A long time ago glaciers covered what is now the Matanuska Valley in Alaska. For many thousands of years meltwaters from the Matanuska Glacier fed the Matanuska River, which has carved a winding channel through the Talkeetna and Chugach Mountains. The foot of the Matanuska Glacier is a great pile of silt and during the summers the river is a gray color, like city sidewalks. The gray is silt from the glacier. The river flows through a wide channel which is a thick bed of very fine, glacial silt. In the winter the glacier doesn't melt very much, so the river flows a clear green or deep blue color.The winter wind called the Matanuska flows along the river channel and when it reaches a sufficient speed, it picks up silt from the dry parts of the river bed. This silt becomes suspended, flowing many miles on air currents until some resistance to air flow is reached. On the leeward side of trees you can often see drifts of silt A benefit is renewal of top soil. Click on "Zoom In" to view the silt shadow beneath the willow.  The Matanuska Wind can also be detrimental to the land, stripping top soil from unprotected fields once any snow cover has blown away. Return to Winter Winds.