'ShoreZone': Where art meets science on the Alaska coastline http://
About this NOAA Fisheries photo: Prince of Wales Passage, Prince William Sound July 1, 2004. Sea cliffs are a common feature of an eroding coastline. Igneous rocks, such as columnar basalts, are particularly strong and resistant to erosion. In the relatively wave protected environment of Prince William Sound, the cliffs erode primarily by thermal expansion of freezing groundwater seepage and rain water. The broken rock particles tumble into the sea and accumulate as talus at the base of the sea cliff. Ocean waves and currents act only to remove the finer particles from the debris pile. The vertical structure of the columnar basalt is emphasized in this image by intertidal plants. The upper extent of marine zonation on rocky shores in Prince William Sound is typically indicated by a horizontal band of black lichen Verrucaria maura occupying the portion of shore above the highest tide level and wetted only by sea spray. See more incredible photos here: http://1.usa.gov/138TjkA.
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