In Joel's initial post on this matter, he mentioned VOLCANIC rocks
cooling. I think the response I posted to that a fair one. However,
this post of Joel leaves out the qualifier "volcanic" and I find this
significant enough to comment on further. There are PLUTONIC rocks
to consider, and here there is a much more serious challenge to short
timescales. I've noted Glenn's response, which develops the point in
the context of plutonic rocks. I would like to argue that the
principles given in my post on volcanic cooling still apply - but the
issues are much more complex. I'll try to respond in more detail to
Glenn's post next week.
Best wishes,