The inlet known as Devil's Churn developed over many thousands of years as wave action carved into the basalt shoreline, forming a deep sea cave whose roof eventually collapsed. As the tide comes in it can throw spray several hundred feet into the air when the waves reach the end of the churn.
A sea cave, also known as a littoral cave, is a type of cave formed primarily by the wave action of the sea. The primary process involved is erosion. Sea caves are found throughout the world, actively forming along present coastlines and as relict sea caves on former coastlines.
Littoral caves may be found in a wide variety of host rocks, ranging from sedimentary to metamorphic to igneous, but caves in the latter tend to be larger due to the greater strength of the host rock.
In order to form a sea cave, the host rock must first contain a weak zone. In metamorphic or igneous rock.
The driving force in littoral cave development is wave action. Erosion is ongoing anywhere that waves batter rocky coasts, but where sea cliffs contain zones of weakness, rock is removed at a greater rate along these zones. As the sea reaches into the fissures thus formed, they begin to widen and deepen due to the tremendous force exerted within a confined space, not only by direct action of the surf and any rock particles that it bears, but also by compression of air within. Adding to the hydraulic power of the waves is the abrasive force of suspended sand and rock. Most sea-cave walls are irregular and chunky, reflecting an erosional process where the rock is fractured piece by piece. However, some caves have portions where the walls are rounded and smoothed, typically floored with cobbles, and result from the swirling motion of these cobbles in the surf zone.
The pounding, exploding waters of Devils Churn are at their best during high tide and winter storms. At the Devils Churn you’ll find restrooms, an information station (summer only), coffee shop and wheelchair accessible viewpoint. See the Churn from the viewing platform located alongside Highway 101, or on foot along the Restless Waters Trail. A recreation pass is required to hike the trail. Visitors are urged to be cautious when visiting the churn as it can be dangerous.
In order to log this cache please email me the elevation at the listed coordinates, estimate the drop to the churn area and the maximum height height of the spray over the rocks. Also please state how the informational sign says you will feel the ocean movements.