IV PREFACE. 



It may be well to indicate here the general routes of travel by which 

 the country has been explored. In the fall of 1868 with a small party of 

 men I crossed from the White River to the Yampa, and camped at the foot 

 of Junction Mountain; thence I passed northward across the Snake River 

 to the Pine Bluffs, and thence westward across Aspen Mountain to the 

 Green River, and up the bank of that stream to Green River Station; 

 thence I crossed to Bryan, on Black's Fork, and down that stream to 

 its mouth, then went south to the. Cameo Mountains; thence eastward 

 to Quien Hornet Mountain; thence to Flaming Gorge, and from this 

 latter point to Ashley Park, and from Ashley Park to Brown's Park. From 

 Brown's Park I went through the Escalante Peaks, near the junction of the 

 Yampa with the Green ; thence eastward past Junction Mountain to the 

 White River. 



The course thus laid down is the general one of the pack train, but I 

 myself branched from it in many ways. 



On this journey I first discovered the succession of Cenozoic and Meso- 

 zoic groups, but did not divide the Upper from the Lower Green River, nor 

 did I draw the plane of separation between the Upper Green River and 

 Bridger Groups where I do now. 



Early in the spring of 18G9 I again crossed from the White River to 

 the Yampa, camped at the foot of Junction Mountain, and spent a few 

 days in the study of the adjacent region. I proceeded thence to Brown's 

 Park, in which I camped for a few days, reviewing the geological studies of 

 the previous fall. I then passed out of the park through Red Creek Canon, 

 from its head, crossed the divide, and proceeded westward to the Green River, 

 and camped again at Flaming Gorge for a few days. Thence I went up 

 Henry's Fork, studying the region on my way, and crossed the divide to 

 Fort Bridger. 



A few weeks Subsequent 1 started on. a boat trip to explore the lower 

 Green and the Colorado River of the West, On my way I passed through 

 the Uinta Mountains, stopping from time to time to make sections and to 

 make geological studies of the country along the walls of the canons. 



Again, in 1871, I had a boat ride down the river. On this trip Mr. 

 .John F. Steward, of Piano, Illinois, was my assistant. We extended our 

 studies on either side of 1 lie river for a distance of from ten to twentv miles. 



