This is Steamboat Rock (and Tug Rock), aptly named landmarks northwest of Fort Collins, Colorado.
"...Camped half a mile to the right of the road...crossed Evans old [1849] Trace...[camped] on a hill by the side of a large, steep Red Mt..." June 29, 1850, Cherokee Diary.
"...the red bluffs [sketched]..." June 22, 1850, Diary.
