went ashore before the invasions with boring tools to find out if the old reports were correct, and special equipment was developed to overcome the problem. For the invasion, large scale maps, in three editions, of the Normandy beach conditions of 1:5,000 were printed in great secrecy, with each map numbered for controlled use. Few copies of these maps survived the war. Other maps were prepared to show the best areas suitable for building airfields, and of water supply locations. Origin of Balloon Bombs The Military Geology Unit was key in determining the origin of Japanese Fu-Go balloon bombs. Working with Colonel Sidman Poole of US Army Intelligence, the researchers of the Military Geological Unit began microscopic and chemical examination of the sand from the sandbags to determine types and distribution of diatoms and other microscopic sea creatures, and its mineral composition. The sand could not be coming from American beaches, nor from the mid-Pacific. It had to be coming from Japan. Ultimately the geologists determined the precise beaches in Japan the sand had been taken from. By this time, it was mostly irrelevant, since by early spring the balloon offensive was almost over. Planetary Geology A number of reports were produced by the Military Geologists covering the moon, including the first photogeologic map of the near side. Permafrost Under the aegis of the Military Geology Unit, some of the earliest research and documentation on permafrost was published in English. Research on the topic had only been previously published in Russian. References Bibliography Bevan, Arthur. 1944. "Military Geology." Scientific Monthly. Volume 62, 1946. Pages 466-468. Bonham, Selma and Leith, William (William Stanley), 1997, Reports and maps of the Military Geology Unit, 1942-1975. Reston, Va.: U.S. Geological Survey. 116 leaves. U.S. Geological Survey open-file report; 97-175. Geological Survey (U.S.). Military Geology Branch. 1945?, The Military Geology Unit: U. S. Geological Survey and Corps of Engineers, U. S. Army. "Prepared by members of the staff of the Military Geology Unit for distribution at the Pittsburgh (1945) meeting of The Geological Society of America." No place of publication given: The Geological Society of America. 22 pages. Hadden, Robert Lee. 2003. "The Heringen Collection of the US Geological Survey Library." Session No. 94, History of Geology (GSA History of Geology Division, History of Earth Science Society [HESS]). November 3, 2003. Geological Society of America Abstracts with Programs, Vol. 35, No. 6, September 2003, p.