Tuesday, February 23, 2010
Freezing and Thawing in the Blue Ridge Mountains
We are finally seeing some thawing and melting of snows in the Blue Ridge Region. Storms and low temperatures have kept much of the Southern Appalachians locked in snow and ice since before Christmas. Brief respites of sunshine and temperatures above freezing are now producing running waters generated by melting snow.
This brings to mind the geologic processes that have produced the Blue Ridge Mountains as we know them. The freezing and thawing cycles through the millennia have served to create the many rock formations, rounded mountain tops, and rock strewn streams that provide the environment of some of the oldest mountains in the world.
During the winter water fills cracks and crevasses in large rocks and is often held in place by snow or ice. The water then freezes and expands producing pressure within the rock. This process occurs over and over again through the years eventually breaking the rock into pieces. These reduced rocks then fall down slope and the freezing and thawing process continues breaking the rocks down to sizes that can eventually be carried by rushing waters during floods further down the slope. These rocks sit in stream beds and drainages smoothed and polished to form the sparkling pebbled habitat for trout, macro invertebrates, and other aquatic life.
There is very little soil held on the steep mountain slopes of the Blue Ridge. This perpetual freezing and thawing is one of the contributors to the eroding of the mountains in the Southern Appalachians.
With the absence of vegetation and the surface covered with ice and snow many people think of winter as being a time of idleness in the mountain environment. In every season there are continuous natural processes occurring that produce or influence the habitats of the wild and their partners, the human race.