Readers may be intrigued by a fascinating footnote to the article on the Semi-Arid Land Surface Atmosphere Program (SALSA) study of the Upper San Pedro River Basin (USPB) in Arizona (Eos, November 14, 1995, p. 465). Along the banks of the San Pedro River within the first congressionally designated Riparian National Conservation Area, the “narrow riparian corridor (50–300 m wide)” that has been declared one of the “12 Great Places of the Western Hemisphere” by the Nature Conservancy, has existed for no more than half a century! [See Richard Hereford, 1993 Geological Society of America Special Paper 282, 46 pp.]