However, in association with, and following episodes of erosion, there are segments of the Oregon coast where the problem is too much sand. These areas tend to be located at the north ends of headland-bounded segments of shoreline consistent with littoral cell circulation and sedimentation. Mass wasting refers generally to a broad range of gravity-driven rock, soil, or sediment mass movements. This includes weathering processes that result in gradual bluff recession, such as direct wind and rain impact. Here, the term mass wasting refers to episodic slope movements also known as landslides.
Material composition is a primary control on slope stability.
Headlands, for example, while not immune to mass wasting, do not readily give way. In contrast, soft bluff-forming sandstones and mudstone are highly susceptible to slope movement. Prolonged winter rains saturate these porous bluff materials, both loading the slope and lowering cohesive strength, to further decrease slope stability. The geometry and structure of bluff materials also affects slope stability. They define lines of weakness and control surface as well as subsurface drainage.