The December 2010 issue of National Geographic Magazine has a 12-page
article on bats and the White Nose Syndrome threat with several bat and
cave photos.
Also, the Deadly Descent caving series on Discovery Channel that was
supposed to start on Thanksgiving evening has disappeared from their
texascavers Digest 18 Nov 2010 16:44:10 - Issue 1195
Topics (messages 16527 through 16531):
Re: GPS Datum
16527 by: caverarch.aol.com
16529 by: Mark Minton
16530 by: George Veni
16531 by: caverarch.aol.com
Re: Mexican officials blame cave swamp gas for hotel
I didn't send this to Texascavers on the first round because it wasn't on the
reply list, so I hope that Terry doesn't mind my forwarding this on. I've
chosen to do so because of George's comment that many cavers don't carry topo
maps in the field. One of the things I chose to mention below is
Actually, there is a preferred datum used by surveyors: WGS 84. Topo maps
are set to NAD 27, which was established in 1927 based on a single geodetic
point roughly in the middle of the lower 48 US states. For practical
purposes, it is the best datum to use when in the field trying to find your
way
There is no 'preferred' datum. You need to use the datum
that corresponds to the maps or other coordinate systems you are
interfacing with. The only time you would have to pick a preferred
datum would be if you were creating a new map or area survey and
needed a way to reference it.
I would find it hard to believe that enough swamp gas could do this. However,
a leaking gasoline tank at or near the hotel or a broken natural gas line could
do it.
I thought the quotes from George V. and Lee F. were good. Someone actually did
some research to find these two.
Geary
From: j
