April 17, 2003
Most geological changes occur so slowly that we need to look for subtle signs, which give an indication that conditions are changing. The aspen trees in the above photo show that the soil in which they are growing has been moving downslope in a mass wasting process known as creep. The top of the soil layer moves faster than the soil beneath, causing the young trees to bend downslope. As the roots stabilize the soil, creep is greatly diminished and the trees can then grow straight. The photograph was taken on the Wasatch Plateau south of Salt Lake City, Utah.
When this EPOD was posted, a reader suggested that the bent trees in this image were caused by the downslope movement of a thick snow cover. Although similar growth is seen due to the downslope motion of the soil, the author concurs that this bending of tree trunks is more likely to be caused by snow movement, especially when the trees were young.