West of longitude 110° it will be noted that two features stand out in bold relief, namely, a mitten-shaped mountain labeled FOSSIL (probably the Trident) and the crude outline of South Arm and Thumb of Yellowstone Lake. These two landmarks may be used as guide posts in following Colter’s reconstructed loop through Yellowstone. Colter’s authentic east loop journey, already described, brought him approximately to the 110° meridian. Colter’s mitten-shaped landmark lies about seventy-five miles due west of the border on his second map sheet, but Clark’s dotted line depicts Colter’s route fifty miles south of the mountain shaped like a mitten and marked FOSSIL. It is valid to inquire how Colter could discern its shape or know of its fossils from that distance. His Indian friends knew nothing about fossils. The dotted line does not cross or even skirt this mountain. To reach the “Fossil Mountain” from Salt Fork, Colter could ascend by Elk-Wapiti or Fishhawk creeks. Each meets the requirements of direction and distance, and there is a good chance that somewhere along one of these routes a large petrified fish, or something like a fish, was seen then and may be eventually found. Such a discovery would remove all doubt about the direction in which he traveled.[364] [Illustration: Western section of Coulter’s route. Logic and a reasonable sense of procedure would support this route as the trail of Coulter’s Yellowstone discovery. Conclusive proof is lacking.] From the “Fossil Mountain” Colter probably descended Pass Creek to Thorofare Creek, which he followed to the Upper Yellowstone River. Then he might have ascended either Falcon, Lynx, or Atlantic creeks, preferably the latter, to Two Ocean Pass. Crossing the Continental Divide, he would then descend Pacific Creek, skirting Big Game Ridge, and cross the South Fork of Snake River, within the present confines of the Park. Thence he could go along Chicken Ridge, from where he would frequently view South Arm, headed toward Flat Mountain Arm. After crossing Solution Creek he would strike West Thumb.[365] The validity of this itinerary is wholly sustained by the genuine features of this area as they appear upon the Map of 1814. Indeed, the route seems obvious and indisputable in view of the actual conditions existing. On a crude map, where there are numerous, similar streams, various combinations are, of course, possible. Leaving West Thumb, Colter would have circled the lake to its outlet and followed it to the Hayden Valley thermal area. Dragons Mouth and Mud Volcano were undoubtedly features that contributed to the vivid impression he carried away and transmitted to others. Even the “Hot Spring Brimstone” characterization on the Map of 1814 mildly suggests explosive thermal activity. The phrase also suggests that Colter mapped a geyser basin.[366]