Abstract:

The Niangua River-Osage Fork (Gasconade River) drainage divide area in Dallas, Laclede, and Webster Counties, Missouri is the drainage divide between a north-oriented Osage River tributary to the west and a northwest and northeast oriented Gasconade River tributary to the east and was eroded by immense south-oriented floods which were beheaded and reversed by headward erosion of deep east and northeast oriented Missouri River tributary valleys. Headward erosion of the deep northeast-oriented Osage Fork (Gasconade River) valley from what were then newly eroded Gasconade and Missouri River valleys beheaded and reversed southeast oriented flood flow to trigger a flood flow reversal that eroded the northwest-oriented Osage Fork (Gasconade River) headwaters valley. Southeast-oriented flood flow routes beheaded by headward erosion of the deep Osage Fork valley had been moving flood water to what was then the newly eroded Gasconade River valley south and east of the actively eroding Osage Fork valley. Osage Fork (Gasconade River) valley headward erosion captured significant flood flow which had been moving south in the present day north-oriented Niangua River drainage basin. The captured flood flow moved in southeast, and east directions to the actively eroding Osage Fork valley. South-oriented flood flow in the present day north-oriented Niangua River drainage basin was beheaded by headward erosion of the deep east and northeast oriented Osage River valley from what was then the newly eroded Missouri River valley. Flood waters on the north end of the beheaded flood flow routes reversed flow direction to erode the deep north-oriented Niangua River valley and also to reverse flood waters on northwest and west ends of what had been southeast and east-oriented flood flow routes to the newly eroded Osage Fork (Gasconade River) valley. The reversals of flood flow eroded west and northwest oriented Niangua River tributary valleys. Evidence supporting this flood origin interpretation includes positions and orientations of present day valleys and through valleys eroded across the present day Niangua River-Osage Fork (Gasconade River) drainage divide.

Preface:

The following interpretation of detailed topographic map evidence is provided as evidence in the Missouri River drainage basin landform origins research project, which is compiling similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with and within certain adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored geomorphology paradigm, which is briefly described in the introduction below. 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.

• The purpose of this essay is to use topographic map interpretation methods to explore Niangua River-Osage Fork (Gasconade River) drainage divide area landform origins in Dallas, Laclede, and Webster 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 the 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 topographic map evidence in the Niangua River-Osage Fork (Gasconade River) drainage divide area in Dallas, Laclede, and Webster Counties, Missouri will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see menu at top of page for a paradigm related essay).

Niangua River-Osage Fork (Gasconade River) drainage divide area location map

Figure 1: Niangua River-Osage Fork (Gasconade 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 provides a location map for the Niangua River-Osage Fork (Gasconade River) drainage divide area located in Dallas, Laclede, and Webster Counties, Missouri and illustrates most of southern Missouri with a thin strip of northern Arkansas in the south and a small region of western Illinois in the northeast corner area. The Mississippi River flows in a south and southeast direction from St Louis near the northeast corner to the figure 1 east edge and forms the Missouri-Illinois boundary. The Missouri River flows from near Jefferson City, Missouri (near figure 1 north center edge) in an east direction to join the south-oriented Mississippi River a short distance north of St. Louis. The Gasconade River is a northeast-oriented Missouri River tributary originating east of Springfield near Seymour in the figure 1 southwest quadrant and joining the Missouri River midway between Jefferson City and Washington, Missouri. The Osage Fork (Gasconade River) is a Gasconade River tributary originating a short distance north of the Gasconade River headwaters near Seymour and flowing in a north and northeast direction to join the Gasconade River north and east of Lebanon, Missouri. The Osage River is an east and northeast oriented Missouri River tributary formed by the confluence of tributaries near Schell City (near west edge in figure 1 northwest quadrant) and flowing in an east direction to Harry S. Truman Reservoir and then to the Lake of the Ozarks before turning to flow in a northeast direction to join the Missouri River near Jefferson City. The Niangua River is a north-oriented Osage River tributary originating near Marshfield (north of Seymour) and joining the Osage River at the Lake of the Ozarks. The Niangua River-Osage Fork (Gasconade River) drainage divide area in Dallas, Laclede, and Webster Counties is located between the north-oriented Niangua River to the west and the north-oriented Osage Fork (Gasconade River) to the east and south of Lebanon, Missouri to the north and north of Seymour, Missouri to the south and was eroded by an immense south-oriented flood, which was systematically reversed by headward erosion of the deep east-oriented Missouri River valley and its tributary Gasconade River-Osage Fork valley and Osage River valley to become a massive north-oriented flood flow. Flood waters were beheaded and reversed in sequence from east to west and the reversed flood flow routes eroded deep north-oriented valleys. The deep north-oriented valleys captured flood flow still moving south further to the west. The Pomme de Terre River-Niangua River drainage divide area in Polk, Dallas, and Webster Counties essay describes flood flow reversal processes in the region immediately west of the Niangua River-Osage Fork (Gasconade river) drainage divide area and can be found under Osage River on the sidebar category list.

Niangua River-Osage Fork (Gasconade River) drainage divide area detailed  location map

Osage Fork (Gasconade River)-James River drainage divide area

Figure 3 illustrates the Osage Fork (Gasconade River)-James River drainage divide area in Webster County. Diggins is the small town in the southwest corner area. High Prairie is the small town located near the figure 3 north center edge. New Grove is the town in the figure 3 east center area. Waldo is a small town located in the figure 3 south center area. The Osage Fork (Gasconade River) originates south of High Prairie and flows in a north and northwest direction to the figure 3 north edge. North of the figure 3 map area the Osage Fork turns to flow in a northeast direction to eventually join the Gasconade River. The northeast-oriented stream at New Grove is Woods Fork (Gasconade River) and it joins southeast oriented Bowman Creek at the figure 3 east edge. East of the figure 3 map area the Woods Fork (Gasconade River) flows in an east-southeast direction before joining the northeast-oriented Gasconade River. Gasconade River headwaters are located in the figure 3 southeast quadrant and flow in a southeast and east direction to the figure 3 southeast corner. East of the figure 3 southeast corner the Gasconade River turns to flow in a northeast, north-northeast, and north direction and eventually joins the east-oriented Missouri River. The James River originates a short distance east of Waldo near the Gasconade River headwaters and first flows in a south direction before turning to flow in a west and northwest direction to the figure 3 west edge (slightly north of the center). West of the figure 3 map area the James River turns to flow in a southwest direction and then south direction to eventually join the southeast-oriented White River. The Gasconade River-James River drainage divide shown in figure 3 is the drainage divide between the Missouri River drainage basin to the north and east and the White River drainage to the south and west. Study of the figure 3 map area reveals shallow through valleys linking the diverging drainage routes including the west oriented James River valley and the east- and north-oriented Gasonade River and Osage Fork valleys. The through valleys are best seen on more detailed topographic maps and figure 4 below provides a detailed map of the Teague Creek-Osage Fork (Gasconade River) drainage divide area south of High Prairie. Teague Creek is a west oriented James River tributary in the figure 3 west center area. Figure 3 valleys were eroded by an immense south-oriented flood that flowed across the entire region. Initially flood waters moved south across the entire figure 3 map area on a topographic surface at least as high as the highest figure 3 elevations today. Flood waters at that time were flowing to what was then the newly eroded White River valley located south of the figure 3 map area. Headward erosion of the deep Gasconade River valley and its deep tributary Woods Fork and tributary valleys captured the flood flow in the figure 3 east half and also captured flood flow from south-oriented flood flow routes further to west. Captured flood flow moving to the actively eroding Gasconade River valley moved in a southeast and east direction along what are now the northwest-oriented Osage Fork (Gasconade River) and James River alignments. Headward erosion of the deep northeast-oriented Osage Fork (Gasconade River) valley north of the figure 3 map area beheaded and reversed southeast-oriented flood flow on what is now the northwest-oriented Osage Fork alignment. Headward erosion of the south-oriented James River valley (from the actively eroding White River valley) beheaded the southeast- and east-oriented flood flow route causing a flood flow reversal that eroded the west- and northwest-oriented James River valley.

Detailed map of Teague Creek-Osage Fork (Gasconade River) drainage divide area

Figure 4: Detailed map of Teague Creek-Osage Fork (Gasconade River) drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed map to illustrate the Teague Creek-Osage Fork (Gasconade River) drainage divide area seen in less detail in figure 3 above. Teague Creek flows in a west direction along the west half of the figure 4 south edge and west of the figure 4 southwest corner joins northwest-oriented James River. Today the James River after flowing in a northwest direction turns to flow in a southwest and south direction to join the southeast-oriented White River. The north-oriented Osage Fork (Gasconade River) headwaters are located in section 26 near the figure 4 north edge and north of the figure 4 map area the Osage Fork turns to flow in a northwest direction before turning again to flow in a northeast direction. The Teague Creek-Osage Fork drainage divide is the divide between the Missouri River drainage basin to the north and the White River drainage basin to the south. Note the south-southwest to north-northeast oriented through valley in section 4 linking a south-southwest oriented Teague Creek tributary valley with a north-northeast oriented Osage Fork tributary valley. Study of the figure 4 map area reveals multiple through valleys at various elevations, although the section 4 through valley is the deepest. The through valley floor elevation at the drainage divide is between 1580 and 1590 feet (the map contour interval is ten feet). The hill immediately to the west in section 4 rises to at least 1650 feet and a hill in section 3 rises to at least 1660 feet suggesting the through valley is at least 60-80 feet deep. The through valley is a water eroded feature and was eroded by flood waters captured from west of the figure 4 map area which moved in a southeast, east, and north-northeast direction to what was then the newly eroded and actively eroding north-oriented Osage Fork valley. Flood waters were moving southeast on what is now the northwest James River alignment, east on what is now the west-oriented Teague Creek alignment, and north-northeast in what is now the through valley. Headward erosion of the deep south-oriented James River valley west of the figures 3 and 4 map area beheaded the southeast-oriented flood flow on the present day northwest-oriented James River alignment. Flood waters on the northwest end of the beheaded flood flow route reversed flow direction to erode the northwest-oriented James River valley and the west-oriented Teague Creek valley. The northwest-oriented Osage Fork valley north of the figure 4 map area was also initiated as a southeast-oriented flood flow route to what was then the actively eroding Gasconade River valley located south and east of the figure 4 map area. Headward erosion of the deep northeast-oriented Osage Fork valley north and west of the figure 4 map area beheaded and reversed that flood flow route to erode the northwest-oriented Osage Fork valley.

East Branch Niangua River-Osage Fork (Gasconade River) drainage divide area

Figure 5: East Branch Niangua River-Osage Fork (Gasconade River) drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the East Branch Niangua River-Osage Fork (Gasconade River) drainage divide area located north of the figure 3 map area. Marshfield is the larger town located in the figure 5 southwest quadrant. Niangua is the somewhat smaller town located slightly east of the figure 5 center. The Osage Fork (Gasconade River) flows in a northwest direction from the figure 5 south edge (east half) and then turns to flow in a north-northeast direction to the figure 5 north edge near the northeast corner. Cantrell Creek is the north-oriented Osage Fork tributary flowing along the figure 5 east edge. Hannah Branch is the northeast-oriented Osage Fork tributary in the figure 5 south center edge area. Note southeast and northeast oriented Bowen Creek in the figure 5 northeast quadrant which flows to the northeast-oriented Osage Fork. The East Branch Niangua River originates in the region between Marshfield and Niangua and flows in a north-northwest direction to join the north-northwest and north oriented West Fork Niangua River near the figure 5 north edge. North of the figure 5 map area the Niangua River flows in a north direction to eventually reach the east and northeast oriented Osage River. The West Fork Niangua River originates just north of Marshfield and flows in a north-northwest and north direction to join the East Fork Niangua River near the figure 5 north edge. The southwest oriented stream flowing from Marshfield to the figure 5 southwest corner is the Pomme de Terre River, which also originates near Marshfield. South and west of the figure 5 map area the Pomme de Terre River parallels a southwest oriented James River tributary, which joins the James River near the point where the James River turns from flowing in a northwest direction to flowing in a southwest direction (the James River eventually flows to the southeast oriented White River). The Pomme de Terre River north of that point turns from flowing in a southwest direction to flowing in a northwest direction and later turns to flow in a north direction to join the east and northeast-oriented Osage River, which joins the east-oriented Missouri River. Note how the north-northwest oriented East Branch Niangua River alignment is approximately the same as the northwest oriented Osage Fork headwaters. Also note in the figure 5 north center area northwest oriented Sarah Branch which is linked by a through valley with the southeast- and northeast-oriented Bowen Creek valley (figure 6 below provides a detailed map to better illustrate that region). Northwest-oriented valleys were eroded by a reversal of southeast-oriented flood flow routes moving flood waters to what were then actively eroding Gasconade River and tributary valleys located south and east of the figure 5 map area. Headward erosion of the deep Osage Fork (Gasconade River) valley first beheaded and reversed the southeast-oriented flood flow. Next headward erosion of the deep Missouri River-Osage River valley north of the figure 5 map area beheaded and reversed flood flow on the Niangua River alignment to erode the deep north-oriented Niangua River valley and its northwest-oriented tributary valleys. Flood waters still moving south on the present day Pomme de Terre River alignment west of the actively eroding Osage River valley then moved south, southeast, northeast, and north to the actively eroding north-oriented Niangua River valley. Headward erosion of the deep Osage River valley then beheaded and reversed flood flow on the Pomme de Terre River alignment and reversed flood flow eroded the southwest-, northwest-, and north-oriented Pomme de Terre River valley.

Detailed map of Sarah Branch-Bowen Creek drainage divide area

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

Figure 6 provides a detailed map of the Sarah Branch-Bowen Creek drainage divide area seen in less detail in figure 5 above. Niangua is the town located along the figure 6 south edge. The Osage Fork (Gasconade River) can be seen in the figure 6 southeast corner and flows in a north direction east of the figure 6 east edge and the Osage Fork valley can again be seen in the figure 6 northeast corner. North and east of the figure 6 northeast corner the Osage Fork flows in a northeast direction (see figure 5 above). Sarah Branch originates in section 7 and flows in a northwest direction to the figure 6 west edge (near northwest corner). West and north of the figure 6 map area Sarah Branch flows to the north-oriented Niangua River, which then flows to the east and northeast oriented Osage River. Bowen Creek also originates in section 7 and flows in a southeast direction to section 16 where it turns to flow in a northeast direction to the figure 6 northeast corner area. North and east of the figure 6 northeast corner Bowen Creek joins the north-northeast oriented Osage Fork (Gasconade River), which flows to the Gasconade River, which in turn flows to the Missouri River. Note the northwest-southeast oriented through valley in section 7 linking the northwest-oriented Sarah Branch valley with the southeast oriented Bowen Creek valley. Disregarding the railroad embankment the through valley floor elevation at the drainage divide is between 1330 and 1340 feet. Hills north of the through valley rise to an elevation of at least 1420 feet and hills south of the through valley rise to elevations greater than 1450. The through valley is a water eroded feature and was eroded by south oriented flood water moving south on what is now the north-oriented Niangua River alignment, southeast on what is now the northwest-oriented Sarah Branch alignment and then southeast and northeast on the Bowen Creek alignment to what was then the newly eroded and actively eroding northeast-oriented Osage Fork Gasconade River valley, which had eroded headward from what were then newly eroded Gasconade and Missouri River valleys. At that time the deep Osage River valley had not eroded headward north of the figure 6 map area. Headward erosion of the deep Osage River valley north of the figure 6 map area occurred after headward erosion of the Osage Fork (Gasconade River) valley had captured south oriented flood flow on the present day Niangua River alignment and had begun to erode a south, southeast, and northeast oriented valley headward along the present day Bowen Creek, Sarah Branch, and Niangua River alignments. Headward erosion of the deep Osage River valley beheaded south oriented flood to the south, southeast, and northeast oriented Niangua River-Sarah Branch-Bowen Creek flood flow route. Flood waters on the north and northwest end of the beheaded flood flow route reversed flow direction to erode the north-oriented Niangua River valley and the northwest-oriented Sarah Branch valley and to create the Sarah Branch-Bowen Creek drainage divide which is also the Osage River-Gasconade River drainage divide.

Jones Creek-Salem Springs Creek drainage divide area

Figure 7: Jones Creek-Salem Springs Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Jones Creek-Salem Springs Creek drainage divide area located north of the figure 5 map area. Conway is the town located east of the figure 5 south center and Phillipsburg is the town located near the figure 5 east center. The Niangua River flows in a north-northwest direction across the figure 7 southwest corner. West of the figure 5 map area the Niangua River turns to flow in more of a north oriented direction just west of the figure 7 map area and then turns to flow in an east direction north of the figure 7 map area before turning again to flow in a north direction north of the figure 7 center area. West, northwest, and north oriented streams in the figure 7 west half are all Niangua River tributaries. Jones Creek originates near Conway and flows in a northwest, southwest, and west direction to join the Niangua River near the figure 7 west edge (north of southwest corner). Dousinbury Creek originates north of Phillipsburg and flows in a west-northwest, west, southwest, west, north, and west direction to figure 7 west edge (south of northwest corner) and joins the Niangua River west of the figure 7 northwest corner. The Osage Fork (Gasconade River) flows in a northeast direction across the figure 7 southeast corner. Salem Springs Creek is a Osage Fork (Gasconade River) tributary originating near Conway and joining the Osage Fork in the figure 7 southeast corner area. Brush Creek is a southeast and east oriented Osage Fork tributary located in the figure 7 east center area east of Phillipsburg. Note how northwest oriented Jones Creek headwaters originate near where the southeast-oriented Salem Springs Creek headwaters originate. Also note northwest-oriented Dousinbury Creek tributaries and valley segments located on approximately the same northwest-southeast alignment as the alignment of the Jones Creek headwaters and the Salem Springs Creek headwaters. A close look at the figure 7 reveals shallow through valleys linking some of these northwest-southeast oriented valley segments. The through valleys provide evidence of flood flow channels, which captured south-oriented flood flow which had been moving south in the present day north-oriented Niangua River drainage basin and diverted that flood flow in a southeast direction to what was then the actively eroding and deep northeast-oriented Osage Fork (Gasconade River) valley. The southeast-oriented flood flow channels were dismembered by headward erosion of deep tributary valleys during the reversal of flood flow in what is now the north-oriented Niangua River drainage basin. Reversal of flood flow in the Niangua River drainage basin occurred when headward erosion of the deep east and northeast-oriented Osage River valley north of the figure 7 map area beheaded south-oriented flood flow routes and caused the deep north -oriented Niangua River valley and its tributary valleys to erode headward from the newly eroded and deep Osage River valley.

Detailed map of Jones Creek-Salem Springs Creek drainage divide area

Figure 8: Detailed map of Jones Creek-Salem Springs Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed map of the Jones Creek-Salem Springs Creek drainage divide area near Conway seen in less detail in the figure 7 map area above. Conway is the town located just east of the figure 8 south center. Jones Creek originates a short distance south and west of Conway and flows in a north direction along the west side of Conway before turning to flow in a northwest direction to the figure 8 northwest corner area. West of the figure 8 map area Jones Creek turns to flow in a southwest and west direction to join the north-oriented Niangua River. Salem Springs Creek originates in the southeast corner of section 5 (north and east of Conway) and flows in an east and southeast direction to the figure 8 east edge (slightly south of the center). East of the figure 8 map area Salem Springs Creek flows to the northeast-oriented Osage Fork (Gasconade River). Just north of Conway in sections 8 and 9 there is a west to east oriented through valley (now crossed by the railroad) linking a west-oriented Jones Creek tributary valley with an east oriented Salem Springs Creek tributary valley. The through valley floor elevation at the drainage divide appears to be between 1380 and 1390 feet (the map contour interval is ten feet). Following the drainage divide in a northeast direction leads to elevations in excess of 1440 feet (and just north of the figure 8 map area to elevations in excess of 1450 feet). Elevations greater than 1450 feet are found along the drainage divide at the figure 8 south edge. The through valley is a water eroded feature and was eroded by southeast-oriented flood flow captured from south oriented flood flow on the present day north-oriented Niangua River alignment which was moving to what was then the actively eroding northeast-oriented Osage Fork (Gasconade River) valley located south and east of the figure 8 map area. At that time the deep north-oriented Niangua River valley did not exist nor did the deep Osage River valley north of the figure 8 map area exist. Headward erosion of the deep east and northeast-oriented Osage River valley north of the figure 8 map area beheaded the south and southeast oriented flood flow route across the figure 8 map area (and many other south oriented flood flow routes as well). Flood waters on north ends of beheaded flood flow routes reversed flow direction to erode the deep north-oriented Niangua River valley and flood waters on southwest and west ends of south-, southeast, and east-oriented flood flow routes to the newly eroded Osage Fork (Gasconade River) valley reversed flow direction to erode deep northwest and west oriented Niangua River tributary valleys and to create the Niangua River-Osage Fork drainage divide.

Spring Hollow-Brush Creek drainage divide area

Figure 9: Spring Hollow-Brush Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Spring Hollow-Brush Creek drainage divide area north and slightly east of the figure 7 map area and includes overlap areas with figure 7. Lebanon is the large town located in the figure 9 northeast corner. Phillipsburg is the smaller town located near the figure 9 south center edge. The Niangua River flows in a north direction west of the figure 9 map area and then turns to flow in an east direction in the figure 9 northwest corner. From the figure 9 northwest corner the Niangua River flows in a north direction to join the east and northeast oriented Osage River, which in turn flows to the east oriented Missouri River. Spring Hollow is the northwest-oriented valley originating north of Phillipsburg and draining to the north-oriented Niangua River north of the figure 9 map area. Dousinbury Creek is the west-oriented Niangua River tributary located in the figure 9 southwest quadrant. The northeast-oriented Osage Fork (Gasconade River) is located south and east of the figure 9 map area. Brush Creek is the southeast-oriented stream flowing to the figure 9 south edge east of Phillipsburg and south and east of the figure 9 map area flows in an east-northeast and east-southeast direction to join the Osage Fork. North-oriented drainage in the figure 9 northeast quadrant flows to north-oriented Dry Auglaize Creek, which flows to the east-oriented Osage River. The Osage River-Dry Auglaize Creek drainage divide area in Camden, Miller, and Laclede Counties essay describes the region directly north and east of figure 9 (see essay list under Osage River on sidebar category list). Note how the northwest-oriented Spring Hollow alignment is almost the same as the southeast-oriented Brush Creek alignment. Also note the presence of shallow northwest-southeast oriented through valleys linking valleys of northwest-oriented Spring Hollow headwaters with valleys of southeast-oriented Brush Creek headwaters. The similarity of alignments and the shallow through valleys provide evidence of former southeast-oriented flood flow channels to what was then the actively eroding Osage Fork (Gasconade River) valley located south and east of the figure 9 map area. At that time the deep east- and northeast-oriented Osage River valley north of the figure 9 map area did not exist and large volumes of south-oriented flood flow was moving along the present day Niangua River alignment. Headward erosion of the deep northeast-oriented Osage Fork valley from what were then newly eroded Gasconade and Missouri River valleys captured some of the flood flow moving south on the Niangua River alignment. The captured flood flow then moved in southeast, east, and northeast directions to reach the actively eroding Osage Fork (Gasconade River) valley head. Headward erosion of the deep Missouri-Osage River valley north of the figure 9 then beheaded the south-oriented flood flow route using the Niangua River alignment. Flood waters on the north end of the newly beheaded flood flow route reversed flow direction and began to erode the deep north-oriented Niangua River valley, which beheaded and reversed southeast-oriented flood flow routes which had been moving flood water to the newly eroded Osage Fork valley. Flood waters on the northwest ends of the beheaded southeast-oriented flood flow routes reversed flow direction to erode northwest-oriented Niangua River tributary valleys and to create the Niangua River-Osage Fork (Gasconade River) drainage divide.

Detailed map of Spring Hollow-Brush Creek drainage divide area

Figure 10: Detailed map of Spring Hollow-Brush Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.