Applicability of ERTS-1 to Montana geology
The author has identified the following significant results. Geologic maps of four test sites were compiled at 1/250,000. Band 7 prints enlarged to 1/500,000 scale are the best for the purpose, and negative prints provide a valuable supplement. More than 100 mapped lineaments represent most of the major faults of the area and a large number of suspected faults, including many of northeast trend. Under ideal conditions dip slopes may be recognized, laccoliths outlined, and axial traces drawn for narrow, plunging folds. Use of ERTS-1 imagery will greatly facilitate construction of a needed tectonic map of Montana. From ERTS-1 imagery alone, it was possible to identify up-turned undivided Paleozoic and Mesozoic strata and to map the boundaries of mountain glaciation, intermontane basins, a volcanic field, and an area of granitic rocks. It was also possible to outline clay pans associated with bentonite. However, widespread recognition of gross rock types will be difficult.