Little Sitkin Island

The coast is generally bold, rocky, and precipitous, with a fringe of kelp 200 to 400 yards (180 to 370 m) wide.

Small steam jets and hot springs are in the valley at the head of William Cove on the northwest of the island.

A summit crater caps the youngest cone, about 3 miles (4.8 km) in diameter at the base.

The active stratovolcano on Little Sitkin Island occurs within the eroded remnants of a nested double caldera of probable late Pleistocene age.

The caldera formed at the site of a large stratovolcano, the remnants of which are the oldest rocks exposed on the island.

Two relatively recent aa flows have well-developed levees; one originated from the breached central crater of Little Sitkin volcano, and the other from a fissure along the western trace of the Caldera One boundary fault.