Geophysical observations were carried out in conjunction with a geological survey of the Peake Denison Ranges during the winter of 1953. To the east of the main range geophysical evidence would indicate a gradual shelving of bedrock, deepening to the east. On the western side of the range and some miles west of the edge of the range, there is generally a sudden decrease westwards in gravity values indicating a more sudden deepening of basement rock. A fault of considerable throw is revealed to the east of Mount Dutton. Further, a traverse run east and west of Anna Creek station indicates a continuation of a shallow basement ridge southwards.