Contributed by Richard Estelle, Palmer Museum of History & Art
Most everyone living in the Matanuska Valley has experienced the local wind. What many may not realize is the considerable effect the wind has had, and continues to have, on the physical environment of the Valley and, particularly, the farmers who settled here.
A major attraction of the Valley for farmers was the deep, fine-textured, workable soil they found here. However, thousands of years ago, there was no soil in this Valley because the glaciers flowing out of the Matanuska and Knik Valleys ground down and carried away everything above bedrock.
But over those thousands of years, as the front of the glaciers melted away faster than the ice mass flowed down the mountains, land that had been covered with the ice became exposed. Left behind were vast quantities of rock fragments the ice had broken from the surrounding mountains. This “gravel” ranges in size from house-sized boulders down to the tiniest fragments.
As meltwater from the glaciers flowed downstream, it picked up these tiniest particles (producing the grey-colored water we associate with glacial streams) and deposited tons of the fine “mud” on stream banks along the way. When the mud banks dried out, the tiny particles became easily disturbed by the wind.
Cold, heavy air above the mountain glaciers flows downhill to replace the warmer, rising air above the ocean, creating strong winds which pick up the tiny particles and carry them along as “dust”. As the strong winds slow down over the valley floor, they drop their loads of dust, or “silt”, to accumulate as soil. Over the thousands of years, forest vegetation developed on this new, wind-blown soil (called “Loess”) to further slow the winds and cause more silt to fall. By the time homesteaders and farmers settled here, they found some lands on the eastern portion of the valley had accumulated over six feet of this topsoil.
The Knik and Matanuska winds continue to transport their silt into the valley today, to be deposited as the trees and other obstructions interrupt the air flow and cause the fine “glacier flour” to fall. However, it may not stay where it has fallen. If this wind-blown soil is left exposed to the winter winds on one farm, it’s likely that some will be picked up and deposited in the woods or covered field of the next farm downwind.
Our photo this month illustrates just how much soil may be lost from a field left through a single winter without a cover crop for protection. We see that the handful of carrots left unharvested the previous fall have had a couple of inches of soil blown away from around them. And winter, with its robust Matanuska winds, appears to not be over yet!