Deep Sea Sea Stacks
The irregular coastline of the Olympic peninsula in northwestern America is the result of differential erosion rates working on the accreted tectonic melange that was scraped of the deep sea trench during the ocean plate subduction process. Harder rocks form headlands while the softer rocks erode into bays. Wave breaking action is more concentrated in the shallow waters towards the headlands and dissipated towards bays. Faults, joints or bedding planes in the 20 million years old Hoh formation sediments resemble lines of weakness and are hence especially exposed to erosion. This forms so called back-to-back caves at headlands. Progressing erosion forms these into arches that connect the headland with the mainland. After the arch collapsed the headland becomes isolated and further wave action forms sea stacks.
August 2008
Canon 20D, Canon EF-S 10-22mm, f/16, 8 sec, ISO 100, tripod