A number of good guesses.
The location is at MP 282.61, the Resurrection No. 1 spur on the D&RGW's Ibex branch out of Leadville. Branch was orginally narrow gauge, parts were dual gauged, and the entire thing standard gauged by 1917. But this short siding to one of the mine tipple apparently was never standard gauged as the ties and spike holes are narrow gauge. This location is over 11,000 feet, highest line on the D&RGW. When it was abandoned in 1944, Marshall Pass became the highest point on the D&RGW.
Jerry Day