Missouri River-Osage River drainage divide area landform origins in Cooper, Morgan, and Moniteau Counties, Missouri, USA

Abstract:

Topographic map evidence is used to interpret landform origins in the Missouri River-Osage River drainage divide area in Cooper, Morgan, and Moniteau Counties, Missouri. Four drainage divides are looked at in detail and are the Missouri River-Petite Saline Creek drainage divide, the Petite Saline Creek-Moniteau Creek drainage divide, the Moniteau Creek-North Moreau Creek drainage divide, and the Straight Fork-Little Gravos Creek drainage divide, where Straight Fork is a north-oriented North Moreau Creek tributary and Little Gravos Creek is a south-oriented Osage River tributary and Petite Saline Creek, Moniteau Creek, and North Moreau Creek (which flows to the Moreau River) are east oriented Missouri River tributaries, with the Osage River also being an east and northeast-oriented Missouri River tributary. Topographic map evidence suggests the region was eroded by immense south oriented floods. Headward erosion of the deep Osage River valley first captured the south oriented flood flow and deep south-oriented tributary valleys then eroded headward from the newly eroded Osage River valley north wall. Next North Moreau Creek valley headward erosion beheaded and reversed flood flow to erode north oriented North Moreau Creek tributary valleys and to create the asymmetric North Moreau Creek-Osage River drainage divide. Headward erosion of the Moniteau Creek valley next beheaded and reversed south-oriented flood flow to what were then actively eroding south-oriented North Moreau Creek tributary valleys to create north oriented Moniteau Creek tributary valleys and the Moniteau Creek-North Moreau Creek drainage divide. The Petite Saline Creek-Moniteau Creek and Missouri River-Petite Saline Creek drainage divides were then created in sequence as the Petite Saline Creek valley first eroded headward across the region and then was followed by headward erosion of the deep Missouri River valley.

Preface:

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays available at this site may be found by selecting desired Missouri River tributaries and/or states from this essay’s sidebar category list.

Introduction:

The purpose of this essay is to use topographic map interpretation methods to explore the Missouri River-Osage River drainage divide area landform origins in Cooper, Morgan, and Moniteau Counties, Missouri, USA. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and then by leaving a link to those essays in a comment here.

This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other essays in the Missouri River drainage basin landform origins research project is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.

If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Missouri River-Osage River drainage divide area landform evidence in Cooper, Morgan, and Moniteau Counties, Missouri will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see menu at top of page for paradigm related essay). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Missouri River-Osage River drainage divide area location map

Figure 1: Missouri River-Osage River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 shows a location map for the Missouri River-Osage River drainage divide area in Cooper, Morgan, and Moniteau Counties, Missouri. Missouri is the state occupying much of the figure 1 map area with Illinois being the state located east of the south-southeast oriented Mississippi River, which flows to the figure 1 southeast corner. The Missouri River flows in an east-northeast direction from Kansas City (near figure 1 west edge north of center) to Brunswick and then turns to flow in a southeast, south, east, and southeast direction to Jefferson City. From Jefferson City the Missouri River flows in a northeast, east, southeast, and northeast direction to join the Mississippi River just north of St Louis. The Osage River flows in an east and northeast direction from Schell City (north of figure 1 southwest corner) to Harry S. Truman Reservoir and then to the Lake of the Ozarks. From the Lake of the Ozarks the Osage River flows in a northeast direction to join the Missouri River a short distance downstream from Jefferson City. This Missouri River-Osage River drainage divide area in Cooper, Morgan, and Moniteau Counties, Missouri essay illustrates and describes the region south of the east- and southeast-oriented Missouri River segment located upstream from Jefferson City. Towns included in the Cooper, Morgan, and Moniteau County area discussed here include Boonville, California, Tipton, and Versailles. The Missouri River-Osage River drainage divide area in Moniteau, Cole, and Miller Counties, Missouri essay illustrates and describes topographic map evidence immediately to the east and includes the Jefferson City area. Regional drainage divide area essays are included under the MO Missouri River and/or Osage River categories on the sidebar category list..

Topographic map evidence illustrated in this knob is interpreted in the context of immense south-oriented glacial melt water floods, which flowed across the entire figure 1 map area. This essay only addresses a small region in the figure 1 map area and to fully appreciate the immensity and source of the floods, which crossed the figure 1 map area, it is necessary to look at all Missouri River drainage basin and adjacent region drainage divides, which is the goal of the Missouri River drainage basin landform origins research project, which interprets landform origins for hundreds of Missouri River drainage basin drainage divide areas. Flood waters which flowed across the figure 1 map area were derived from a rapidly melting North American ice sheet, which at the time figure 1 drainage systems evolved was north of figure 1. The ice sheet was located in a deep “hole” created by ice sheet related crustal warping and deep glacial erosion. The Ozark Plateau region south of the figure 1 map area probably was uplifted as crustal warping developed the deep “hole’s” southern rim. However, melt water erosion has also destroyed much of the southern rim evidence. Topographic map evidence from essays describing hundreds of other Missouri River drainage basin drainage divide areas suggests south-oriented flood waters initially over whelmed whatever drainage systems existed and flowed directly to the Gulf of Mexico. This evidence suggests there were no topographic barriers such as the Ozark Plateau and flood waters were free to move south across the entire figure 1 map area. The deep and large Mississippi River valley and its tributary valleys then systematically eroded headward from the Gulf of Mexico to capture the south-oriented flood flow and to divert flood waters to the actively eroding Mississippi River valley system. Mississippi River tributary valley headward erosion occurred in sequence from south to north and west of the Mississippi River also in an east to west sequence. Flood water captures were also aided by Ozark Plateau uplift, which probably occurred as flood waters were flowing across the region.

South of the figure 1 map area, in the state of Arkansas, headward erosion of the southeast-oriented Arkansas River valley and its tributary valleys occurred slightly in advance of headward erosion of the southeast-oriented White River valley and its tributary valleys, which beheaded flood flow routes to the newly eroded Arkansas River valley. South-oriented tributary valleys then eroded headward from the newly eroded White River valley into southern Missouri, just south of the figure 1 map area. Headward erosion of the Missouri River valley and its east and northeast-oriented Osage River tributary valley next beheaded in sequence from east to west the south-oriented flood flow routes to the actively eroding south-oriented White River tributary valleys. Flood waters on north ends of beheaded flood flow routes reversed flow direction to erode north-oriented Missouri River and Osage River tributary valleys. Remember flood flow routes were beheaded in sequence, from east to west, which meant reversed flood flow on a newly beheaded flood flow route could capture yet to be beheaded flood flow from flood flow routes further to the west. These captures of yet to be beheaded flood flow created fascinating flood flow patterns where flood waters were flowing in a north direction adjacent to flood waters flowing in a south direction, and also where flood water was moving in southeast, east, and northeast directions as it proceeded to make giant U-turns in southern Missouri. The massive flood flow reversals responsible for eroding the present day north-oriented Missouri River and Osage River tributary valleys probably were also aided by Ozark Plateau uplift, which probably occurred as the deep Missouri River-Osage River valley eroded headward. Headward erosion of the Missouri River valley and its tributary valleys (upstream from the Jefferson City) proceeded slightly behind Osage River valley headward erosion and beheaded flood flow routes to the newly eroded Osage River valley.

Detailed location map for Missouri River-Osage River drainage divide area

Figure 2: Detailed location map for Missouri River-Osage River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 represents a detailed location map for the Missouri River-Osage River drainage divide area in Cooper, Morgan, and Moniteau Counties, Missouri. County names and boundaries are shown. The Missouri River flows in a southeast, east, southeast, and northeast direction along the northern boundaries of Cooper, Moniteau, Cole, and Osage Counties. The large reservoir along the figure 2 south center edge (along the Morgan County southern border) is the Lake of the Ozarks and is flooding the Osage River valley. Downstream from the Lake of Ozarks the Osage River meanders in a northeast direction from Bagnell Dam (on the Miller County west border) across Miller County and then forms the Cole-Osage County boundary before joining the Missouri River near Osage City. Major Missouri River tributaries of interest in this essay include north, east-northeast, and east oriented Petite Saline Creek in Cooper County; east-oriented Montieau Creek in southeast Cooper County and northern Moniteau County; and east, north, southeast, and east oriented North Moreau Creek in Moniteau County. Straight Fork is a north and northeast-oriented North Moreau Creek tributary originating near Versailles in Morgan County. Little Gravos Creek, which also originates near Versailles flows in a south direction to join the Osage River. Also note the north-oriented Lamine River in western Cooper County and its north-oriented Richland Creek tributary in Morgan County. The Lamine River joins the east-oriented Blackwater River and then flows to the Missouri River in northwest Cooper County. Topographic maps illustrated and described in this essay begin with the Missouri River-Petite Saline Creek drainage divide area near Boonville and then continue to the Petite Saline Creek-Moniteau Creek drainage divide area to the south. Continuing in a south direction the Moniteau Creek-North Moreau Creek drainage divide area is looked at next and finally the Straight Fork-Little Gravos Creek drainage divide area (or North Moreau Creek-Osage River drainage divide) is looked at near Versailles. The topographic map evidence suggests south-oriented flood waters crossed all of the drainage divides with the North Moreau Creek-Osage River drainage divide being created first, the Moniteau Creek-North Moreau Creek drainage divide being created second, the Petite Saline Creek-Moniteau Creek drainage divide being created third, and the Missouri River-Petite Saline Creek drainage divide being created fourth and last. Evidence also suggests north-oriented valleys were eroded by reversals of flood waters on north ends of beheaded south-oriented flood flow routes.

Missouri River-Petite Saline Creek drainage divide area

Figure 3: Missouri River-Petite Saline Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a big picture topographic map of the Missouri River-Petite Saline Creek drainage divide area east of Boonville. Boonville is the town located of the south bank of the Missouri River in the figure 3 northwest corner. The Missouri River flows in an east and southeast direction from Boonville to the figure 3 east edge (south half). Petite Saline Creek flows from the figure 3 west edge (just south of center) in a generally east direction to enter the southeast-oriented Missouri River valley in the figure 3 east center region (near the Cooper-Moniteau County line). Note how Petite Saline Creek has multiple north and north-northwest oriented tributaries from the south and south and southeast oriented tributaries from the north. Also note the Missouri River has short north and north-northwest oriented tributaries from the south. A close look at the Missouri River-Petite Saline Creek drainage divide shows shallow through valleys linking north-oriented Missouri River tributary valleys with south oriented Petite Saline Creek tributary valleys. The map contour interval (south of the Missouri River) is 20 meters and the through valleys are defined by a single contour line on each side (figure 4 provides a detailed topographic map to better illustrate the through valleys). The tributary valley orientations and the through valleys provide evidence of what were once multiple south oriented flood flow channels such as might be found in a south oriented anastomosing channel complex. The south-oriented flood waters were captured by headward erosion of the deep Petite Saline Creek valley, which eroded headward from the actively eroding Missouri River valley head. Headward erosion of the deep Petite Saline Creek valley beheaded south-oriented flood flow channels (in sequence from east to west) and flood waters on north ends of beheaded flood flow channels reversed flow direction to erode north-oriented Petite Saline Creek tributary valleys. Because flood flow channels were beheaded in sequence from east to west reversed flood flow in a newly beheaded flood flow channel could capture yet to be beheaded flood flow from channels further to the west. Such captures of yet to beheaded flood flow account for water volumes required to erode significant north-oriented tributary valleys and also account for east and northeast-oriented tributaries to the north-oriented Petite Saline Creek tributaries. South and southeast-oriented Petite Saline Creek tributary valleys eroded headward along the captured south and southeast-oriented flood flow routes until those flood flow routes were beheaded by Missouri River valley headward erosion, which also reversed flood flow on north ends of beheaded flood flow routes to erode north-oriented tributary valleys.

Detailed map of Missouri River-Petite Saline Creek drainage divide area

Figure 4: Detailed map of Missouri River-Petite Saline Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 depicts a more detailed topographic map of the Missouri River-Petite Saline Creek drainage divide area seen in less detail in figure 3 above. Boonville is located in the figure 4 northwest corner and the Missouri River can be seen along the figure 4 north edge. South-oriented streams flowing to the figure 4 south edge are Petite Saline Creek tributaries and several north-oriented Missouri River tributaries can be recognized. The figure 4 map contour interval is ten feet, which provides much more detail than seen in figure 3. Study of the drainage divide between the north-oriented Missouri River tributaries and the south-oriented Petite Saline Creek tributaries shows numerous shallow through valleys linking north-oriented tributary valleys with south-oriented tributary valleys. Many of these shallow through valleys are defined by only one or two contour lines on each side, although some through valleys are much deeper. For example in the section 5 west center a shallow through valley links a north-northwest oriented Missouri River tributary valley with a south and south-southwest oriented Petite Saline Creek tributary valley. The through valley floor elevation is between 700 and 710 feet in elevation. Elevations rise to more than 760 feet on either side of the through valley (see sections 4 and 9 to the east and the south edge of Boonville to the west), although there are some ups and downs in between higher elevations on either side. Looking at section 5 the first up rises to more than 740 feet and then in the section 5 northeast quadrant is another through valley linking a north-oriented Missouri River tributary valley with the south-southwest oriented Petite Saline Creek tributary valley. This second through valley floor elevation is also between 700 and 710 feet in elevation. These two section 5 through valleys and similar deeper areas between the 760 foot plus high elevations represent channels eroded into the floor of what was once a much broader south-oriented flood flow channel, which was captured by Petite Saline valley headward erosion (south of figure 4). South-oriented tributary valleys then eroded headward along the south-oriented flood flow channel floor into the figure 4 map area until headward erosion of the deep Missouri River valley beheaded the flood flow. Flood waters on north ends of what were then the actively eroding south-oriented Petite Saline Creek tributary valleys reversed flow direction to erode the north-oriented Missouri River tributary valleys. The through valleys represent locations where flood flow channels leading to actively eroding south-oriented Petite Saline Creek tributary valleys were reversed in flow direction and flood waters turned to flow north to the deep Missouri River valley (rather than continuing to flow south).

Petite Saline Creek-Moniteau Creek drainage divide area

Figure 5: Petite Saline Creek-Moniteau Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 shows a big picture topographic map of the Petite Saline Creek-Moniteau Creek drainage divide area south and slightly west of the figure 3 map area. North-oriented streams flowing to the figure 5 north edge are Petite Saline Creek tributaries. Stephens Branch is the north oriented stream flowing near the figure 5 west edge from Bunceton to Speed and then to the north edge (just east of northwest corner). Coalbank Creek is the labeled northwest-oriented Stephens Branch tributary and Tutt Branch is the named southwest oriented Coalbank Branch tributary (and is a barbed tributary). West Branch is the north-northeast oriented stream flowing from near Lone Elm to the figure 5 north center edge and Clark Fork is the north and north-northwest oriented stream directly to the east. Moniteau Creek flows in an east direction along the figure 5 south edge and east of the figure 5 map area enters the southeast-oriented Missouri River valley. Pisgah Creek is the southwest and south oriented stream flowing from near Pisgah to Moniteau Creek in the figure 5 southeast quadrant. Note how the south oriented Pisgah Creek valley is linked with the north-northwest oriented Clark Fork valley by a broad through valley. The map contour interval is 20 meters and the through valley is defined by one contour line on each side. Figure 6 below provides a detailed topographic map of the Clark Fork-Pisgah Creek drainage divide area to better illustrate this through valley. While most other through valleys are not evident in figure 5 note how southeast-oriented Moniteau Creek tributaries are aligned with north- and northwest-oriented Stephens Branch tributaries in the figure 5 southwest quadrant. The alignment of the north-oriented Petite Saline Creek tributaries with the south- and southeast-oriented Moniteau Creek tributaries, plus the through valley linking the Clark Fork and Pisgah Creek valleys and the presence of barbed tributaries, all provide evidence of former south oriented flood flow channels to what was once the newly eroded Moniteau Creek valley and its actively eroding south- and southeast-oriented tributary valleys. Headward erosion of the deep Petite Saline Creek valley north of the figure 5 map area beheaded the south oriented flood flow channels in sequence from east to west. Flood waters on north ends of the beheaded flood flow routes reversed flow direction to erode the north oriented Petite Saline Creek tributary valleys.

Detailed map of Clark Fork-Pisgah Creek drainage divide area

Figure 6: Detailed map of Clark Fork-Pisgah Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed topographic map of the Clark Fork-Pisgah Creek drainage divide area seen in less detail in figure 5 above. Prairie Home is the town located in the figure 6 northeast quadrant. Clark Fork is the north-oriented stream in the figure 6 northwest corner and the northwest-oriented streams in sections 22, 23, 24, and 27 are all Clark Fork tributaries. Pisgah Creek originates in the section 30 northeast corner (near Prairie Home) and flows in a south-southwest, west, and southwest direction into section 36 where it turns to flow in a south-southeast direction to the figure 6 south center edge. Note how in the section 26 east center area a south-southeast oriented Pisgah Creek tributary valley is linked by a through valley with a north-northwest oriented Clark Fork tributary valley. The map contour interval is ten feet and the through valley floor elevation is between 820 and 830 feet. Elevations in the section 35 northwest corner rise to more than 870 feet and near Prairie Home rise to more than 890 feet (slightly south of the figure 6 southwest corner there are elevations rising to more than 890 feet). This through valley provides evidence of a south-oriented flood flow channel to what was once the south-oriented Pisgah Creek valley, which had eroded headward from what was then the newly eroded Moniteau Creek valley north wall. While the channel in section 26 appears narrow, it is really a deeper channel eroded into the floor of what was once a broad south-oriented flood flow channel spanning the entire distance between the 890 feet high elevations previously mentioned (proceeding even further in either direction elevations rise to more than 900 feet along the drainage divide suggesting an even broader flood flow channel once existed). Initially south-oriented flood waters flowed across the entire figure 6 map area on a topographic surface at least as high the highest figure 6 elevations today (i.e. equivalent to the 890-900 foot elevations mentioned). Flood water erosion, which occurred as deep south-oriented Moniteau Creek tributary valleys eroded headward into the figure 6 map area and next as flood flow routes were beheaded in sequence from east to west by headward erosion of the Petite Saline Creek valley, which then resulted in a systematic reversal of flood flow to erode the north-oriented Petite Saline tributary valleys. In other words, the topographic surface seen today was eroded first by south oriented flood waters and then by the reversed flood flow as the Petite Saline Creek valley eroded headward across the region north of figure 6.

Moniteau Creek-North Moreau Creek drainage divide area

Figure 7: Moniteau Creek-North Moreau Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates a big picture topographic map of the Moniteau Creek-North Moreau Creek drainage divide area south of the figure 5 map area and includes overlap areas with figure 5. California is the larger town in the figure 7 southeast quadrant and Tipton is the larger town near the figure 7 west edge. Clarksburg is the smaller town located near the figure 7 center. Moniteau Creek flows in an east direction along the figure 7 north edge. Smiley Creek is a northeast and north-oriented Moniteau Creek tributary originating near Tipton and Howard Creek is a northwest-oriented Smiley Creek tributary. West Brush Creek flows in an east direction north of Clarksburg and then turns to flow in a north direction to join Moniteau Creek. East Brush Creek headwaters are located in and around California and flows in a north and northeast direction to join Moniteau Creek just east of the figure 7 northeast corner. North Moreau Creek flows in an east direction along the figure 7 south center edge and then turns to flow in a north direction before flowing in a south-southeast direction to the figure 7 south edge. South of the figure 7 map area North Moreau Creek flows in a southeast and east-southeast direction with water eventually reaching the Moreau River, which then flows to the Missouri River. Note how most North Moreau Creek tributaries from the north are oriented in southeast and south directions. Through valleys linking the northwest-oriented Howard Creek valley (which drains to Smiley Creek) with the southeast-oriented Dry Fork valley (which drains to the North Moreau Creek valley) can be seen between Tipton and Clarksburg. The map contour interval is 20 meters and the through valleys are defined by one contour line on each side. Through valleys can also be noted in the California area linking north-oriented East Brush Creek headwaters valleys with south-oriented North Moreau Creek tributary valleys, although the urban area obscures some of the evidence. Figure 8 below shows a detailed topographic map of the California region to better illustrate the evidence. The north-oriented North Moreau Creek valley segment was eroded headward along a reversed south-oriented flood flow route. Note how a south-southeast oriented tributary joins North Moreau Creek at the elbow of capture where North Moreau Creek begins to turn from flowing in a north direction to flowing in an east direction just before turning to flow in a south-southeast direction. Also note the south-oriented tributary joining North Moreau Creek where it begins to flow in a south-southeast direction. These two tributaries provide evidence of the south-oriented flood flow channels along which the North Moreau Creek valley first eroded headward to create the south-southeast oriented valley segment and then eroded along the beheaded and reversed western channel to create the north-oriented channel segment. Headward erosion of the Moniteau Creek valley beheaded flood flow to the newly eroded North Moreau Creek valley and its actively eroding tributary valleys and flood waters on north ends of beheaded flood flow routes reversed flow direction to erode the north-oriented Moniteau Creek tributary valleys.

Detailed map of East Brush Creek-North Moreau Creek drainage divide area

Figure 8: Detailed map of East Brush Creek-North Moreau Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 shows a detailed topographic map of the East Brush Creek-North Moreau Creek drainage divide area near California, Missouri. South-oriented streams flowing to the figure 8 south edge are North Moreau Creek tributaries. North-oriented streams originating near California (in sections 27 and 28) and flowing to the figure 8 north edge are East Brush Creek headwaters with East Brush Creek (north of the figure 8 map area) flowing in a north and northeast direction to join Moniteau Creek. The map contour interval is ten feet and note the bench mark (B.M.) indicating an elevation of 915 feet in the section 27 east center area. Proceed west from that bench mark along the East Brush Creek-North Moreau Creek drainage divide westward and note how elevations are below 900 feet until reaching the west center area of section 19 near the figure 8 west edge where 910 foot high elevations are encountered. Also note points along the drainage divide where elevations are lower than adjacent drainage divide locations. For example in the section 19 east center and section 20 west center elevations drop below 880 feet. Elevations less than 880 feet can also be found near the corner of sections 20, 21, 28, and 29 and appear to exist in the California urban area where contour lines are difficult to read. These lower elevation areas along the drainage divide represent locations where south-oriented flood flow channels were eroded into the floor of a much broader south-oriented flood flow channel defined by the 910 foot plus high elevations in section 27 in the east and section 19 in the west. Erosion of the broad south-oriented flood flow channel lowered regional elevations below the 910 foot plus high topographic surface, which flood waters initially flowed upon. Headward erosion of the North Moreau Creek valley south of the figure 8 map area captured the south-oriented flood flow channel and south-oriented tributary valleys eroded headward from the newly eroded North Moreau Creek valley north wall. Flow to these actively eroding tributary valleys became concentrated and eroded even deeper channels into the floor of the broad south-oriented flood flow channel. Headward erosion of the Moniteau Creek valley (north of figure 8) then beheaded the south-oriented flood flow routes in sequence from east to west. Flood waters on north ends of the beheaded flood flow routes reversed flow direction to erode north-oriented tributary valleys, including the north-oriented East Brush Creek valley. The reversal of flood flow, which proceeded from east to west, created the East Brush Creek-North Moreau Creek drainage divide and the figure 8 landscape has changed little since.

Straight Fork-Little Gravos Creek drainage divide area

Figure 9: Straight Fork-Little Gravos Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a big picture topographic map view of the Straight Fork-Little Gravos Creek drainage divide located south and west of the figure 7 map area. Versailles is the largest town seen in the figure 9 map area. Straight Fork flows in a north direction from Versailles to the figure 9 north edge and north of figure 9 turns to flow in a northeast direction to join North Moreau Creek, which east of this essay’s study region joins South Moreau Creek to form the Moreau River (see figure 2). Straight Fork is the westernmost of the north-oriented North Moreau Creek tributaries seen in the figure 9 map area. All north-oriented streams flowing to the figure 9 north edge east of Straight Fork are North Moreau Creek tributaries. North and north-northwest oriented Richland Creek is the stream west of Straight Fork and flows to the figure 9 northwest corner area. North and west of figure 9 Richland Creek flows to the north-oriented Lamine River, which joins the east oriented Blackwater River, and then flows to the southeast-oriented Missouri River in northwest Cooper County (see figure 2). In other words the Richland Creek-Straight Fork drainage divide seen in figure 9 is also the Lamine River-Moreau River drainage divide. Little Gravos Creek originates near Versailles and flows in a south-southeast and south direction to the figure 9 south edge. South of the figure 9 map area Little Gravos Creek flows to the Osage River. All streams flowing to the figure 9 south edge are Osage River tributaries. The drainage divide between the north-oriented Lamine River and North Moreau Creek tributaries and the south-oriented Osage River tributaries is an asymmetric drainage divide, with Osage River tributary valleys being eroded much deep than the north-oriented stream valleys. This asymmetric drainage divide was created when North Moreau Creek (and Lamine River further north) valley headward erosion beheaded and reversed south-oriented flood flow channels moving flood waters to what were then actively eroding south-oriented Osage River tributary valleys. Flood waters on north ends of beheaded flood flow routes reversed flow direction to erode north-oriented valleys. Flood flow routes were reversed in sequence from east to west and reversed flood flow on newly beheaded flood flow routes captured flood waters from yet to be beheaded flood flow routes further to the west. These captures resulted in east and northeast-oriented flood flow movements recorded in east and northeast oriented tributary and headwaters valleys to the north-oriented stream valleys. However, volumes of water eroding north-oriented valleys were significantly smaller than volumes of water which had flowed into the newly eroded and deep Osage River valley. In other words the newly formed north oriented drainage systems were not able to erode as deep as the previous south-oriented flood flow routes moving flood waters to the Osage River valley. The result was the asymmetric drainage divide seen today.

Detailed map of Straight Fork-Little Gravos Creek drainage divide area

Figure 10: Detailed map of Straight Fork-Little Gravos Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Straight Fork-Little Gravos Creek drainage divide area seen in less detail in figure 9. Versailles is the town in the figure 10 southwest quadrant. Straight Fork is the stream flowing in a north direction in sections 36 and 25 north of Versailles. The north-northwest oriented stream in section 29 is a Straight Fork tributary. North of the figure 10 map area Straight Fork flows to North Moreau Creek. The southeast-oriented stream in section 34 flowing to the figure 10 east center edge is the headwaters of Burris Fork, which east of the figure 10 map area turns to flow in a northeast direction (with many twists and turns) to eventually join North Moreau Creek, which then flows to the Moreau River. The south-oriented streams in section 5 are Little Gravos Creek headwaters and other south-oriented streams flowing to the figure 10 south edge are Little Gravos Creek tributaries. South of the figure 10 map area Little Gravos Creek flows to the Osage River. The asymmetric North Moreau Creek-Osage River drainage divide is easily recognized, with the south-oriented Little Gravos Creek drainage basin being eroded much deeper than the north-oriented North Moreau Creek drainage basin. A close look at the drainage divide reveals through valleys eroded across it, providing evidence of south-oriented flood flow channels which once crossed the entire figure 10 map area. South and west of Versailles elevations along the drainage divide rise to more than 1100 feet although at the County Fairgrounds west of Versailles (seen near the figure 10 west edge) elevations rise only to between 1030 and 1040 feet (the map contour interval is ten feet). In the section 31 southeast quadrant east of Versailles elevations along the drainage divide drop to between 1000 and 1010 feet. With some minor ups and downs elevations do not rise much until reaching the section 33 northeast corner and the section 28 southeast quadrant where elevations rise to at least 1070 feet. This “sag” in the present day North Moreau Creek-Osage River drainage divide was eroded by a south-oriented flood flow channel to what was then the actively eroding south-oriented Little Gravos Creek valley system, which was eroding headward from the newly eroded and deep Osage River valley. Headward erosion of the North Moreau Creek valley north of the figure 10 map area beheaded the south-oriented flood flow channel. Flood waters on the north end of the beheaded flood flow channel reversed flow direction to erode the north-oriented Straight Fork valley (and tributary valleys) and to create the Straight Fork-Little Gravos Creek drainage divide.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.