Michael,
See my insertions below.
Lowell G. McManus
Leesville, Louisiana, USA
----- Original Message -----
From: "Michael Kaufman" <mikekaufman79@...>
To: <BoundaryPoint@yahoogroups.com>
Sent: Wednesday, July 14, 2004 10:55 PM
Subject: Re: [BoundaryPoint] world class border arc census was Re: real bjneng
try afoot
> Thanks for these maps:
> For 1. Is the arc the one which faces north with the
> "HUA" of CHIHUAHUA under it and the "S" of TEXAS above
> it? Or the tighter one facing south just to the right
> of it? Or the real wide one facing northeast to the
> right of that?
The arc in this map ( http://tinyurl.com/6msfp ) is the really wide curve. The
others are bends in the natural channel above the beginning of the artificial
channel. There is a short tangent stitch in the artificial channel connecting
the natural channel to the beginning of the wide arc. After making the arc, the
artificial channel enters a very long tangent for over five miles. The former
natural channel is represented on this map by the line that wanders away to the
lower left.
> 2. Arc is the wide curve facing WSW where the other
> stream comes in?
Yes. In this map ( http://tinyurl.com/6u56h ), the arc comes at the end of the
very long tangent mentioned above. The other stream coming in is the old
channel. Notice how it formerly crossed the middle of the arc. After the arc,
there is another short tangent before this segment of the relocation ends as the
river resumes its natural channel.
> 3. Arc faces NNE to the right of "CO" of PRESIDIO CO?
> Or facing S/SSW just below BM 252?
The former. Between arcs 2 and 3, the river has occupied its natural channel
between the cities of Presidio and Ojinaga. Just below the highway bridge, it
enters a tangent artificial channel of approximately 1.25 miles without any
transitional arc. Then, in this map ( http://tinyurl.com/6qgrl ), that tangent
ends with a transitional arc back to the natural channel just above the railroad
bridge. The curve near the benchmark is a natural bend. There are two more
tangent artificial channels in the area below the railroad bridge, but they are
without transitional arcs.
> 4. I remember seeing this before - the 1/4 circle
> facing SE.
Yes. At http://tinyurl.com/5ppgp , you can see the natural channel making a
large meander off to the northwest of this arc. It makes another large meander
to the north of the artificial tangent just below the arc. The relocation here
eliminated both meanders in the river and boundary.
> Also - Is Beaver Island somewhere in this vicinity?
> Is this still an island (if it is in the area, did
> rechannelization have an effect?)?
The "Beaver Island" tract that was transferred to Mexico in the 1970 treaty was
located near Roma-Los Saenz, Texas (about 48 air miles upriver from the fourth
arc above). It was where the word "Tamaulipas" now appears on the map at
http://tinyurl.com/54zcp . It was a rather squarish piece of the USA had been
been orphaned high-and-dry on the southern side of the river by a much earlier
avulsion. This tract and the more contentious Horcón tract, on which part of
the town of Río Rico had unwittingly developed (about 26 air miles downriver
from the fourth arc above) were transferred to Mexico in exchange for the two
meanders gained by the USA at the artificial fourth arc. No channel relocations
were necessary for the transfer of the Beaver Island and Horcón tracts because
both were already on the southern side of the existing river. The island within
the river that is visible on the map belongs to the USA.
> -Mike
>
>
> --- "Lowell G. McManus" <mcmanus71496@...> wrote:
> > The maps from the MXUS Treaty of 1970 showing four
> > arcs are at a scale of
> > 1:20,000 on three long sheets, each about one foot
> > by three feet. They are
> > black-and-white aerial photos with the boundaries
> > through both the old channels
> > (shown by lines between numbered traverse points)
> > and the projected relocated
> > channels plotted onto them.
> >
> > I can scan pertinent portions of these maps for you
> > on request. Meanwhile, here
> > are links to view the arcs on USGS topo maps showing
> > the arcs in the relocated
> > channels.
> >
> > There are three arcs in the Presidio/Ojinaga area:
> > Curve No. 1: http://tinyurl.com/6msfp
> > Curve No. 2: http://tinyurl.com/6u56h
> > Curve No. 3: http://tinyurl.com/6qgrl
> >
> > The fourth is above Hidalgo/Reynosa:
> > http://tinyurl.com/5ppgp
> >
> > Lowell G. McManus
> > Leesville, Louisiana, USA