hourglass valley

The adjective in the term hourglass valley draws on the outline of this ancient timepiece to suggest a geographic shape, as seen from above. The upstream part of such a valley narrows to the width of its watercourse before entering a pinched canyon, usually quite short. Where the watercourse emerges, the valley broadens again to form its lower reach. Mosaic Canyon in California’s Death Valley, with a floor composed of tessera-like, water-polished rocks of black, gray, and white, is one such valley. During a thunderstorm, water piling up at the head of the narrow canyon flushes through this midsection with a noticeable increase in velocity, then runs out freely over stones where the valley broadens out again. In a wineglass valley, an alluvial fan at the mouth of a steep, narrow canyon is seen to form the base or foot of the glass, the adjacent lower part of the canyon its stem, and where the canyon widens, higher up, one gets the impression of a final piece, the cup. Probably the full range of wineglass shapes, from champagne flute to red-wine goblet, is to be found in the western canyons. The Black Mountains on the east side of Death Valley, California, include a number of such valleys, among them Gower Gulch, Tank Canyon, and the canyons between Badwater and Mormon Point.

Terry Tempest Williams