Typical gorge in Minnekahta limestone, invading valley of Spearfish Red shale west of Hermosa, Lawrence County, South Dakota, circa 1904, plate 8-A in U.S. Geological Survey. Professional paper 65. 1909. Plate 21 in U.S. Geological Survey. Folio 219, Professional Paper-0065
1925.
Digital File:jta00034