Abstract

Side-looking airborne radar is a versatile and particularly useful tool for the detection and mapping of lineaments and other geologic structural features. The utility of radar is derived primarily from its ability to (1) illuminate the earth’s surface with controlled low-oblique angles from any desired azimuth, and (2) obtain imagery when desired regardless of the time of day or most weather conditions. Lineaments detected on radar imagery result from both topographic relief and tonal anomalies. The Corps of Engineers is applying radar to a variety of engineering and geologic investigations in connection with planning, design and construction of civil works projects and land-use planning studies.

During the course of these investigations, radar imagery was taken of terrain having markedly different geologic settings, i.e., exposed Precambrian, Precambrian covered by thick flat-lying sediments, crumpled sedimentary and volcanic rocks with no Precambrian basement, and tightly folded metamorphics with igneous intrusives. Interpretation of the imagery revealed that two or more, roughly orthogonal, lineament trends persist with little or no apparent regard for local geologic structure. Evidence is also present to suggest that most regional lineaments must be near vertical features resulting from both compressional and vertical forces, the latter being most prevalent.