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Chiseled Squares

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I would say definitely not. That is a saw mark in the concrete. What you are looking for could be very hard to see, as it may have weathered away or blended in with the concrete. It will be an actual square or rectangle shape, chiseled into the concrete.


This one was easy to see: KW0758


Here is a harder one: KW0651


From the looks of the concrete your bridge may have been replaced. Chiseled squares have not been used (much) recently.



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I'll have to agree with mloser that your picture is most likely of a saw cut and not the chiseled square you were (are) looking for. As mloser said, you will be looking an actual square, about 1"-2" across, chiseled into the top of the concrete abutment. Chiseled squares are most often found at the edge of the concrete surface, not in the middle, with the edge of the concrete being one of the sides of the square (only three sides of the square may be chiseled).


Chiseled squares are commonly used as temporary benchmarks by surveyors performing elevation surveys or construction surveys (or both). A chisel and hammer can be easily carried and used many times, and the chiseled squares can be every bit as accurate (vertically) as a 3" brass disk. Brass disks may last longer though, and they are much easier to locate, particularly if the concrete is weathered. While they are not commonly used (any more) as NGS benchmarks, there are many areas and municipalities that frequently use them. As a matter of fact, the bulk of the city benchmarks for Fresno, California are chiseled squares.


- Kewaneh

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I visited one today that I think others will find interesting--and I would appreciate a few more opinions. JV3222 lies in the wall of a dam along the Potomac River. I've not seen chiseled squares--and the photos listed above were relatively fresh in my mind--so the depression that I identified as the square was not done so with much confidence. It was in the right vicinity, but I didn't have anything like a tape measure with me.


As a matter of fact, I fretted all the way home that I hadn't found the mark. But I figured the "BM" and "USCS" were positive signs. It was when I was logging the find that I gave myself a dope-slap when I realized that the mysterious "C" chisled into the stone was the designation.


I'll plead that the presence of my family--decidedly *not* into figuring out anything to do with benchmarking--clouded my deductive reasoning abilities.


Seriously, though, would others agree (or not) that the place I photographed could represent a chiseled square in this instance?

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Looks to me it does.


But it would appear that it is in poor condition. That hole is not supposed to be there, the concrete is spalling. It is probably still useful though as I am sure a survey would find a way to use the mark, placing a level rod on top of the hole might only mean a different of a few mm's.


Spalling - When poured concrete chips, fragments or breaks apart.

Edited by elcamino
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My theory -


1. A chiseled square was made in that spot between the B. and the M.


2. At some later time, a surveyor punched the center of the square to make a centerpoint.


3. The rock-fracturing incidents #1 and #2 combined with a couple hundred freezes and floods made the squarish hole with center indentation you see now.


For comparison, here is a contemporary mark from the same county. The chiseled square is between the B. and the M.

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