Marine terraces of the western Aleutian Islands, Alaska

The islands of the Rat Islands group, which includes Amchitka Island, have active sea cliffs, well-developed intertidal platforms, and a prominent submarine platform at -100 m. These features have not been disturbed by tectonic activity for the past 17,000 years. The islands of the Delarof Islands group, located east of Amchitka Pass, have inactive sea cliffs and emergent low terraces that indicate relatively recent uplift, possibly as much as 4 m. Higher and older marine terraces on the islands of both groups cannot be correlated, and some tectonic adjustment between the island groups is suggested.