Authigenic clays in eight sandstone samples from the North Sabine H-49 well in the Sverdrup Basin, N.W.T., have been studied by X-ray diffraction and scanning electron microscopy. The following sequence of authigenic minerals was observed with increasing burial depth: quartz–kaolinite, illitic 2:1 layer silicates, and chlorite. It is suggested that the formation of authigenic clays in sandstones can be considered in the context and as a product of catagenesis of adjacent shales. Upon burial, water is released from the shales by compaction, clay dehydration, and clay destruction. Continuing compaction carries the products of clay transformation to the sandstones where they precipitate to form authigenic clays. The nature of the authigenic clay is directly related to the physico-chemical conditions existing at various depths.