USGS
Triangulation Station
"CROW PEAK"

1897

Jerry Penry
September 25, 2015

Crow Peak is a prominent hill located 5 miles southwest of Spearfish, South Dakota. The triangulation station for "Crow Peak" was established during November-December 1897 by Frank Tweedy of the U. S. Geological Survey. The usual mark placed at other locations during the 1897 triangulation network in the Black Hills was a 1" diameter copper bolt, however, at Crow Peak the monument was described as being a brass wedge. The copper bolts were slotted on the bottom end. Before inserting the bolt into a drill hole in rock, a brass wedge was placed in the hole and then the bolt was driven down onto the wedge which expanded the bolt and secured it in place. One theory as to why a bolt was not placed on Crow Peak was that it might have been lost when the surveyors climbed to the summit. Another explanation could be that the rock at the summit was too brittle and a brass wedge was cemented into an existing crack in a rock.

With a modified GPS position to define the location, surveyors Kurt Luebke, Dave Ingram and Jerry Penry hiked to the summit. A metal detector was used at various places on the summit, but other than some nails, wire, and brass ammunition casings, the wedge was not found. The rocks on the summit have been broken apart many times with some thrown over the edge. A very thorough search was made while on the summit and if the brass wedge still exists, it cannot be easily found.

Description for "Crow Peak" in the USGS 19th Annual Report for 1897-98.

Drawing of a brass wedge (left) normally used with a copper bolt.

Crow Peak as viewed from the west. The summit is on the southern end of the peak.

Sign located on the summit of Crow Peak.

Kurt, Jerry and Dave on the summit.

Rocks scattered around on the summit.

Broken rocks in dirt that were checked with the metal detector.

The general location where the modified GPS position placed the marker.

The hiking trail leading to the summit.

Spearfish, South Dakota in the distance as viewed from the summit of Crow Peak.

The route used to reach the summit from the trailhead parking lot.

Back to USGS Black Hills Triangulation

© Jerry Penry 2015