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Geologic Mapping From Aerial Photography In The Boston Mountains, Northwestern Arkansas, Mikel R. Shinn

Journal of the Arkansas Academy of Science

Aerial photography has been employed to map stratigraphic and structural features in the Boston Mountains of Washington and Crawford Counties, Arkansas. Exposures of resistant stratigraphic units within the lower Atoka Formation were delineated on a series of large scale aerial photographs over an area of about 150 square miles. With the aid of a Bausch & Lomb Zoom Transfer Scope, the positions of the units were subsequently transferred to 1: 24,000 scale topographic base maps. The presense of east trending anticlines and synclines and a series of low displacement normal faults is reflected by either gradual or abrupt changes in …

Stratigraphy Of Chugwater Group (Triassic) East Side Of Bighorn Mountains, Wyoming And Montana, Robert C. Mclellan

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

The Chugwater Group (Triassic), on the east side of the Bighorn Mountains of Wyoming and Montana, forms a narrow outcrop band of hogbacks. Four redbed formations are included in the Chugwater. From base to top they are: 1) Red Peak, 2) Crow Mountain, 3) Jelm, and 4) Popo Agie. The Chugwater is disconformably underlain by t];ie Goose Egg Formation (Permian) and unconformably overlain, from south to north, by the Sundance, Gypsum Spring, and Piper Formations of Jurassic Age.

The rocks of the Chugwater, in order of abundance, are: siltstone, sandstone, claystone, conglomerate, limestone, dolomite, and gypsum. Binocular microscope studies were …