Such a platform is presently being formed offshore from Natural Bridges State Park by the scouring action of thousands and thousands of waves. In sum, it is the combination of the rise and fall of sea level and of the constant uplift of the land which has created the flight of marine terraces we see today. The ancient seafloor which comprises the lowest Santa Cruz terrace and upon which the visitor s center is built is approximately 100,000 years old. Coastal Dunes Coastal dunes are similar in many respects to the sand dunes one finds in the desert but with some significant differences. The main difference is the presence of water in the environment.
Coastal dunes have a tendency to become vegetated.
As a result of this stability, people have a tendency to build things on the dunes or besides the dunes. A serious problem in many coastal dune areas is the destabilization of the dunes by dune buggies, people walking on the vegetation, or other anthropogenic impacts on the vegetation. When the dunes become destabilized the begin to move. In areas such as the Oregon coast where the dune fields are 50 miles long and the dunes as much as 200 feet high, this can cause some obvious problems. A close examination of the dune sand reveals that it is typically finer than the sand found on the adjacent beach.