Sioux Falls took its name from the falls in the Big Sioux River, which stood out in a sea of grass and drew both explorers and land speculators to the area. Joseph Nicollet, Lewis & Clark, James Allen, and Philander Prescott sent first- or second-hand accounts of the falls back East, and in 1856 two groups of speculators rushed in to claim nearby land, believing the river could power factories and attract businesses and settlers who would then buy their property. Their early optimism was undercut by the Civil War, fear of confrontations with native tribes, and a depression that discouraged settlement and slowed railroad construction, and the townsite was abandoned in 1862 after violent conflicts between settlers and native tribes nearby in southwest Minnesota. About 15 years after the first speculators arrived, a new wave of businesses and settlers began building Sioux Falls, with mills, quarries, and other industries developing around the falls to use the river and rock, and the city flourished after railroad service arrived in 1878. Captain James Allen, writing on September 13, 1844, portrayed the falls as a remarkable feature of the river and country, with massive quartz rock, a drop of 100 feet in 400 yards made up of several perpendicular falls, split and broken rock in irregular and fantastic shapes, deep chasms extending from the stream, and little timber on the borders or bluffs.