ABSTRACTLittle information has been published regarding the general geology of the Mackenzie Delta region. On the western side of the Delta bedrock appears to consist largely of Mesozoic sedimentary formations. Coal‐bearing rocks occur some 25 miles northwest of Aklavik and a six‐foot coal seam with almost vertical dip is worked at Moose River Coal Mine. A description of these workings is given.The eastern side of the Delta shows some variety in its geology. Bedrock areas between Campbell Lake and Dolomite Lake are largely formed of dolomite and magnesian limestone. Dolomite, limestone and reddish slaty shale are seen on the north shore of Dolomite Lake and exposures of shaly material are seen on the east bank of the East Channel eight miles south of the entrance channel leading to Dolomite Lake.Between Dolomite Lake and the southern end of the Caribou Hills bedrock is concealed beneath unconsolidated deposits covered by bush and muskeg. The deposits appear to consists largely of silt, clay and gravel, and wrap round and conceal the junction of the Caribou Hills formation with the underlying formations. The undulating and rather formless character of this tract of ground and the relation of the deposits to the bedrock at Dolomite Lake suggest that they are glacial drifts.The Caribou Hills form the most striking feature on the east side of the Delta. They form a steep face or escarpment overlooking the East Channel and rise to their maximum height south of the Reindeer Station. Northwards their altitude gradually diminishes and they terminate against the tundra south‐east and the swamps of the Delta of Tununuk. The rocks consist of soft poorly consolidated silty clay, and fine silt and sand with some pebbly or gravelly sand capping the hills locally. Beds of lignite and very thin layers of ironstone were also seen and, where the lignite has been burned out reddened patches and bands appear on the steep hill slopes. The Caribou Hills formation recalls Tertiary lignite‐bearing formations described from other parts of Northern Canada and Alaska.The bearing of these and other observations upon the history of the Mackenzie Delta is briefly di