Upwelled Lava

Lava flows may surge or back up due to a constriction downflow and flow out of windows or entrances. Often this lava leaves a lining deposit around the edge as evidence of its passing, and may even deposit lava balls that were being carried along, around the edges of the entrance or window. A different sort of upwelling can occur from floors of tubes when segregations boil out of the semi-solid floor. Sometimes these resemble miniature volcanoes as in photo 1.

In the second photo, lava has upwelled from a lower level through a window and sealed the window shut as it cooled.

AUTHOR: Dave Bunnell