwestern Arkansas

Abstract

ABSTRACT At a single outcrop of the Fayetteville Formation (Upper Mississippian) in northern Arkansas, a small portion of the section, consisting of alternating thin limestones and shales shows evidence of having slid or slumped, forming the following kinds of features: limestone mounds or rolls (slump balls), depression of beds under the mounds, irregular-shaped beds (slump sheets), beds which are sharply cut off, folding of beds, marked by recumbent layers of cherty limestone, and chert and limestone breccia. The fine-grained, unfossiliferous limestone containing up to 40 percent sapropelic material, suggests accumulation of these limestones under restricted marine conditions. The beds slid mainly from a northerly direction. The ultimate cause for the sliding is uncertain.