Lava flows line the steep walls of a pit crater on Santa Cruz island. Note the person standing on the rim at the right for scale. Pit craters are formed by collapse following the withdrawal of magma along a rift zone. They differ from other craters in that their rims lack a mantle of explosive debris. In some cases, vertical-walled pit craters can be hundreds of meters deep.

Photo by Lee Siebert, 1978 (Smithsonian Institution).

This image is made available under the Public Domain Dedication CC0 license, but proper attribution is appreciated.

Santa Cruz