USGS
Triangulation Station
"STATE LINE"

1893

Jerry Penry
May 12, 2019

This monument was the furthest south of the points within the 1893 Black Hills triangulation network and was most likely placed at this location to tie into the large quartzite stone milepost markers that are located on the Nebraska/South Dakota state line. It was apparently not intended to be permanent since the monument was described as being just a nail in a 2 x 4 stake. A small grassy knoll is located a short distance to the southwest of stone milepost marker 184 1/2. Instead of finding the state line at 43-00'00" North Latitude as expected, it was determined by the USGS surveyors to be about 4.5 seconds too far north. The tie in distance from the USGS point to the stone post was recorded to be 89.5 feet.

By using a handheld GPS receiver and a modern position that was converted to NAD83, the area was searched with a coin grade metal detector capable of locating the smallest pieces of iron. In the immediate area around the top of the knoll, small pieces of a rusted can were found as well as one larger 16d nail. This nail was lying flat and well away from where the GPS position placed the point. There were no signs of a rotted post where the nail was found. If this was the original nail, the top of the stake could have been broken off by cattle and displaced. There were also about six smaller nails found in the immediate area. A small depression on the knoll was found where water had been collecting and the soil was cracked from drying out. The distance from this depression to the stone milepost monument closely matched the recorded 89.5 feet distance of 1893. Two holes were dug in the depression, but nothing metal was found. It is likely this depression was made by later surveyors of the U. S. Coast & Geodetic Survey during the 1930's who were also looking for this point, but did not find it. It was hoped to find some evidence of the original point in order to set a permanent one in its place, but in the absence of having definite proof, nothing was placed. This point should be considered lost since a very thorough search was made and nothing conclusive was found to reestablish its original location with any certainty.

The original USGS description from 1893.

The prism pole placed next to the state line milepost marker to check the distance to the depression.

State Line Milepost 184 1/2 that was recorded to be 89.5 feet from the triangulation station.

Small pieces of metal, likely an old tin can, that were scattered around the area on the knoll.

A depression on the knoll where the monument might have once been located.

The total station set over the depression to measure the distance to the stone state line monument. Looking northeast.

A coin grade metal detector was used for an extended amount of time searching the area.

This nail was found lying flat near the surface, but was too far from where the GPS location placed the triangulation station.

Several small nails of this type were found in the area. No idea what they might have been used for at this location.

This brass 30-06 rifle casing was also found on the hill.

Looking north toward the Black Hills which are visible in the distance.

Back to USGS Black Hills Triangulation

© Jerry Penry 2019