It was a valid reaction for Clark to have become suspicious of Colter's reliability, and the substitution of his own geographical speculation for Colter's Yellowstone sketch was probably sincere. Clark was too honest to depict the delusions of an "insane" man. Also he was very anxious to have a reasonably complete and integrated map. The only alternatives were to allow the Colter marvel sheet to appear or else to mark a considerable area "unexplored." He was caught in the bonds of uncertainty and made a compromise. The result was a sheet of bogus geography which is entirely incongruous, not only with the facts, but with Clark's uniformly excellent map work.[361]
Clark's choice of alternatives only complicated the problem of his cartographer. Lewis no doubt recognized the vast discrepancies between Colter's genuine depiction and Clark's counterfeit so he evidently decided upon a compromise of his own. How this expert reconciled the conflicting data of the two map sheets into one pattern is at once a masterpiece in cartography and psychology. The technique he adopted might be called "double entry map making." He used the Yellowstone Lake part of Colter's sketch as an element for a concealed map; it appears as a mountain range. Such a grotesque range cannot be found in any of the surrounding territory, but when visualized as a lake it is amazing how it conforms to what a trapper traveling a logical route would have seen of Yellowstone Lake, namely, the South Arm and Thumb. Lewis shied away from any clear-cut representation of the geyser region. However, besides including the disguised lake portion of Colter's map, he did other things to "poke fun" at Clark's speculations. He drew Lake Eustis in the manner of a gargoyle. It must have been deliberately "satanized." Nothing with such a preposterous shape was ever known among men. Why didn't Clark revolt at this representation? Surely he never drew anything like that himself. That is not all of Lewis' "fun making." He drew still another lake and gave it the shape of a deformed piece of liver. Its appearance is ridiculous in the other extreme,[362] but, as if to add insult to injury, Mr. Lewis raised a question as to this lake's legitimacy. Clark named it Biddle in honor of his patron, Nicholas Biddle, whereas, upon the English version, the name appearing is Riddle! Lewis was able to "get away" with this performance because Clark did not see any proofs, only the published work.