Stepovak Bay Group

The Stepovak Bay Group is a chain of four cones, extending over a distance of 18 km, just SW of Kupreanof volcano. Stepovak Bay 2 is a cinder cone with a Holocene andesitic lava flow extending initially to the NE, then SE. The Stepovak Bay 3 cinder cone has a thick Holocene lava flow that originated from an ice-filled 300-m-wide crater and entered the same valley as the lava flow from Stepovak Bay 2 (Wilson, 1989); however, Wilson (in Wood and Kienle, 1990) noted uncertainty about this being Holocene activity. Stepovak Bay 4 is a small stratovolcano with Holocene debris flows or block-and-ash flows, and a fumarole has been observed. Stepovak Bay 1, the southwesternmost of the chain is Pleistocene, with K-Ar dates of about 0.53 and 0.4 million years (Wilson, 1989).