Regional Guide: Rocky Mountain Valleys

The Rockies are less a single range than a stack of parallel ridges separated by long, high valleys. Knowing the four big categories makes any Rocky Mountain road trip make more sense.

The Parks (Colorado)

Colorado has four grassy basins — North Park, Middle Park, South Park, and the San Luis Valley — ringed by peaks and floored by sagebrush or wet meadow. They're structural basins, not river-cut, which is why the floors are so flat.

Jackson Hole (Wyoming)

A textbook fault-block valley. The Tetons rise abruptly on the west because the valley floor dropped down along the Teton Fault. Drive US-26/89/191 the length of the park to see it — see the Jackson road guide for the highway stops.

Glacial troughs (Montana & northern Wyoming)

Glacier National Park is the clearest place in the lower 48 to see U-shaped valleys, hanging valleys, and cirque headwalls in one drive. Going-to-the-Sun Road is the tour — see the West Glacier road guide.

San Juan canyons (Colorado)

Steep V-shaped river canyons cut by the Uncompahgre, San Miguel, and Animas rivers through volcanic rock. Telluride sits at the head of one — the Telluride road guide covers the San Juan Skyway approach.