Westward-bound emigrants entered Idaho after crossing Thomas Fork Valley, then faced Big Hill, Soda Springs, Fort Hall, and the harsh Snake River Plain, where dust, sagebrush, lava rock, mosquitoes, burning sun, cold nights, and a concerned Native American population made travel arduous. Before gold was discovered, 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 Alternative in 1848, which joined near the City of Rocks and continued through Granite Pass. As traffic increased and grass, wood, and water sources along the main routes were depleted, emigrants and early Idaho settlers heavily used alternatives including the South Alternative, Northside Alternative, Goodale's Cutoff, Landers Road, and Kelton Road. The route later known as Goodale's Cutoff had earlier served as a Hudson's Bay Company supply route between Fort Boise and Fort Hall because it offered a shorter path to important beaver streams and a major fur trade base, and British trappers using pack trains could cross rough lava stretches that discouraged wagons. Fort Hall employees therefore directed Oregon Trail wagon travelers along the Snake River to avoid lava flows between Lost River and Wood River, but after years of heavy use and overgrazing near the existing trail variants, new roads became necessary across southern Idaho's desert lands. In the area now known as Craters of the Moon, emigrants encountered an overwhelming panorama of buttes, sinks, and lava formations that showed why wagon traffic had been kept to the south bank of the Snake River, and this lava terrain was set aside as a national monument in 1924. Long before wagons used the route, Donald Mackenzie explored roads along the Snake River in 1811 and in 1820 found a more direct route across the Wood River Valley and Camas Prairie while leading Canadian fur hunters for the North West Company; searching for beaver, he found an old Indian trail that later became an Oregon Trail alternate known after 1862 as Goodale's Cutoff, and American fur brigades later used parts of it. In December 1832, Warren Ferris of the American Fur Company traveled the route from near Arco to a Snake River crossing. On July 20, 1852, John J. Jeffrey led an Oregon Trail wagon train over Mackenzie's route, successfully getting wagons past lava formations and other hazards, and in 1854 Jeffrey and his associates promoted the route and a ferry near the mouth of the Blackfoot River that charged five dollars per wagon and twenty-five cents per head of stock, though travelers complained that the rough, rocky road injured their cattle. Some early maps called it Jeffrey's Cutoff, but after 1862 it became known as Goodale's Cutoff when Timothy Goodale, a former fur trapper familiar with the country, guided a large wagon train along it to avoid Indian problems on the main trail and help travelers headed toward the newly discovered Salmon River gold mines. After leaving the main trail at Boise, the train made new wagon tracks as Goodale led it toward the vicinity of Cambridge; some tried to continue north with wagons toward the mines but abandoned them before reaching New Meadows, while the rest met John Brownlee, who was building a ferry across the Snake River and agreed to carry them for free if they built a wagon route to the ferry and out of the canyon, a route later much used by miners going to Boise Basin though wagon traffic took other routes.