[Proj] Lease block definition

Noel Zinn ndzinn at comcast.net
Mon Sep 1 11:43:54 EDT 2008

The US Outer Continental Shelf (Gulf of Mexico anyway) lease blocks are
defined in NAD27 UTM by zone (so extended coverage per the recent threat is
of no relevance), but in US Survey Feet.  These are federal waters.  State
waters are defines SPCS27.

Google "protraction diagram" and you'll find all the information you'll


-----Original Message-----
From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] On Behalf Of Gerald I. Evenden
Sent: Monday, September 01, 2008 9:31 AM
To: PROJ.4 and general Projections Discussions
Subject: [Proj] Lease block definition

A few weeks ago the item of oil lease blocks came up as an item to be
on extended range TM maps.  My encounter with lease blocks was only as a 
short spectator of someone digitizing the irregular shore boundaries of said

lease blocks.

My understanding is that the lease block boundaries are established in terms

of UTM grid coordinates?  If so, what are the typical side lengths in

My recollection was that one of the reasons for selecting TM for large area 
mapping was because of "facilitating" the plotting of lease blocks.  True, 

Any information related to what has been done or proposed for large region 
mapping with TM would be appreciated.
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist
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