Interim geologic map of the Little Drum Pass quadrangle, Millard County, Utah (OFR-423)

By: L. F. HintzeThis quadrangle covers most of the Little Drum Mountains, which is a small northwest-trending range in the Basin and Range Province. The Little Drum Mountains are about six miles across at their widest and about 20 miles long. The southeastern end of the range is about 20 miles west of Delta, Utah. Excellent bedrock exposures reveal that the range is almost entirely made up of rocks of volcanic origin ? lahars, lava flows, ash-flow tuffs, and volcanic conglomerate and sandstone ? that are late Eocene in age. These volcanic rocks were likely derived from eruptive centers to the north in the adjacent Drum and Keg Mountains. The Little Drum Mountains were later tilted into a west-dipping homocline during Basin and Range faulting. Information in this publication includes: text description of the geology history of the quadrangle, a lithologic column, and a correlation chart of map units. This Open-File release makes information available to the public during the review and