Aspen growth in Utah shows progressive creep downslope.
In geology, creep is the slow downward movement of materials. This slow movement of soil is not associated with erosion. It may occur on all sorts of slopes including those that are covered with vegetation. The steady downflow of soil and rock carries the vegetation with it. Creep may be caused by the growth of plant roots, the burrowing of small animals or trampling of larger creatures, frost movement, or successive drying and wetting that leads to shrinkage and swelling of the soil. See also drift.