Karl Stefansson, 63, who was a geologist with the U.S. Geological Survey for more than 20 years, died of a heart ailment Dec. 20 at Prince George's General Hospital.

Dr. Stefansson was born in Iceland, came to this country at the age of 16 and earned bachelor's and doctorate degrees in geology at Johns Hopkins University.

He worked for the Geological Survey from 1943 to 1949 on Alaska's North Slope as part of the team that discovered oil there. Dr. Stefansson received a presidential commendation for this work.

After working in and earned bachelor's and doctorate degrees in geology at Johns Hopkins University.

He worked for the Geological Survey from 1943 to 1949 on Alaska's North Slope as part of the team that discovereed oil there. Dr. Stefansson received a presidential commendation for this work.

After working in private industry for a number of years, he returned to the Survey in 1961, where among other things he was in charge of the Survey's "Rock Library" near Beltsville. He also did a geological survey of Maryland's Eastern Shore.

Dr. Stefansson is survived by his wife, Ellen C., and two daughters, Karen and Kelcy, all of the home in Bowie; two other daughters, Karla Chapman, of Laurel, and Kathleen Green, of Davidsonville, Md.; two sisters, Valgerdur Bain, of Pikesville, Md., and Solveig Creswell, of Littleton, Col.; and two brothers, Stefan, of Pikesville, Md., and Ragnar, of Iceland.

The family suggests that expressions of sympathy may be in the form of contributions to the American Heart Association.