--- In
BoundaryPoint@yahoogroups.com, "Lowell G. McManus"
<mcmanus71496@m...> wrote:
> Okay, Adam (plus Mike and anyone else paying attention), I'm back.
I am
> inserting my comments below.
>
> > A while ago somebody (it might have been acroorca2002) posted
about a
> > trip to visit the northernmost point in mexico, which I guess
under
> > our notation would be something like mxn or mxus2azcabc. Anyway, I
> > was planning a visit out the that area either this coming Friday
or
> > Saturday, and was wondering if anyone had any hints on the best
ways
> > to approach the point. I guess Lowell would have the goods on
where
> > exactly in the Colorado River the tripoint is, since he's our
> > resident expert on the usmx treaty.
>
> The current 1970 MXUS treaty says that the international boundary
in both the
> Colorado River and the Rio Grande "shall run along the middle of
the channel
> occupied by normal flow and, where either of the rivers has two or
more
> channels, along the middle of the channel which in normal flows has
the greater
> or greatest average width over its length." Note that the operative
> measurements exclude depth, which is generally in short supply in
these rivers.
>
> As Mike has pointed out, the AZCA boundary runs "down the middle
of the channel
> of said [Colorado] river." The two descriptions are essentially in
agreement.
> Since this river is hardly navigable, I would tend to discount the
thalweg and
> lean toward the median line for each boundary.
wait
you just indicated mxus follows the middle of the normally widest
channel
this is not the same thing as the middle of the full channel or bed
between the veggies
& that is an additional reason
on top of those just given in my answer to adam
why i think your leap to the median line may be questionable
but lets at least wait for adams report to see how much of a
difference there may be between the 2 positions
before we get too excited anyway
for i know he will be doing great to even get close enough to have to
settle this question
The best practical estimation
> of this would probably be half of the distance between the
vegetation lines on
> the respective banks.
>
> > I suppose another historical tripoint I could pick up would be the
> > historical tripoint between California, New Mexico Territory, and
> > Mexico before the Gadsden Purchase was made. That would be where
the
> > Gila River flows into the Colorado, on the north side of Yuma,
right?
> > Lowell, do you have any idea whether that tripoint would be in the
> > river midpoint, the thalweg, one of the banks, or what?
>
> The juncture of the two mentioned river would be the ghost
tripoint; however,
> both rivers show evidence of having been highly braided and
meandering
> streamcourses in their relevant reaches. I doubt that it would be
humanly
> possible to ascertain the precise point. In fact, the current AZCA
boundary has
> been reduced to a series of stepped surveyed lines across a former
meander about
> four miles in diameter called "The Island" at the mouth(s) of the
Gila. I
> assume that this was done (apparently post-Van Zandt) as the only
practical
> solution by agreement between the states and the consent of the
Congress, but I
> have not researched the particulars. Clearly, if the Gadsden
Purchase had not
> occurred, demarcation of the MXUS boundary through this same area
just northeast
> of Yuma would have required an innovative solution.
>
> Lowell G. McManus
> Leesville, Louisiana, USA