Roche Percée Natural Arch

Roche Percée Natural Arch. . , Just above you in this section of the Big Manitou Bluffs is Roche Percée or Pierced Rock, a natural arch that once served as a landmark for historic Missouri River travelers. The name was given by unknown French voyageurs and engages, and eventually the nearby stream came to be known as Perche Creek, a corruption of Roche Percée. In the late 18th and early 19th centuries, Perche Creek emptied into the Missouri River right here. In the days before levees and wing dikes, the Big Muddy changed its course frequently. Today, the mouth of Perche Creek is three miles south, and this natural arch was, until recently, forgotten., On June 6, 1804, William Clark noted "Split Rock" in his journal. The name "Split Rock" first appeared on a map drawn in 1797 by James Mackay. In addition to Lewis and Clark, early travelers and fur traders who journeyed up the river before the age of steamboats observed the natural arch. In 1811, Henry Brackenridge went upriver with Manuel Lisa of the Missouri Fur Company to the Yellowstone River and back. Brackenridge noted "Roche percée" in his journal., In 1819, the Stephen Long expedition–famous for labeling the western Great Plains the "Great American Desert"–traveled past here on only the second steamboat to go up the Missouri. The expedition mentioned the "Roche a Piercè," and also a creek by the same name entering the Missouri near the natural arch. A few years later, in 1823, Duke Paul of Württemberg, a German naturalist, passed this way and described the natural arch, while referring to the nearby island as "Ill du rocher Percé" or Pierced Rock Island., Roche Percée and the Manitou Bluffs are composed of Burlington limestone, a sedimentary rock formed when shallow seas covered Missouri. Slightly acidic rainwater (resulting from its contact with decaying vegetation) seeped into the rock and dissolved the limestone. When the water found a way out along the face of the bluff, it created a hole. Over time, erosion widened the hole to give the appearance that it had been split or pierced. This process continues, and one day the arch will collapse., While Roche Percée Natural Arch can be seen from the Katy Trail State Park, it is actually located within Eagle Bluffs Conservation Area. That area also continues behind you to the west and includes wetland habitat for many thousands of migrating waterfowl and shorebirds. Eagle Bluffs is named for the bald eagles present during winter months.