MORC monuments
Curly,
The 1889 year sounds right for when the Missouri River Commission (MORC) established the iron pipe/cast iron cap monuments. These are typically over a stone. While different areas of the country might vary, I have found the triangulation stations to be a 4″ inside diameter iron pipe 37″ in length. The 5 3/4″ cast iron cap is bolted to the top and has a raised triangle for the mark and lettered for the agency. This pipe is over a precut square stone 18″ square and 4″ thick. A drill hole is in the center with the letters US above and a triangle below the hole. Depending upon your location, the iron pipes were subject to theft, but the stones are generally still there.
In some cases, USC&GS later came back and removed the MORC cap, filled the pipe with concrete and placed their own brass disk in the top. If you are in areas of rock you might expect to find some sort of pin or dill hole, but most likely there would be some carved letters or triangle nearby.
The MORC did extremely accurate work. If you can find an old MORC mark that has been used by NGS and has a modern position upon it, that will give you the conversion factor for taking the old MORC published position and converting it to modern. Or if you find a MORC mark, get a static position and send it to OPUS. Once you have a comparison you will be able to determine the latitude/longitude of all the others in the area. I have staked out calculated positions by this method and have been dead on when digging down to find the buried stone. A handheld GPS with get you within 10 feet if you don’t mind doing a lot of probing. The old annual reports for the MORC can be found online through Google books and the lat/long positions are listed as well as locations.
The bench marks are similar, but have a cap with a raised circle on top. The stone below them have a drill hole in the center with a very small copper bolt leaded into the hole. The letters US and BM are above and below the hole.
The Fort Rice original position was 46°31’47.13″ 100°41’12.47″
The description says it was on the west end of an east to west ridge.
If you can access this link, go to pages 3774 and 3794.
http://books.google.com/books?id=uJwEAAAAYAAJ&pg=PA3775&lpg=PA3775&dq=Missouri+River+Commission+triangulation+Fort+Rice&source=bl&ots=TtwIX4C_07&sig=s7jw0A7WidPaqNRv_kGgeM7mmzc&hl=en&sa=X&ei=QPBBUNX0OqfLyAHSlYCgCg&ved=0CC0Q6AEwAA#v=onepage&q=Missouri%20River%20Commission%20triangulation%20Fort%20Rice&f=false
Below are some examples I have found for both tri stations and bench marks. Kurt Luebke in Montana is also an excellent source of information of MORC marks in the western states.
Good luck! Let me know what you find.
Triangulation Stations:
http://www.penryfamily.com/surveying/blackbird.html
http://www.penryfamily.com/surveying/ward.html
Bench marks:
http://www.penryfamily.com/surveying/morcbm109-3.html
http://www.penryfamily.com/surveying/morcbm135-1.html
http://www.penryfamily.com/surveying/morcpbm363.html