Scotts Bluff was a thrilling sight for emigrants journeying west on the Oregon Trail after weeks of crossing the wild, expansive plains, as this massive clay and sandstone promontory rose some 800 feet above the valley floor and looked like a dazzling fortress or high-walled city. It was also a barrier, because badlands on the north side were impassable for wagons and deep ravines ahead blocked the way to Mitchell Pass, forcing wagon trains in the 1840s to bypass the area. With engineering assistance from the U.S. Army, the Oregon Trail opened through Mitchell Pass in 1851. On Wednesday, June 13, 1849, emigrant Lucy Foster Sexton wrote that after making about 10 miles and halting about noon opposite Scotts Bluff, she saw a splendid pile of bluffs, probably nearly 400 feet in height, standing in an isolated position, whose changing views resembled large castles with attendant offices and chapels, magnificently grand beyond any of the puny works of mortal man.