Re: Another photo location - Arkansas Valley

In the photo, the geology appears to be the Cambrian Sawatch Quartzite resting on the Precambrian Basement complex rocks. The boulders in the foreground are certainly granite, or gneiss.
Referencing the Colorado Geologic map, the only place along the Arkansas River that you have this geology next to the tracks, with the beds dipping away from the track is about 4-5 miles east of Salida. On the attached map, the purple represents the sedimentary rocks (Sawatch) and the brown the basement. You can see that present highway 50 and the railroad are quite curvy there to follow the canyon. My guess is that it is in the approximate center of the attached Google Earth image