 Complete the following phrase:  In 1930 OBrien became a founding member of the Beach Erosion Board having been hired two years earlier by its predecessor organization. His interest in beach erosion led him to author a seven-volume study of the entire United States Pacific coastline, A Report on Sand Movement and Beach Erosion Along the Pacific Coast of the United States, in which he both addressed every American inlet and harbor on the Pacific and documented the phenomenon of littoral drift. OBrien continued to serve as a member of the Beach Erosion Board and beyond 1963, its successor organization, the Coastal Engineering Research Center until his retirement in 1978. In the late 1930s OBrien did consulting work for Weyerhaeuser Company to improve the flow in their log ponds. He also provided consultation on the placement of caissons during the construction of the ill-fated 