Not a conventional benchmark...

[ArtMan]

... so what is it?

 

Small bronze plaque set atop a square concrete post about 3 feet high in Pere Marquette State Park outside Grafton, Illinois.

 

 

I didn't measure it, but the plaque is about 2 x 3 inches, and reads as follows (the best I can transcribe it):

 

WATER

2.5' —>

STA. 11 — 19.8

< 8° 49 RT

 

There may be a vertical line after the arrow on the second line, though there is no obvious water two and a half feet approximately north from the post (unless it's an underground pipe).

 

The symbol on the last line (before the '8') looks like it might be the geometry symbol for an angle.

 

The location is near an lookout platform overlooking the Illinois River at approximate coordinates 38 58 43.6, -90 32 29.1

 

Thanks for any ideas....

 

-ArtMan-

[Bill93]

I thought about meander lines from the land survey, but then I pulled up the topo and saw that it is pretty far above the water so that wouldn't be it.

 

I'd guess it is a traverse point in a survey of some kind. I think the dash is really a plus made with two chisel marks, to read Station 11 (hundred feet) + 19.8 (feet) from the starting point. The traverse would bend 8 degrees 49 minutes to the right at that point (when moving in the forward direction.

 

The topo has a triangle symbol about 1100 ft SW of there and a water filtration plant about 1100 ft SE.

 

But that's all a guess.

Edited January 2, 2012 by Bill93

[southpawaz]

My guess is that it marks a 2.5 foot offset to an angle point in an underground water line.

Edited January 2, 2012 by southpawaz