TY - RPRT TI - Isopach mapping by photogeologic methods as an aid in the location of swales and channels in the Monument Valley area, Arizona AU - Irving Jerome Witkind AU - William R. Hemphill AU - Charles L. Pillmore AU - Robert H. Morris PY - 1953 DO - 10.3133/tei431 UR - https://pubs.usgs.gov/publication/tei431 ID - tei431 ER -