By wagon, the encampments in the Guernsey area were a day's trek from Fort Laramie, and emigrants had three choices of camp sites there: Register Cliff, Warm Springs, or Cold Springs, the farthest encampment. In 1842, Lieutenant John C. Fremont led a mapping expedition of the Oregon Trail, and according to his map maker, Charles Preuss, the flat area just below this site is the most likely place where the expedition camped on 21-22 July 1842. While camped there, Fremont noted in his report to Congress that Fort Larami would be a suitable place for a military post. Many period documents described Warm Springs as the Emigrant's Wash or Laundry Tub because of its natural warm water temperature. In 1842, Fremont wrote that ten miles from the fort, his party entered the sandy bed of a creek where on the left bank a very large spring gushed with considerable noise and force out of the limestone, and on the opposite side, a little below the spring, stood a lofty limestone escarpment partially shaded by a grove of large trees. Cold Springs Pass was used to reach Cold Spring Camp Site. Register Cliff stood near a mile-long cliff of soft sandstone used as a name register by thousands of emigrants from 1847 on, although no emigrant diary mentions inscribing names or initials on the cliff. Near Register Cliff were also the War and Guerrier Trading Post from 1852-1855, the Mills and Janis Trading Post from 1858-1860, and the Sandy Point Pony Express Station from 1860-1861.