In appearance, runners look like driblets of lava running down the wall of the cave. They are actually a form of tubular lava stalactite formed along a surface instead of free-hanging. They may also form along the edge of a stalactite. Like tubular lava stalactites, they are formed of cooling segregated lava that is extruded from semi-crystalline wall matrices, propelled by boiling and escaping gases.

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Created: August 4, 2000
Author: Dave Bunnell