The debris and deposits usually consist of a jumbled mixture of all the geologic soil layers that make up the slope as well as vegetation that moved down the slope. This atlas can often be found in the public library reference or atlas section or at local county planning and engineering departments. Return to top Natural Slope Processes Under natural forces of gravity, wind, and water, coastal slopes continue to change. The majority of erosion in the Puget Sound area is due to the wearing away of soil or rock by the movement or flow of water. Erosion can also include wearing away of soil by wind and ice.
Landslides occur when a mass of soil moves down the slope under the force of gravity.
Puget Sound Coastal Slope Processes Figure 4. As erosion and landsliding occur, they change the shape of slopes. In general the overall shape of the slope will become flatter and less steep. This tends to increase the overall stability of a slope. However, erosion and landsliding can leave localized areas of a slope steep and unstable.