The American west is always good for dramatic scenery, and human intervention has often made it even more striking. The 1905 picture above is titled “Canyon of the Rio las Animas, Colorado” and it shows a narrow-gauge train on the Denver & Rio Grande Railroad in the valley. The railroad line I’ve ridden most often over the last 40 years is the New York Central main line from New York to Albany, which is also in a river valley, but the Hudson line runs mostly right at the edge of the river, which is at sea level for the entire 150 miles. The D&RG is a whole different idea of running a railroad in a valley: you can see where parts of the cliff have been removed to create a ledge for the tracks. The fact that a seven-car passenger train needs two engines also gives a sense of how mountainous the terrain is.
The use of narrow-gauge track – in this case, 3 feet instead of the standard 4 feet, 8-1/2 inches, was a cost savings measure. The amount of steel rail was the same, but the amount of track bed that had to be built was reduced (for example, the amount of cliff that had to be blasted out in this valley), the rolling stock was smaller and cheaper, and smaller engines made it easier to make sharp turns. The big railroads were competing on speed and capacity; smaller ones were counting on being the only service in less-populated and hard-to-reach areas, and could sacrifice speed and capacity. The D&RG had both narrow and standard gauge for quite some time, using the common trick of having three rails to allow trains of both sizes to run on the same track in areas where the gauges met. Here’s a 1914 map of the railroad, with standard gauge in red and narrow gauge in black:
The valley of the Animas River is where the short branch line from Durango to Silverton runs, near the southwest corner of Colorado. This branch has survived the general disappearance of local train traffic in the west and the loss of all passenger rail in Colorado other than the old Union Pacific main line (through Denver and Grand Junction) as a heritage railroad. You can ride an old steam-hauled narrow-gauge train through the terrain in that picture above.