Benchmarks with Camera Targets

[MSchwiebert]

First off, thanks to all who take care of this site,  I have had a long interest in USGS marks, ever since I took a geography class at Ohio University back in the early 1990's that leaned heavily on how to read a USGS quadrangle.  Anyways, here in Northwest Ohio we have something that I believe to be unique (but am not 100% sure),  that being marks with concrete targets of varying diameters. Almost all were in the McClure photogrammetric test area (most of the markers remain, but the targets have largely been taken out by farming activity in the nearly 50 years since the test area was last used (as far as I know). My question is, were similar things seen elsewhere in the country or are these unique to a couple places in Henry County Ohio?   The photos attached are of one south of the small village of Florida Ohio that was installed in 1963 (there is also one other station within this group that has the remnants of a Camera target) to illustrate what I'm talking about.

Thanks in advance for all replies! 

[foxtrot_xray]

I think I recovered a handful of those McClure ones, either earleir this year or last. I was drawn to the pattern they were laid out on. When looked on a map, they looked neat.

[MSchwiebert]

4 hours ago, foxtrot_xray said:

I think I recovered a handful of those McClure ones, either earleir this year or last. I was drawn to the pattern they were laid out on. When looked on a map, they looked neat.

It is a pretty impressive grouping.  I grew up about 15 minutes from there, and I didn't know anything about the test area until a few years ago.  I've put together a presentation for the county historical society about it that I'm going to put on in a few weeks for them. Unfortunately the years since the area was last used for testing haven't been kind to a few of them like the two photos show.