Editing Geography of Missouri (section)

==Regions==

=== Northern Plains ===
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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 {{convert|1200|ft|m|abbr=on}}. and in the extreme northeastern portion about {{convert|500|ft|m|abbr=on}}., while the rim of the region to the southeast, along the border of the Ozark region, has an elevation of about {{convert|900|ft|m|abbr=on}}. The valleys for the larger streams are about 250 to {{convert|300|ft|m|abbr=on}} deep and sometimes 8 to {{convert|20|mi|km}} 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 {{convert|600|ft|m|abbr=on}}. elevation.

=== Ozark Plateau ===
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The [[Ozarks]] 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 County, Missouri|Ste. Genevieve]] to [[McDonald County, Missouri|McDonald County]] on the Arkansas border. High rocky bluffs rise precipitously on the Mississippi, sometimes to a height of {{convert|150|ft|m|abbr=on}} 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. 
[[File:Roubidoux sandstone bluff.JPG|thumb|The sandstone member of the Ordovician [[Roubidoux Formation]] outcrops along many bluffs of the southern Ozarks]]
The elevations of the crests in Missouri vary from 1,100 to {{convert|1700|ft|m|abbr=on}}. This second physiographic region comprises somewhat less than two-thirds of the area of the state. The Burlington [[escarpment]] of [[Mississippian age|Mississippian]] rocks, which in places is as much as 250 to {{convert|300|ft|m|abbr=on}} 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 (Arkansas)|White River]] in northern Arkansas has created a southern escarpment to both the Springfield and Salem plateaus that runs from [[McDonald County, Missouri|McDonald]] through [[Barry County, Missouri|Barry]], [[Stone County, Missouri|Stone]], [[Christian County, Missouri|Christian]], [[Douglas County, Missouri|Douglas]], and [[Howell County, Missouri|Howell]] counties. To the south of this escarpment lies some of the more rugged and highly dissected parts of the Missouri Ozarks. The famed [[The Shepherd of the Hills (novel)|Shepherd of the Hills]] region near [[Branson, Missouri|Branson]] lies within this rugged area. To the east of the [[West Plains, Missouri|West Plains]] plain lies the dissected valleys of the [[Eleven Point River]] and the [[Current River (Ozarks)|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 age|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 {{convert|1772|ft|m|abbr=on}} in the [[Saint Francois Mountains|St. Francois Mountains]] in [[Iron County, Missouri|Iron County]] and Lead Hill just east of the community of [[Cedar Gap, Missouri|Cedar Gap]] at {{convert|1744|ft|m|abbr=on}} in the southwestern corner of [[Wright County, Missouri|Wright County]]. 
Few localities have an elevation exceeding {{convert|1400|ft|m|abbr=on}}. 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.

=== Mississippi Alluvial Plain ===
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The third region, the lowlands of the south-east and part of the Mississippi Alluvial Plain, has an area of some {{convert|3000|sqmi|km2|adj=on}}. 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 [[1811–12 New Madrid earthquakes]] at [[New Madrid, Missouri]].