Scotts Bluff, a dramatic series of clay and sandstone highlands, became a major landmark on the Oregon Trail after emigrants heading west crossed six to eight weeks of flat grasslands. In the 1840s, deep ravines near the bluffs forced early wagon trains to bypass the area, but in 1851 a wagon route opened through Mitchell Pass, and for more than a decade Oregon Trail pioneers drove their teams and wagons through it. The route also carried pioneers, gold seekers, freighters, cavalry troops, soldiers, and Pony Express riders. Scotts Bluff left a strong impression on thousands of overland travelers in the 1840s and 1850s. Emigrants on the Oregon Trail approached on this side of the North Platte River, while those on the Moron Trail saw the bluffs from the opposite bank. Forty-niners bound for the California Gold Rush also passed this way before turning west of the Rockies onto the California Trail. Emigrants bound for Oregon or California loaded their possessions and provisions into small canvas-covered wagons pulled by two to four yoke of oxen, while families walked alongside. In the 1850s and 1860s, large Conestoga wagons drawn by six to ten yoke of oxen hauled freight to military posts over this route.