These two gullies are located 175 and 300 yards south of the Powder River bridge on U.S. Highway 14 and 16, 3 miles north of Arvada, Wyoming. They are included on the topographic map published by the U.S. Geological Survey entitled "Sheridan, Wyoming; Montana," scale 1:250,000, part of which appears in this folder, see figure 1. The coordinates are lat. 44°41'12" N., long. 106°06'38" W. at R. 77 W. along the boundary between T. 54 N. and T. 55 N.
Both gullies are graded from the middle (Moorcraft) river terrace to the low (Lightning) terrace level. The Moorcraft surface is essentially flat and featureless. The Lightning terrace is narrow, but also essentially flat except where flow from the gullies have incised a low water channel laterally across this surface. The average elevation of the sites is about 3700 feet above sea level. Annual precipitation is about 13 inches. Vegetation is various range grasses, especially bluestem and cheatgrass, and sagebrush (Artemisia).
At the time of preparation of this file, the site had been visited three times: July 18, 1950, July 31, 1962, and June 6, 1963. The 1950 survey consisted of a planetable map showing the outline of the gullies and some spot elevations (figures 2 and 3). No permanent reference points were established during this survey. The 1962 survey consisted of more detailed planetable mapping and the establishment of two permanent reference points at each gully for future orientation and elevation (figures 2 and 3). Each benchmark is a four-foot length of 1/2-inch diameter steel rod driven into the ground and protruding about six inches above the ground surface. Black and white and color photography was taken in 1962 and 1963. Low altitude aerial photography was taken in 1963.
The original field data are on file with William W. Emmett, U.S. Geological Survey, Washington, D.C. 20242, U.S.A. The file includes the original planetable surveys and film negatives.