Hampton, M.A., Griggs, G.B., Edil, T.B., Guy, D.E., Kelley, J.T., Komar, P.D., Mickelson, D.M., and Shipman, H.M., 2004, Introduction to cliff erosion in the US, in M.A. Hampton and G.B. Griggs, Coastal Cliff Erosion: Status and Trends. US Geological Survey Professional Paper 1693; p. 1-7; http://pubs.usgs.gov/pp/pp1693/.