FIEt.II 1. The structural features — that is, folds — are small in area and in magnitude. The crests of many of the domes and anticlines are not more than 20 or 30 feet high. Ist.drill hole FIG. 12. Diagram showing conditions governing oil accumulations...
Oil Investigations in Illinois in 1914: Area South of the Colmar Oil Field ... - Page 27
by Illinois State Geological Survey, William Clifford Morse - 1915 - 111 pages
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