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Illinois-Wisconsin, Belvidere quadrangle : topography

1918. Geological Survey (U.S.). Surveyed in 1917.;Surveyed in cooperation with the War Department and the State of Illinois.";Relief shown by contours and spot heights.;1 map, col...

Illinois-Wisconsin (Winnebago County), Rockford quadrangle : topography

1918. Geological Survey (U.S.). Contour interval 20 feet.;"Surveyed in 1917.";"Surveyed in cooperation with the War Department and the State of Illinois.";Relief shown by contours...