Ojakangas, Richard W. The earth, past & present / Richard W. Ojakangas, David G. Darby - New York : McGraw-Hill, c1976 - x, 260 p. : ill., plates ; 23 cm. - McGraw-Hill earth science paperback series . Includes index ISBN: 0070476764 : USD 5.95 Subjects--Topical Terms: GeologyEarth Dewey Class. No.: 550