Lava Lake
When lava ponds up in a passage it cools to form a smooth-surfaced lake. Typically the ponding occurs in plunge pool basins eroded beneath lavafalls, as seen in the first photo. They may also occur when flows have been backed up by constrictions downstream of the flow due to passage collapse, which is probably what formed the now-drained lake in the second photo. Here the center of the lake’s surface collapsed, leaving broad shelves along each side.
AUTHOR: Dave Bunnell
Lava Lake 1 - Dave Bunnell
Large lake beneath a drop in Hawaii's Kazumura Cave System
Lava Lake 2 - Dave Bunnell
Thin shelves are the remnant of a lava lake whose surface cooled, then drained beneath, then collapsed in the center.
