Wilmot Hyde Bradley, 80, a research geologist and retired division chief of the U.S. Geological Survey, died April 12 at home in Milbridge, Maine, after a stroke.

He was an authority on military geology, oceanic geology, and oil shale,formation in the western United States.

During World War ii, Dr. Bradley helped organize and then served as chief of the survey's military geology unit. Provided basic for america combat forces. Such informatiom would help soldiers and Marines determine what type of landing equipment could cross a particular beach. where they would most likely locate drinking water on an island, where best to build an air-strip, how deeply trenches could be dug without hitting water or rock, and other factors in military operations.

Following the war, Dr. Bradley was chief geologist of the survey's geologic division, directing the work of government earth scientists.

From 1959 untilhe retired 10 years later, he did research on stratigraphy, the study of the nature anddistribution of stratified rocks in the earth's crust, and on sedimentation.

He helped pioneer the study of the history of the earth's crust and the geological composition of the ocean floor and its sediments through the use of drill core samples made in the North Atlantic.

Dr. Bradley was born in Westville, Conn, and earned a bachelor's degree at Yale University. He joined the Geological Survey in 1922 and held several posts in the western United States, where he studied oil shale deposits. He returned to Yale and received a doctoral degree in geology in 1927.

He was the author of more than 70 technical works. His professional awards included the Washington Academy of Sciences' Awardof Merit in 1940, the Interior Department's Distinguished Service Award in 1958, and the Penrose Medal of the Geological Society of America in 1972.

He was president of the Geological Society of Washington in 1946 and the Geological Society of America in 1965. He also belonged to the American Philosophical Society, the American Society of Limnology and Oceanography, and the American Association of Petroleum Geologists.

Survivors include his wife, Catrina, of the home; two daughters, Ann Strong, of Oylmpia, Wash.,and Penny Shavit of Israel, and seven grandchilren. CAPTION: Picture, WILMOT H. BRADLEY