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Aeromagnetic map of the Nabesna Quadrangle, Alaska Aeromagnetic map of the Nabesna Quadrangle, Alaska

The aeromagnetic map (sheet 1) of the Nabesna quadrangle was prepared in 1971 and subsequently released by the State of Alaska as an open-file map (Alaska Div. Geol. and Geophysics, 1973). The data were collected along north-south traverses spaced at 1.6 km intervals at an altitude of 330 m (1000 ft) above the ground. Compilation was originally in the form of 30' x 15' quadrangles at a...

Bedrock topography of northeast Iowa Bedrock topography of northeast Iowa

The bedrock in Iowa (Hershey, 1969) is generally overlain by deposits of glacial drift and alluvium, which range in thickness from less than 1 foot (0.3 m) to more than 400 ft (18 m), respectively. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses when were developed during a long period of preglacial erosion and during shorter, but...
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