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''Physiographic map of Missouri ( Legend )
Courtesy USGS'' |
Missouri , a state near the geographical center of the
United States , has
Three Distinct Physiographic Divisions :
- a north-western upland plain or prairie region part of the Interior Plains' Central Lowland ( Areas Osage Plain 12f And Dissected Till Plains 12e ) known as the northern plains
- a lowland in the extreme southeast Bootheel region of Missouri, part of the Atlantic Plain known as the Mississippi Alluvial Plain ( Areas 3e ) or the Mississippi Embayment
- the Missouri portion of the Ozark Plateau (areas 14a and 14b) which lies between the Mississippi Alluvial Plain and the Central Lowland.
The boundary between the northern plains and the Ozark region follows the
Missouri River from its mouth at
St. Louis to
Columbia . This also corresponds to the southernmost extent of the severe
Kansan Glaciation which destroyed the remnant plateau to the north but left the ancient landforms to the south unaltered. The Ozark boundary runs southwestward from there towards
Joplin at the southeast corner of
Kansas . The boundary between the Ozark and lowland regions runs southwest from
Cape Girardeau on the
Mississippi River to the
Arkansas border just southwest of
Poplar Bluff .
The Dissected
Till Plains portion of the northern plains region lies in the portion of the state north of the
Missouri River , while the Osage plains portion extends into the southwestern portion of the state bordering the Ozark Plateau. Thus the northern plains covers an area slightly more than a third of the state. This region is a beautiful, rolling country, with a great abundance of streams.
It is more hilly and broken in its western half than in its eastern half. The elevation in the extreme northwestern Missouri is about 1,200 ft. and in the extreme northeastern portion about 500 ft., while the rim of the region to the southeast, along the border of the Ozark region, has an elevation of about 900 ft. The valleys for the larger streams are about 250 to 300 ft. deep and sometimes 8 to 20 miles wide with the country bordering them being the most broken of the region.
The smaller streams have so eroded the whole face of the country that little of the original surface plain is to be seen. The
Mississippi River runs along the length of Missouri's eastern side and is skirted throughout by topographic relief of 400 to 600 ft. elevation.
The Ozark region is essentially a low dome, with local faulting and minor undulations, dominated by a ridge or, more exactly, a relatively
even belt of highland that runs from near the Mississippi river about
Ste. Genevieve to
McDonald County on the Arkansas border. High rocky bluffs rise precipitously on the Mississippi, sometimes to a height of 150 ft. or so above the water, from the mouth of the
Meramec River to Ste. Genevieve. These mark where that river cuts the Ozark ridge. Across the Mississippi River, this ridge is continued by the Shawnee Hills in Illinois.
The elevations of the crests in Missouri (the highest portions of the Ozarks are in the
Boston Mountains of Arkansas) vary from 1,100 to 1,700 ft. This second physiographic region comprises somewhat less than two-thirds of the area of the state. The Burlington escarpment of
Mississippian rocks, which in places is as much as 250 to 300 ft. in height, runs along the western edge of the
Ordovician formations and divides the region into an eastern and a western area, known respectively to physiographers as the Salem Plateau and the Springfield Plateau. Headward erosion by the south flowing tributaries to the
White River in northern Arkansas has created a southern escarpment to both the Springfield and Salem plateaus that runs from
McDonald through Barry, Stone, Christian, Douglas, and Howell counties. To the south of this escarpment lies some of the more rugged and highly dissected parts of the Missouri Ozarks. The famed
Shepherd Of The Hills region near
Branson lies within this rugged area. To the east of the
West Plains plain lies the dissected valleys of the
Eleven Point River and the
Current River .
Superficially, each is a simple rolling plateau, much broken by erosion (though considerable undissected areas drained by underground channels remain), especially in the east, and dotted with hills. Some of these are residual outliers of the eroded
Mississippian Limestone s to the west, and others are the summits of a
Precambrian topography above and around which
Sedimentary formations were deposited and then eroded. There is no arrangement in chains, but only scattered rounded peaks and short ridges, with winding valleys about them.
The two highest points in the state are
Taum Sauk Mountain at 1772 ft., in the
St. Francis Mountains in
Iron County and Lead Hill just east of the community of
Cedar Gap at 1744 ft., in the southwestern corner of
Wright County .
Few localities have an elevation exceeding 1,400 ft. Rather broad, smooth valleys, well degraded hills with rounded summits, and despite the escarpments generally smooth contours and sky-lines, characterize the bulk of the Ozark region.
The third region, the lowlands of the south-east and part of the Mississippi Alluvial Plain, has an area of some 3,000 mile
2. It is an undulating country, for the most part well drained, but swampy in its lowest portions. The Mississippi is skirted with lagoons, lakes and morasses from Ste. Genevieve to the
Arkansas border, and in places is confined by levees. These lowlands are the northernmost extent of the
Mississippi Embayment . The area is within the
New Madrid Seismic Zone and includes the
Epicenter location of the
1811 -
1812 New Madrid Earthquake at
New Madrid, Missouri .
The drainage of the state is wholly into the
Mississippi River , directly or indirectly, and almost wholly into either that river or the
Missouri River within the borders of the state. The latter stream, crossing the state and cutting the eastern and western borders at or near St Louis and Kansas City respectively, has a length within Missouri of 430 miles.
The areas drained into the Mississippi outside the state through
the
St. Francis ,
White and other minor streams are relatively small. The larger streams of the
Ozark dome are of decided interest to the physiographer. Those of the
White system have opentrough valleys bordered by hills in their
upper courses and canyons in their lower courses.
Both the Ozark region and the northern plain region are divided by minor
escarpments into ten or twelve sub-regions. There are remarkable differences in the drainage areas of their two sides, with interesting illustrations of shifting water-partings; and the White, Gasconade, Osage and other rivers are remarkable for upland meanders, lying, not on flood-plains, but around the spurs of a highland country. These
Incised Meander s have been interpreted to have formed by downward erosion after uplift of an older
Peneplain surface.
Many streams in Missouri are called "rivers" even though they would seem to be rather small and perhaps should be called "creeks". This is due to a direct translation of the French word "rivière" which implies a stream size smaller than the French word "fleuve", meaning "a river that flows to the sea". An example of this is "Loutre River", from "Rivière Loutre", or "Otter Stream".
The Ozarks region is noted for having a well developed
Karst topography with numerous areas of
Sinkhole s, stream capture, and
Cavern development.
Caves, within areas of
Limestone and
Dolostone bedrock, occur in great numbers in and near the Ozark Mountain region in the southwestern part of Missouri. More than a hundred have been discovered in
Stone County alone, and there are many in
Christian ,
Greene and
McDonald counties.
One of the most remarkable is
Marble Cave , a short distance
southeast of the center of Stone county. The entrance originally was through a large sink-hole at the top of Roark Mountain, though now an easier entrance has been made. Marble Cave has an extraordinary hall-like room is about 350 ft. long and about 125 ft. wide with bluish-grey limestone walls, and an almost perfectly vaulted roof, rising from 100 to 295 ft. Its acoustic properties are said to be almost perfect, and it has been named the Auditorium. At one end is a remarkable stalagmitic formation of white and gold onyx, about 65 ft. in height and about 200 ft. in girth, called the White Throne.
Exploration of Jacob's Cavern, near
Pineville ,
McDonald county, reveled skeletons of men and animals along with rude implements. Crystal Cave, near Joplin,
Jasper county, has its entire surface lined with
Calcite crystals and scalenohedron formations, from 1 to 2 ft. in length. Knox Cave, in
Greene county, and several caverns near Ozark, in
Christian county, are also of interest. Other caves include Fried's Cave,
about six miles northeast of
Rolla ,
Phelps county, Mark Twain Cave (in
Marion county, about one mile south of
Hannibal ), which has a deep pool containing many eyeless fish; and various caverns in
Miller ,
Ozark ,
Greene and
Barry counties.
- 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.
