Monument Rocks, the first National Natural Landmark in Kansas, was designated by the U.S. Department of Interior on October 31, 1968. These fifty-foot-high chalk spires are eroded remains of sedimentary deposits from the Western Interior Seaway, a late Cretaceous inland sea that stretched from the present-day Gulf of Mexico through Canada about 80 million years ago. The semitropical sea averaged 500 feet deep, had a silty bottom favorable for fossilization, and supported large swimming reptiles, huge carnivorous fish, sharks, turtles, many kinds of fish, and flying reptiles overhead. The Laramide Revolution that raised the Rocky Mountains also drained the inland sea, and during the Ice Age glacial melt and heavy rainfall flowing east carved softer sediments away, leaving chalk spires and badlands colored by mineral content; the sides of Monument Rocks reveal layers of iron, gypsum, bentonite, and giant clams. From 1858 to 1865, the Smoky Hill Trail, opened after gold was discovered at Cherry Creek near Denver in Kansas Territory, shortened travel to the gold fields by 116 miles compared with the Oregon Trail or Santa Fe Trail, and Monument Rocks became one of its most famous landmarks. The route had few markings and often lacked water, food, and firewood, and gold seekers crossed the plains on foot and with wagons, two-wheeled carts, and wheelbarrows; according to the Rocky Mountain News, many arrived half starved. Between 1860 and 1865 the trail lost favor because of frequent attacks in prime American Indian hunting grounds, while immense buffalo herds 20 to 30 miles wide roamed the prairie. In 1865, David A. Butterfield had the trail re-surveyed and sought troop protection for Butterfield’s Overland Despatch, whose first stagecoach left Atchison, Kansas, on September 11, 1865, and reached Denver twelve days later. The fare was $175.00, not including meals, which cost an additional dollar in the West. In June 1866, Bayard Taylor of the New York Tribune wrote that Monument Station, named for the chalk towers, looked at first like a deserted city with huge bastioned walls before separating into detached masses, some resembling colossal sitting statues. Its station house was built from large chalk blocks cut with a hatchet and cemented with raw clay. Though nicknamed Fort Monument, Monument Station was never officially a fort, but it served as a military post, home, and eating station for the Butterfield’s Overland Despatch.