Cyclic deposits containing hummocky cross-stratification occur in the upper part of the Cape Sebastian Sandstone, a shallow marine transgressive sandstone of Late Cretaceous age on the southern Oregon coast. The cycles consist, where complete, of a lower hummocky cross-stratified sandstone, a middle planar- and ripple-bedded sandstone with a shale bed in its middle part, and an upper bioturbated sandstone. Depositional conditions are interpreted from the characteristics of these cycles. -from Authors