Re: exploding rocks
Lynn Whited (whited@ASTROSUN.TN.CORNELL.EDU)
Sun, 12 Nov 1995 08:33:35 -0500
On Sun, 12 Nov 1995, Michael F. Bowman wrote:
> Two things not to do to keep warm on a frigid campout:
> 1. Don't pick the wrong type of rock. Back in Indiana, we had a lot of
> rocks that were mostly compressed sediment and full of water. A couple
> of bright lads picked these and tossed them on the fire to warm and then
> wandered over to see what was going on at the next patrol site.
> Ckkkrrraaack! Kabloom! The rocks started exploding. The water became
> super pressurized steam and the rock was basically weak structurally.
> No one was hurt but a couple of tents looked liked they had be fragged by
> a grenade from the flying shards. Any geologists that can help out as to
> what these rocks were or ones to avoid?
Not a Geologist, but experience with exploding rocks...they were
probabaly shale...Here in the Finger Lakes Region of NY it is very
prevalent. Shale is usually flatter than most rocks, and has distinct
layers, that break apart easily. The first thing we teach our Girl
Scouts is to check the fire ring for any stray shale. On one camp out
with Juniors (4th & 5th graders) they diligently checked the fire circle
and cleaned out all of the shale. But then when it came time to cook,
one of the girls brought over a LARGE FLAT stone to use as a 'table' and
placed it next to the fire. Luckily one of the girls realised it was
shale and removed it quickly. Every once in a while small shale stones
are missed and the result is a fire that sounds like pop corn popping
into a mcirophone.
Lynn Whited | Junior Troop 401
firstname.lastname@example.org | Junior Program Consultant
Cornell University | Canoe Instructor / Leader
315-787-2281 | Seven Lakes Girl Scout Council
Terry Howerton Sakima Group, Inc. SCOUTER Magazine Kansas City