Mormon emigrants traveling west along the north side of the North Platte River saw topographical features not visible from the south side, and these landmarks helped guide the Latter-day Saints toward Utah Territory. Thirty-one miles west of Ash Hollow, a line of bluffs called Cobble Hills marked a change in the landscape from sand to gravelly limestone. At these bluffs on May 22, 1847, Orrin Porter Rockwell, a guide with the vanguard Mormon Pioneer Company, returned to camp after going to a high bluff about a mile northwest and reported seeing Chimney Rock. William Clayton, concerned about the distance given on the Fremont-Pruess map, climbed the highest bluff with his telescope despite being footsore and weary and confirmed that Chimney Rock could be seen very plainly with the naked eye from twenty miles away. While observing the scenery, which he called romantic, he was struck by a large rock projecting from one corner that resembled an immense frog’s head with its mouth parts open, and he thought the bluffs should be named Frog’s Head Bluff. Accounts from Thomas Bullock, Howard Eagan, and Catharine Wooley also recorded Crab Creek, the bold bluff, and the sight of Chimney Rock from this area in 1847 and 1848.