The formation of rhythmic patterns at the Field Research Facility (U.S. Army Corps of Engineers, Duck, North Carolina) under extreme wave climatic conditions is analyzed in terms of the partial standing oscillations formed by the superposition of the incident edge wave and the wave reflected by the structure. The reflection coefficient at the pier is evaluated with an existing model used for the propagation of an edge wave through a permeable structure perpendicular to the coastline, modified here to deal with an arbitrary beach profile. The mass transport patterns under the partial standing edge waves are found to resemble the beach cusps and the crescentic bars observed on the shore, north of the pier, after a series of storm events.