St. Francois Mountains
From Wikipedia, the free encyclopedia
| Saint Francois Mountains | |
| Mountain Range | |
 A view towards the St. Francois range from Knob Lick Mountain, a granite and rhyolite knob on the edge of the range
|
|
| Country | United States |
|---|---|
| State | Missouri |
| Highest point | Taum Sauk Mountain |
| - elevation | 1,772 ft (540 m) |
| - coordinates | 37°34′13″N 90°43′40″W / 37.57028°N 90.72778°W |
| Geology | igneous |
| Period | Precambrian |
 A relief map of Missouri showing the St. Francois Mountain region (red).
|
|
The St. Francois Mountains in southeast Missouri are a 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.[1]), but it is sometimes misspelled in use as St. Francis Mountains to match the anglicized pronunciation of both the range and St. Francois County.[1][2][3][4]
Contents |
[edit] Name
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 "Francois" 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 source conjecture that the name honors St. Francis of Assisi, the patron saint of the Franciscan order, but none of the region's early explorers were Franciscans.[2] 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 Mississppi Marquette had spent some time at the mission of St. Francois Xavier, named for the Jesuit missionary Francis Xavier.[2] The spelling of the river's name shifted from "Francois" to "Francis" in the early 20th century.[2]
[edit] Geology
Formed through volcanic and intrusive activity 1.485 billion (1.485 x 109) years ago.[3] By comparison, the Appalachians started forming about 460 million years ago, and the Rockies a mere 70 million years ago. When the Appalachians started forming, the St. Francois range was already twice as old as the Appalachians are today.
The Saint Francois Mountains were formed by volcanic activity, whereas most of the Ozarks are a dissected plateau where localized vertical relief was caused by erosion following uplift during the Pennsylvanian and Permian periods produced by the Ouachita orogeny to the south. Elevations and strata dips in the Ozark structural dome generally radiate downward and outward away from the Saint Francois mountains.
These ancient mountains may be the only area in the American Midwest never to have been submerged, existing as an island archipelago in the Paleozoic seas. Fossilized coral, the remains of ancient reefs, can be found among the rocks around the flanks of the mountains. These ancient reef complexes formed the localizing structures for the mineralizing fluids that resulted in the rich ore deposits of the area.
[edit] Mineral resources
The St. Francois Mountains are the center of the Lead Belt, a mining region yielding lead, iron, barite, 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 bolders. 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 as Missouri Red monument stone.
[edit] Structural features
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.
[edit] Peaks
Mountains in this range include; Taum Sauk Mountain, Bell Mountain, Proffit Mountain, Pilot Knob Mountain, Hughes Mountain, Russell Mountain, Goggin Mountain, and Buford Mountain. The elevations range from 500 feet to 1,772 feet (167 to 540 meters). Taum Sauk Mountain is the highest peak in the range, and the highest point in the state, with an elevation of 1772 ft. (540 m).
[edit] Recreation
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 annualy since 1967.
[edit] See also
[edit] References
- ^ USGS GNIS: Saint Francois Mountains
- ^ a b c St. Francois County, Missouri Place Names, Western Historical Manuscript Collection
- ^ Denison, Rodger E., et al., Geology and Geochemistry of the Precambrian Rocks in the Central Interior Region of the United States, Geological Survey Professional Paper 1241-C, 1984
- Unklesbay, A.G; & Vineyard, Jerry D. (1992). Missouri Geology — Three Billion Years of Volcanoes, Seas, Sediments, and Erosion. University of Missouri Press. ISBN 0-8262-0836-3.
![[2]](http://commons.wikimedia.org/wiki/File:Precambrian_Granite_St_Francis_Mountains_Missouri.jpg){kind=link}