Westward-bound emigrants entered Idaho after crossing Thomas Fork Valley and soon faced Big Hill, Soda Springs, and Fort Hall before continuing onto the harsh Snake River Plain. In 1843 wagons first passed Fort Hall, where travelers encountered dust, sagebrush, lava rock, mosquitoes, burning sun, cold nights, and concern from Native Americans, yet continued westward. Before the discovery of gold, California-bound emigrants followed the main Oregon Trail to Raft River before turning south on the California Trail, but gold seekers soon opened new routes including Hudspeth's Cutoff in 1849 and the Salt Lake Alternate, or Hensley's Cutoff, in 1848, which joined in the City of Rocks area and continued through Granite Pass. As emigrant traffic increased, grass and wood disappeared along the trail and water sources often became tainted, leading to use of alternate routes such as the South Alternate, Northside Alternate, Goodale's Cutoff, Lander Road, and Kelton Road. Letters and diary accounts from Jesse Looney, Peter Burnett, Osborne Cross, Elizabeth Dixon Smith Geer, Margaret Frink, Elizabeth Wood, Myra F. Eells, Henry Tappan, James F. Wilkins, Vincent Geiger, and Wakeman Bryarly recorded the rocky roads, dense sage, alkali dust, swarming mosquitoes, the division of the Oregon and California roads at Raft River, and the striking granite formations of City of Rocks, through which most travelers headed for California and some for Oregon.