Mesozoic sedimentary rocks in the Kandik basin are subdivided provisionally into four units. The oldest, unit A, rests unconformably on the Tahkandit Limestone of Permian age. It consists mainly of carbonaceous argillite but includes some limestone, oil shale, and quartz arenite. This unit is about 5,000 ft. thick and ranges in age from Middle Triassic (Ladinian) at its base to Early Cretaceous (Valanginian) at its top. Conformably overlying unit A is unit B, a massive quartz arenite with minor interbeds of argillite and chert-pebble conglomerate. Unit B is less than 100 ft. thick south of the Yukon River but northward it thickens to about 1,000 ft. or more in the headwaters of the Black River. Pelecypods of Valanginian age have been found in the quartz arenite at several widely spaced localities. Unit B grades conformably upward into unit C, a rhythmically bedded quartz arenite and argillite, at least 5,000 ft. thick, that forms a substantial part of the Kandik Formation (Lower Cretaceous) at its type locality. Pelecypods of Valanginian age occur in the lower part of unit C. Unit D consists of chert-pebble conglomerate, sandstone, siltstone, and argillite, all of the graywacke type. It rests conformably on unit C in the vicinity of the Yukon

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River, but apparently rests unconformably on units B and A and on rocks of Paleozoic age near Indian Grave Creek. Unit D is several thousand feet thick and is provisionally correlated with non-marine clastic rocks of Early Cretaceous (Albian) age near Eagle, Alaska.

The oil shale within unit A is a potential source bed for petroleum, but none of the Mesozoic rocks cropping out in the Kandik basin seem to have enough porosity to make them potential reservoirs. Although the oil possibilities of the Mesozoic rocks are not encouraging, some of the Paleozoic rocks contain oil and therefore deserve further investigation.

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