Pumice
VulcanSpirit
Richard & Alison Brunstrom
Wed 18 Sep 2013 02:45
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Vanuatu has eight active volcanos on the surface,
and two underwater. The subsurface ones eject things too, some of which is
pumice - a material which is so light and full of gas bubbles that it floats.
Sometime there are huge rafts of it to sail through covering many hectares at a
time with granule size ranging from a small pea to a cricket ball. Here is some
at sea:
 You'll se that it is olive green here because its
been floating around for a while and its surface is ideal for colonisation by
microscopic algae; newly ejected material is bright grey/white. Curiously it
often forms into lines as you can see, sometimes stretching for miles, caused by
wave action.
When it gets to a beach it is thrown high up onto
the strandline because it floats. Here it is on Tanna, on a white beach (formed
from coral, as opposed to the black beaches formed from volcanic
material):
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