10-17-2009, 04:44 AM
quote:
Originally posted by Glen
So, it has been stoping through the walls of the vent, it sounds like. I would imagine it takes a lot of pressure for magma to shatter rocks.
I do not think a lot of pressure is involved. the lava pond is at a low level in the vent, the vent fills up with rock from a series of collapses and the stoping is caused mostly by thermal erosion. i.e., the heat and gases that are rising from the magma below serve to weaken the rock and thus melt and fracture it until it is free to fall into the magma below