EPOW - Ecology Picture of the Week

Glacier-Carved Valley of the Andes

Glacial Valley, Andes Mountains
Argentina

Explanation:  This week we present a beautiful example of a glacier-carved valley in the high Andes Mountains of southern South America, west of the town of San Carolos de Bariloche.  

The glacier obviously is gone, having melted after doing its engineering work.  Note the striking U-shape to the valley walls and floor which is typical of valleys carved by glacial ice.  

Also evident in this example are the high "cirque" headwalls of bare rock cliffs that once held the uppermost part of the glacier; and a typically oblong "tarn" lake that now holds the remnants of the glacial icemelt and now the rainwater and melted snowfall that still occurs in these elevations.  

And obvious is the verdant green carpet of shrubs and small trees that have spread across the valley flow and walls.  This is a classic example of "primary succession," when vegetation invades land laid bare and empty by such forces as glaciers, volcanoes, and other tectonic events.