We have recognized the Ferris map of 1836 and the De Smet map of 1851, based on the undated “Bridger Map,” as the earliest authentic maps of the Yellowstone Park area, but these remained unpublished and unheralded. The Raynolds and DeLacy maps, though purporting to reveal the scenic wonders, were scanned mainly by single-minded gold seekers before they became obsolete. As to other contemporary published maps, the persistence of this geographical blind spot in the face of testimony offered by such prime witnesses as Potts, Ferris, and Bridger is demonstrated by the fact that for over half a century of map making by such respected cartographers as John Arrowsmith, Albert Gallatin, Bonneville, Fremont, and Gouverneur K. Warren there was no improvement in the “Yellowstone Park” section of the Clark map of 1810, with its “Lake Eustis” and “Hot Spring Brimstone.” There were only occasional meaningless variations of nomenclature. For instance, on the Robert Greenhow map of 1840 and on E. F. Beade’s “New Map of the Great West,” published in 1856, “Hot Sulphur Springs” is substituted. On Charles Wilkes’ “Map of Oregon Territory” which appeared in 1845 and on the J. H. Colton map which accompanied Horn’s Overland Guide, published in 1856, this phenomenon becomes “Steamboat Sp.” and Eustis is transformed into “Sublette’s L.” However, on the famed Colton map of 1867, just five years before the first boat was launched from its shores, the phantom lake—Eustis, Sublette, or Yellowstone—has disappeared entirely! Contemporary newspaper accounts and later published reminiscences reveal several prospecting expeditions which traversed the Park area during the period 1864-1869, but the partial and foggy reports of “a lost world” given out by these treasure hunters did little to dispel the curtain of mystery stubbornly surrounding the area. The cumulative effect of such reports and rumors, however, was destined soon to convince intelligent listeners that no wild tale could be so persistent, and that there must be something at the headwaters of the Yellowstone worth looking into. In September 1869, David E. Folsom, Charles W. Cook, and William Peterson packed south out of Diamond City, Montana, without distracting thoughts of beaver hides or gold, but with the express purpose of exploring that neighborhood and reporting their findings without adornment. General Henry D. Washburn, Hon. Cornelius Hedges, Hon. Nathaniel Langford, Dr. Ferdinand V. Hayden, and Photographer William H. Jackson were standing in the wings. The brief era of definitive discovery was dawning. [Illustration: First picture ever made of Yellowstone Lake from watercolor by Henry W. Elliott, 1871. Picture courtesy of Haynes Studios, Inc.] Selected Bibliography for COLTER’S HELL AND JACKSON’S HOLE