Like flowing water, a lava stream flowing underground can form a falls if the terrain on which the tube forms is suddenly steeper. Such falls can range from a few feet to over 60' high, requiring rope to negotiate. Usually the falls form in the lowest levels of lava tubes, rather than forming where a flow meets a window and drops through to a lower level.
Many of the erosive features associated with waterfalls also occur with lavafalls, with the hot lava thermally eroding into bedrock and backcutting. As the lavafall retreats upstream, it leaves a high-ceiling chamber downstream of it. Larger falls often have lava lakes formed at the base, where turbulence creates a deeper basin or plunge pool. Plunge pools can be quite deep, especially if the falls was not back-cutting. Studies indicate that their depth can be as much as twice the pool width.
Turbulence also results in passage widening at the base of the falls, typically with breakdown of the undercut walls above the growing plunge pool.



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Created: August 4, 2000
Author: Dave Bunnell