Geologic Interpretation of Magnetic Map, Washington County, lowa

In 1963, ground measurements of the vertical component of the earth\u27s magnetic field were made in Washington County, Iowa. The magnetic variations are attributed to differences in the lithology and configuration of the Precambrian crystalline basement complex about which no direct geologic information is available. Although a unique interpretation of the magnetic data is impossible owing to the limited geologic control, it is proposed that the basement complex is at a depth of 2,600 to 5,000 feet, may be cut by a northeasterly trending fault occurring near the city of Washington, and exhibits topographic relief which controls the formation of domes and basins in the overlying Paleozoic sedimentary rocks. If the proposed interpretation is valid, it should be possible to locate Paleozoic structures in adjacent counties by magnetic mapping