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buried in the flank of St. Helens, runs a lava tub ending some miles deep into the side of this volcanoe, ending in a shallow lake. The water is absolutely clear, & cold. It is not divable that I remember, but pehaps there is someone here who will know more about.
Anyone ?
Attachment 4672Ok. here are some links: http://www.oregongrotto.com/mtsthelens.shtml
-FOLLOWING THE ERUPTION:
At the end of the eruption molten lava remaining in the tubes gradually drained away, leaving an open cave. Tubes take a long time to cool, as much as two years. During this cooling breakdown of the walls and ceiling begin to occur. Breakdown is caused by contraction-cracking of the cooling walls and ceilings. Cooling lava shrinks .5% -3%, leaving the cracks seen today in walls, ceilings, and floors. When this takes place, some areas are unsupported, promoting collapse. If collapse extends to the surface, entrances are formed. Not all entrances are collapse related however. Many caves are accessed through skylights. Understanding the process will help in assessing the hazard potential of an entrance.
-In Little Red River Cave, Lake Cave, and Ape Cave, water channels have developed along the contact between the overlying lava and buried paleo soils. Water collecting beneath the lava enters the caves at points where wall linings have collapsed exposing the buried soils. These erosion channels are as much as several hundred feet long. Over the last few years, similar erosional caves have been found along the margins of the Cave Basalt Flow. Some carry water all year and are still being surveyed. The "master" channels which carry most of the water flow to the large springs have not been entered. but are expected to be similar to those already found.-
-Two caves, Little Red River and Lake Cave, contain seasonal streams and lakes at their terminus. Lake Cave only has water during the winter months, but Little Red River Cave has perennial flow, and a semi-permanent lake. The unusual name of this last cave comes from iron oxide stains found in the stream bed.-
Pretty cool. I have been end to end in Ape Cave. Ends in a gravel restriction, no sump there. Awesome cave though, with some epic breakdown piles.