just realized
the dry segment of caus on seaway island could indeed have
been caused either by avulsion or accretion
since it was after all not part of a true thalweg boundary
but of a zigzagging chain of metes & bounds & turnpoints
which approximated to that thalweg at one time
but which extends in the present case from turnpoint 174
situated just above seaway island as seen here
http://test.topozone.com/map.asp?z=17&n=4710111&e=362910
&s=48&layer=DRG25&size=l
all the way to turnpoint 173
not visible here because it is actually 15 miles away
almost clear across the lake in fact
& no amount of avulsion or accretion will ever change that line
nor its continuations in both directions thru any of these other
fixed turnpoints in the same series
http://www.internationalboundarycommission.org/coordinates/S
ECT-K-83.txt
nor any others anywhere else on caus for that matter
for i confess i have been unable to find any exceptions anywhere
on caus to this distinctive wet turnpoint regime
however
even after all that revision of my earlier surmise
i would still guess the cause of the channel change was avulsive
rather than accretive
given that there is an artificial shipping lane on either side of it
another & bigger thing i noticed tho
thanx to this impromptu but comprehensive excursion
is that caus is actually entirely geodetic from end to end
unlike mxus & most others
not a stitch of caus wet or dry has been left to chance
--- In
BoundaryPoint@yahoogroups.com, "acroorca2002"
<orc@o...> wrote:
> a few self corrections & additions
>
> in the caus or rather gbus treaties of 1782 & 1814
> the terminology of choice is simply
> the river
> or
> the middle of the river
> or
> the middle of the lake
> wherever a boundary river or lake is mentioned
> except
> coincidentally
> for the very area we are talking about
>
> here the 1814 treaty says the boundary runs
> thru the middle of lake saint clair
> in a direction to enter that mouth or channel of the river saint
clair
> which is usually denominated the old ship channel
> thence along the middle of said channel
> between squirrel island on the southeast & hersons island on
> the northwest
> etc etc
>
> this passage is interesting even if only tantalizing
> both because it marks the earliest usage of the term
> middle of the ship channel
> in any caus text i can find
> despite meaning not necessarily the same thing as thalweg
> & also because it evidently predates the naming &or the actual
> alluvial accretions of bassett & seaway islands
> or maybe predates only the openings of bassett channel & the
> saint clair cutoff within an originally much larger squirrel island
> embracing all the above modern features
> for the meaning of this also is unclear
>
> but anyway it wasnt until the treaty of 1842
> pursuant to the failed arbitration of the king of the netherlands
in
> 1829 which had introduced the idea of thalweg for the first time
> that the standard gbus or caus terminology was changed to
> the middle of the main channel of the river
> & now much more clearly tending to mean thalweg
> even if still possibly somewhat ambiguous
>
> however a specific & clear elaboration of the thalweg or the
> middle of the shipping channel or something else was soon
> sidestepped in most places by the adoption of a system of
> defined courses & distances between angle points
>
> the result is that the little dry stitch of caus on seaway island is
> not unique because the boundary line at many of the narrows
&
> canoe portages in the boundary waters is defined by just such
a
> series of courses & distances & angle points
>
http://test.topozone.com/map.asp?z=15&n=5330194&e=686028
> &s=24&layer=DRG25&size=m
> wherein the zigzagging metes & bounds are probably eluded
at
> times by the narrow & also shifty streamlets that originally
> defined the boundary in such places
>
> but even without such unknowable minor lapses
> & a swamp portage i cant evaluate
>
http://test.topozone.com/map.asp?z=15&n=5338958&e=644861
> &s=24&layer=DRG25
> & another possible delta avulsion formation i also cant be sure
> about
>
http://test.topozone.com/map.asp?z=15&n=5374350&e=457541
> &s=48&layer=DRG25
> there is an undeniable height of land portage i did forget about
>
http://test.topozone.com/map.asp?lat=48.0974&lon=-90.5622&s
> =24&layer=DRG25&size=l
>
> so in a nutshell the corrections are
> the dry stitch on seaway island is not unique after all but
merely
> quite rare on the waterway sectors of caus
>
> & caus does not by & large follow thalwegs the way mxus &
most
> other river borders do
>
> --- In BoundaryPoint@yahoogroups.com, "acroorca2002"
> <orc@o...> wrote:
> > --- In BoundaryPoint@yahoogroups.com, Tom Sanders
> > <hilversum96@y...> wrote:
> > > Now you've stirred my curiosity, :)
> >
> > great
> > i love the stuff
> > & you see how most prefer to fluff & duff
> >
> > more below
> >
> > > I based my low water theory on living on Lake Huron
> > > and watching the high water levels fluctuate from year
> > > to year. Dry winters usually mean siginificantly lower
> > > water levels on all the Great Lakes during the next
> > > summer. But the ups and downs always average out in
> > > the short term.
> > >
> > > However, my neighbors tell me that our beach wasn't
> > > here when they moved here in 1969. Their boathouse,
> > > which is now separated by a hundred or so feet of
> > > beach from the shoreline, was originally right on the
> > > water. So the high water mark has retreated that far
> > > over 34 years.
> > >
> > > Place that scenario in the St. Clair flats, I
> > > reasoned, and it's possible that sandbars could become
> > > permanently exposed, and islands could increase in
> > > size over 30 or 40 years.
> >
> > wonderful
> > i am with you loud & clear on all the above
> >
> > > I'm also guessing that the shipping channel is the
> > > same one used before the Seaway by Great Lakes
> > > freighters, and dredged to accomodate ocean-going
> > > ships when the Seaway was built. Also that the border
> > > always follows the main shipping channel.
> >
> > ok i would second guess on both of these guesses tho
> > as i think you also do below
> >
> > i believe the border from lake of the woods to akwesasne did
> all
> > begin by following the main shipping channel or thalweg
> > but clearly the dry boundary on seaway island is exceptional
if
> > not unique along this vast reach of caus in no longer
following
> > any channel
> >
> > & such a desertion of the border by the channel could only
> have
> > occurred suddenly & not gradually
> > like say during a huge spring flood
> > or if the main shipping channel was ever rerouted by design
> >
> > If the
> > > current channel had been cut through Seaway Island in
> > > 1958, and the border re-aligned to follow it, we'd
> > > know about it, for lack of better words.
> > >
> > > It's possible that the Walpole Island seaway project
> > > involved cutting a new water path through Bassett
> > > Island (the "cutoff" on the topo map). That would have
> > > created a new island, appropriately named "Seaway."
> >
> > yes this is exactly my guess
> > perhaps circa 1959
> > & it would explain when & why the border didnt come along
for
> > the ride to the new cutoff
> > but not yet when or why seaway island grew into the usa
> >
> > my guess for that is partly the lowering water levels you
> describe
> > but especially the dredging of the saint clair flats canal
> > date unknown but possibly circa 1959 too tho maybe much
> later
> > & which appears to have included a deliberate new riprap or
> > embankment plus landfill additions to seaway island behind
it
> > including the complete backfilling of part of the original
> > navigation channel along the caus line
> >
> > hence this so precious & probably unique little dry stitch
along
> > an otherwise completely wet seam
> >
> > > (Thanks for those Walpole Island links, BTW. That's
> > > always been a favorite place of mine.)
> > >
> > > You'd really need to compare the current topo with a
> > > pre-1958 large scale map of Lake St. Clair. None of my
> > > old large-scale SE MI road maps cover Harsens Island
> > > or the St. Clair flats. (The current AAA, American
> > > Auto Club, SE MI map, 1 inch to 3.5 miles but not
> > > exactly a definitive reference for shoreline
> > > alignments, does, but doesn't show the sliver of
> > > Seaway Island extending into the USA.)
> > >
> > > Or it might be the time for a one-day border
> > > expedition to the far southern tip of Harsen's Island,
> > > to see what can be seen.
> > >
> > > Either way, as with the knothole in the board fence
> > > out by the nudist camp, I'll be looking into it, :)
> >
> > bravo
> > & we will be with you looking over it