Миссуридегі Сен-Франсуа таулары

Mountain range in Missouri, United States

The St. Francois Mountains in southeast Missouri are a mountain range of Precambrian igneous mountains rising over the Ozark Plateau. This range is one of the oldest exposures of igneous rock in North America. The name of the range is spelled out as Saint Francois Mountains in official GNIS sources, but it is sometimes misspelled in use as St. Francis Mountains to match the anglicized pronunciation of both the range and St. Francois County.

The name of the range derives from the St. Francis River, which originates in the St. Francois Mountains. The origin of the river's name, which also was originally spelled "François" in the French manner, is unclear. The area, as part of the Louisiana district of New France, is near some of the earliest French settlements in Missouri, where many French place names survive. Some sources conjecture that the name honors St. Francis of Assisi (1181/1182–1226), the patron saint of the Franciscan order, but none of the region's early explorers were Franciscans. Others propose that Jacques Marquette, a French Jesuit, named the river when he explored its mouth in present day Arkansas in 1673. Before his voyage down the Mississippi River, Marquette had spent some time at the mission of St. François Xavier, named for the Jesuit missionary Francis Xavier (1506–1552). By comparison, the Appalachians started forming about 460 million years ago, and the Rockies a mere 140 million years ago. When the Appalachians started forming, the St. Francois range was already twice as old as the Appalachians are today. The intrusive rocks of the area are composed of three types: subvolcanic massifs, ring intrusions and central plutons. The subvolcanic intrusives are similar in geochemistry to the associated rhyolite volcanics, which they intrude into. They are granite with granophyric quartz, perthitic potassium feldspar, biotite and magnetite. They are intrusive into the rhyolites with development of fine grained granophyre at the contact. At depth they exhibit a coarse grained rapakivi texture. The subvolcanic granites are the most widespread igneous rocks and were thought to have been covered with extensive volcanics that have been removed by erosion. similar in scale to the Yellowstone Caldera complex. However, it is debated whether the igneous activity was related to a hotspot, like Yellowstone, or whether it was related to an ancient subduction zone.

The St. Francois Mountains are the center of the Lead Belt, a mining region yielding lead, iron, baryte, zinc, silver, manganese, cobalt, and nickel ores. Historic Mine La Motte near Fredericktown was the site of lead mining activity by the French as early as 1720. The area today accounts for over 90% of primary lead production in the United States. Granite has been commercially quarried since 1869 in the vicinity of Elephant Rocks State Park, a tor with huge weathered granite boulders. The red architectural granite quarried in the area has been used in buildings in St. Louis and other areas in the country. It is currently marketed as Missouri Red monument stone.

Hughes Mountain contains a good example of columnar jointing in igneous rhyolite, the same process that formed Devils Tower in Wyoming and the Giant's Causeway in Ireland. The columnar jointing in this area is called the
Devil's Honeycomb.

Mountains in this range include; Taum Sauk Mountain, Bell Mountain, Buford Mountain, Proffit Mountain, Pilot Knob, Hughes Mountain, Goggin Mountain and Lead Hill Mountain. The elevations range from Taum Sauk Mountain is the highest peak in the range, and the highest point in the state, with an elevation of 1772 feet (540 m). In the southernmost reaches of the range is Clark's Mountain, elevation 1450 feet (442 m), with the distinction of being the highest isolated point in the range and in the state; it reaches its top from surrounding terrain of about 900 feet (274 m) in less than 2 mile (3 km). Black Mountain, in Madison County, has the highest rise in elevation from its base, along the St. Francis River (540 feet above sea level) to its summit (1,502 feet above sea level), a rise of just under 1,000 feet in elevation.

Five Missouri state parks – Johnson's Shut Ins, Taum Sauk Mountain, St. Joe, Sam A. Baker and Elephant Rocks – are located in this region. Public lands held by the Missouri Department of Conservation provide access for hiking, backpacking, hunting, fishing, canoeing, and boating. The Mark Twain National Forest contains additional public lands, including the Bell Mountain Wilderness. A section of the Ozark Trail winds through parts of the St. Francois Mountains, including a popular segment that crosses Taum Sauk and Proffit mountains. The St. Francis River in this area is a whitewater stream in the spring when water levels are up, and it has hosted the Missouri Whitewater Championships annually since 1968.