Abstract:

The Little Sac River-Pomme de Terre River drainage divide area in Polk, Dallas, Greene, and Webster Counties, Missouri is the drainage divide between two north-oriented Osage River tributaries and evolved during a massive reversal of an immense south-oriented flood. South-oriented flood waters were derived from a rapidly melting North American ice sheet and flowed south across the Polk, Dallas, Greene, and Webster County area to what were then actively eroding tributaries which had eroded headward from what was then the newly eroded southeast-oriented White River valley. Headward erosion of the deep east-oriented Missouri River-Osage River valley north of the Polk, Dallas, Greene, and Webster County region beheaded the south-oriented flood flow routes to the Polk, Dallas, Greene, and Webster County area in sequence from east to west. Flood waters on north ends of newly beheaded flood flow routes reversed flow direction to erode deep north-oriented valleys. The rapidly eroding deep north-oriented valleys captured flood flow still moving south to the west of the actively eroding Osage River valley head. The captured flood flow moved in southeast, east, and northeast directions to the new and rapidly eroding north-oriented valleys. Headward erosion of the deep Osage River valley then beheaded and reversed these south, southeast, east, northeast, and north oriented flood flow routes to produce the present day Pomme de Terre River and Little Sac River-Sac River valleys and their tributary valleys. Evidence supporting this flood origin interpretation includes orientations and positions of present day valleys and through valleys eroded across present day drainage divides.

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 Little Sac River-Pomme de Terre River drainage divide area landform origins in Polk, Dallas, Greene, 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 Little Sac River-Pomme de Terre River drainage divide area in Polk, Dallas, Greene, 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 paradigm related essay).

Little Sac River-Pomme de Terre River drainage divide area location map

Figure 1: Little Sac River-Pomme de Terre 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 Little Sac River-Pomme de Terre River drainage divide area in Polk, Dallas, Greene, and Webster Counties, Missouri and illustrates a region in southwest Missouri. Springfield is the largest southwest Missouri city and the Little Sac River-Pomme de Terre River drainage divide is located directly north from Springfield. The Little Sac River flows in a north-northwest direction from the Springfield area to join the north-oriented Sac River near Stockton and the Sac River then flows in a north direction to join the Osage River near Osceola. The Pomme de Terre River originates east of Springfield and flows in a north-northwest and north direction to join the east-oriented Osage River at the Harry S Truman Reservoir. The Osage River is formed by several tributaries near Schell City and flows in an east and northeast direction to Harry S. Truman Reservoir and then in an east direction to Lake of the Ozarks (another large reservoir flooding the Osage River valley). Downstream from Lake of the Ozarks the Osage River flows in a northeast direction to the figure 1 north edge. North and east of the figure 1 map area the Osage River joins the Missouri River, which then flows in an east direction to join the south-oriented Mississippi River. South of Springfield is the southwest and south-southwest oriented James River, which south of the figure 1 map area flows in a south direction to join the southeast-oriented White River, which eventually flows to the south-oriented Mississippi River. The drainage divide between the north-oriented Little Sac and Pomme de Terre Rivers and the south-oriented James River is also the divide between the Missouri River drainage basin to the north and the White River drainage basin to the south. The Osage River-Weaubleau Creek drainage divide area in St Clair, Benton, and Hickory Counties essay described the region located north of the Little Sac River and the Little Sac River-James River drainage divide area in Dade, Polk, and Greene Counties essay described the region located west of the Little Sac River-Pomme de Terre River drainage divide area.Essays can be found under Osage River on the sidebar category list.  Evidence presented in hundreds of Missouri River drainage basin landform origins research project essays describes immense south-oriented floods from a rapidly melting North America ice sheet, which flowed across the figure 1 map area to what were at that time south-oriented tributary valleys which were actively eroding headward from what was then the newly eroded White River valley. Headward erosion of the deep east-oriented Missouri River-Osage River valley beheaded the south-oriented flood flow routes in sequence from east to west. Flood waters on north ends of newly beheaded flood flow routes reversed flow direction to erode deep north-oriented valleys. The deep north-oriented valleys captured flood flow still moving south on flood flow routes west of the actively eroding Osage River valley head. Captured flood water moved in a southeast, east, and northeast directions to reach the actively eroding north-oriented Osage River tributary valleys.

Little Sac River-Pomme de Terre River drainage divide area detailed  location map

Figure 2: Little Sac River-Pomme de Terre River drainage divide area detailed  location map. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 2 provides a more detailed location map for the Little Sac River-Pomme de Terre River drainage divide area in Polk, Dallas, Greene, and Webster Counties. County names and boundaries are shown as are relevant regions in Polk, Dallas, Greene, and Webster Counties. The Little Sac River originates neat Strafford in eastern Greene County and flows in a west, north-northwest, and northwest direction to join the north-oriented Sac River near the figure 2 northwest corner. The North Dry Sac River is a major northwest-oriented tributary originating in northeast Greene County and joining the Little Sac River in southern Polk County. North of the figure 2 map area the Sac River continues to flow in a north direction until it joins the east oriented Osage River. The Pomme de Terre River originates as a south-oriented stream in western Webster County and then turns to flow in a northwest direction across the Greene County northeast corner and Dallas County southwest corner before flowing in a north-northwest direction in Polk County. North of the figure 2 map area the Pomme de Terre River flows in a north direction to the east and northeast-oriented Osage River, which then flows to the east-oriented Missouri River, which in turn flows to the south-oriented Mississippi River. The James River originates near Marshfield in Webster County and flows in a southwest direction to the figure 2 south edge south of Springfield. South of the figure 2 map area the James River flows in a south direction to the southeast-oriented White River, which eventually flows to the Mississippi River. Almost all figure 2 drainage routes north of the James River are north-oriented Osage River tributaries and the valleys were eroded during a massive reversal of flood flow that had been moving south to what were at that time actively eroding south-oriented tributary valleys which had eroded headward from what was then the newly eroded White River valley. Headward erosion of the deep east-oriented Missouri River-Osage River valley north of the figure 2 map area then beheaded the south-oriented flood flow routes in sequence from east to west. Flood waters on north ends of beheaded flood flow routes reversed flow direction to erode deep north-oriented valleys. As these north-oriented valleys were being eroded flood waters west of the actively eroding Osage River valley head continued to flow south and were captured by the actively eroding north-oriented valleys located east of he Osage River valley head. The captured flood flow often moved in a southeast, east and then northeast direction to the actively eroding north-oriented valleys. These southeast, east, and northeast oriented flood flow routes were subsequently beheaded by deep north-oriented valleys as the deep Osage River valley eroded further west. Flood waters on northwest ends of the beheaded southeast, east, and northeast oriented flood flow routes reversed flow direction to erode southwest, west, and northwest oriented valleys.

Little Sac River-Pomme de Terre River drainage divide area in Polk County

Figure 3: Little Sac River-Pomme de Terre River drainage divide area in Polk County. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 illustrates the Little Sac River-Pomme de Terre River drainage divide area in Polk County. Bolivar is the large town near the figure 3 north edge. Aldrich is the small town located near the figure 3 west edge (south half). Morrisville Station is the much smaller town near the figure 3 south center edge and Wishart is the small town just west of Morrisville Station. The Little Sac River flows in a northwest direction in the figure 3 southwest area. Slagle Creek is the west-southwest and west oriented Little Sac River tributary flowing between Morrisville Station and Wishart and the figure 3 south edge. Note how Slagle Creek has southwest oriented headwaters. Tommie Creek is the southeast and south-southwest oriented tributary joining Slagle Creek near Morrisville Station. Bear Creek is the northwest, west, and northwest oriented stream flowing to the figure 3 west edge (north half). The Pomme de Terre River is the north-northwest oriented river located near the figure 3 east edge. McKinney Branch is the northeast-oriented tributary joining the Pomme de Terre River near the figure 3 east center edge. Kilburn Branch is the northeast-oriented tributary located directly south of McKinney Branch. Note how the southwest oriented Slagle Creek headwaters are aligned with northeast-oriented McKinney Branch. Figure 4 below provides a more detailed map of the Slagle Creek-McKinney Branch drainage divide area which was eroded by flood water that had moved south on what is today the north-oriented Sac River alignment and which had been captured by north-oriented flood water eroding the deep north-oriented Pomme de Terre River valley. How was this possible? Initially an immense south-oriented flood flowed across the entire figure 3 map area on a topographic surface at least as high as the highest figure 3 elevations today. Headward erosion of the deep east-oriented Osage River valley north of the figure 3 map area then beheaded south-oriented flow routes moving across the figure 3 east margin. Flood waters on the north end of a beheaded flood flow route reversed flow direction and began to erode the deep north-oriented Pomme de Terre River valley. The actively eroding north-oriented Pomme de Terre River valley then began to capture flood flow moving south along flood flow routes west of the actively eroding Osage River valley head (which probably was located at that time north of the figure 3 map area). The captured flood flow flood moved south on what is now the north-oriented Sac River valley alignment, southeast on the present day northwest-oriented Little Sac River valley alignment, east and northeast on the modern-day southwest and west-oriented Slagle Creek alignment, and finally northeast along the McKinney Branch alignment. Headward erosion of the deep Osage River valley next beheaded that flood flow route and flood waters on the north end of the beheaded flood flow route reversed flow direction to erode the north-oriented Sac River valley system, which includes the northwest-oriented Little Sac River valley and southwest and west-oriented Slagle Creek valley.

Detailed map of Slagle Creek-McKinney Branch drainage divide area

Figure 4: Detailed map of Slagle Creek-McKinney Branch drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 provides a detailed map of the Slagle Creek-McKinney Branch drainage divide area seen in less detail in figure 3 above. Slagle is the small community located south of the figure 4 center area and Cedar Vista is the small community located south of Slagle. Karlin is a place-name in the figure 4 northwest corner area. Slagle Creek flows in a southwest direction just south of Cedar Vista from section 4 to the figure 4 south edge. Tommie Creek is the southeast and south-southwest oriented Slagle Creek tributary flowing from the figure 4 west center area to the southwest corner area and joins Slagle Creek south of the figure 4 southwest corner. West and south of the figure 4 map area Slagle Creek joins the northwest-oriented Little Sac River which flows to the north-oriented Sac River. McKinney Branch is the northeast-oriented stream flowing to the figure 4 northeast corner. North and east of the figure 4 map area McKinney Branch and other north-northeast oriented drainage routes in the figure 4 east half flow to the north-oriented Pomme de Terre River. Note the hill near Karlin which rises to at least 1220 feet (the map contour interval is ten feet). Also note elevations of hills in the figure 4 southeast corner area which rise to more than 1250 feet in elevation. Then note elevations in the Slagle Creek-McKinney Branch drainage divide area between the northwest and southeast corner areas. A through valley located near the corner of sections 33, 34, 4, and 5 links a southwest oriented Slagle Creek tributary valley with the northeast-oriented McKinney Branch valley and has an elevation of between 1110 and 1120 feet. Other shallow southwest-northeast oriented through valleys are also eroded into the drainage divide area. However the entire drainage divide area has been eroded deeper than the elevations of the hills in the figure 4 northwest and southeast corners. Depending on which hill one uses 100 or more feet of material has been eroded from the drainage divide area. The erosion was done by flood water moving south on the present day north-oriented Sac River valley alignment west of the figure 4 map and which was captured by reversed flood flow eroding the north-oriented Pomme de Terre River valley east of the figure 4 map area. The captured flood water moved east on the Slagle Creek alignment to reach the figure 4 map area and then moved in a northeast direction to the actively eroding north-oriented Pomme de Terre River valley. The south, southeast, east, northeast and north oriented flood flow route was beheaded and reversed by headward erosion of the deep Osage River to erode the southwest- and west-oriented Slage Creek valley and the northwest-oriented Little Sac River valley, which suggests volumes of flood water involved were immense.

North Dry Sac River-Pomme de Terre River drainage divide area

Figure 5: North Dry Sac River-Pomme de Terre River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the North Dry Sac River-Pomme de Terre River drainage divide area located south and east of the figure 3 map area and includes overlap areas with figure 3. Slagle and Cedar Vista are the two small towns located just west of the figure 5 north center edge area. Morrisville Station and Wishart are located in the figure 5 northwest quadrant and Morrisville is the small town located south of Morrisville Station. Brighton is a place-name located south of the figure 5 center and Pleasant Hope is a place-name near the figure 5 east center area. The Little Sac River is located in the figure 5 southwest quadrant and flows in a north direction from the figure 5 south edge (west half) before turning to flow in west-northwest direction to the figure 5 west center edge. North Dry Sac River flows in a west-northwest direction from the figure 5 south edge (east half) to join the west-northwest oriented Little Sac River. Slagle Creek flows in a west-southwest and west direction in the figure 5 northwest quadrant to the figure 5 west edge (north half) and west of the figure 5 map area joins northwest-oriented Little Sac River. Bear Creek is a southwest and west oriented tributary joining the North Dry Sac River south of Brighton. The Pomme de Terre River flows in a northwest direction from the figure 5 east edge (south half) and after a jog to the north and then west it turns to flow in a north-northwest direction to the figure 5 north edge (east half). The northwest-oriented Pomme de Terre River valley probably was initiated by captured south oriented flood flow moving in the present day north-oriented Pomme de Terre River drainage basin which was moving in a southeast and east direction to an actively eroding north-oriented valley in the north-oriented Niangua River drainage basin located east of the figure 5 map area and flow was reversed when Osage River valley headward erosion beheaded and reversed flood flow on the route. Note northwest-oriented Sycamore Creek flowing from the figure 5 center area to the Pomme de Terre River. Also note how the Sycamore Creek valley is linked by a through valley with a west and northwest oriented Slagle Creek tributary valley. Similar through valleys link the southwest and west oriented Bear Creek valley with the valley of a north-oriented Pomme de Terre River tributary near Pleasant Hope. These through valley valleys provide evidence of flood flow routes used by captured flood waters moving south in the present day north-oriented Sac River drainage basin and then flowing in southeast and east directions before turning to flow northeast and north to what was then the actively eroding north-oriented Pomme de Terre River valley. Headward erosion of the deep Osage River valley then beheaded the south, southeast, east, and northeast oriented flood flow routes and triggered a flood flow reversal that eroded the present day Sac River valley system.

Detailed map of Slagle Creek-Sycamore Creek drainage divide area

Figure 6 provides a detailed map of the Slagle Creek-Sycamore Creek drainage divide area seen in less detail in figure 5 above. Slagle Creek flows in a west-southwest direction in the figure 6 northwest corner and west of the figure 6 map area flows to the northwest oriented Little Sac River. Note the northwest oriented Slagle Creek tributary originating in the section 28 area and flowing through section 20. The northwest-oriented valley in which that tributary flows is linked by a well-defined and narrow through valley in section 22 with the northwest- and north-oriented Sycamore Creek valley. North of the figure 6 map area Sycamore Creek joins the north-oriented Pomme de Terre River. Numerous similar through valleys can be seen crossing the north-south oriented drainage divide between the north-oriented Sac River to the west and the north-oriented Pomme de Terre River to the east. The through valleys provide evidence of multiple east-oriented flood flow routes used by flood waters which had been moving south in what is now the north-oriented Sac River drainage, which were captured by headward erosion of the deep north-oriented Pomme de Terre River valley. Headward erosion of the deep east-oriented Osage River valley north of the figure 6 map area beheaded south-oriented flood flow on the Pomme River alignment before it beheaded south-oriented flood flow on the Sac River alignment. Reversed flood flow on the newly beheaded Pomme de Terre River alignment began to erode the north-oriented Pomme de Terre River valley while flood water was still moving south in the present day north-oriented Sac River drainage basin. The deep north-oriented and rapidly eroding Pomme de Terre River valley captured south-oriented flood flow from the Sac River drainage basin area and the captured flood flow moved in southeast, east, and northeast directions to reach the actively eroding and north-oriented Pomme de Terre River valley. Headward erosion of the deep Osage River valley north of the figure 6 map area then beheaded south-oriented flood flow routes in the Sac River drainage basin and flood waters on north ends of those flood flow routes reversed flow direction to erode the north-oriented Sac River and tributary valleys and to capture south-oriented flood flow from flood flow routes still further to the west. The flood flow reversal eroded the west-oriented Slagle Creek valley and tributary valleys.

Little Sac River-Little Pomme de Terre River drainage divide area

Figure 7: Little Sac River-Little Pomme de Terre River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Little Sac River-Pomme de Terre River drainage divide area located south and east of the figure 5 map area. Glidewell is the place-name in the figure 7 southwest corner. The Little Sac River flows in a west-northwest direction to and through Fellows Lake (a reservoir flooding the Little Sac River valley) and then turns to flow in a southwest direction to the near Glidewell. West of the figure 7 map area the Little Sac River turns to flow in a northwest, north. and northwest direction to join the north-oriented Sac River. The North Dry Sac River flows in a northwest, west, and northwest direction in the figure 7 northwest quadrant. Simms Branch is the northwest-oriented tributary located south of the west-oriented North Dry Sac River segment. King Branch is the north and north-northwest oriented tributary joining the North Dry Sac River near the figure 7 west edge (near northwest corner). The Pomme de Terre River flows from the figure 7 east edge (just south of the east center edge) in a northwest direction to the figure 7 north edge. The South Fork Pomme de Terre River flows from the figure 7 southeast corner area in a north direction to join the Pomme de Terre River near the figure 7 east edge. West of the Pomme de Terre River is the northwest, north-northwest, and northwest oriented Little Pomme de Terre River which originates in the figure 7 east center area and which flows to the figure 7 north center edge. The northwest orientation of many figure 7 valleys probably relates to southeast movement of flood waters from west of the actively eroding Osage River valley head to north-oriented valleys east of the figure 7 map area. These north-oriented valleys include the north-oriented Niangua River and Gasconade River valleys both of which are located a short distance east of the figure 7 map area. Headward erosion of the deep Missouri River-Osage River valley north of the figure 7 map area would have permitted the north-oriented Gasconade and Niangua River valleys to erode south so as to reach the region east of figure 7 at about the same the actively eroding Missouri River-Osage River valley would have been beginning to behead south-oriented flood flow in what is now the north-oriented Pomme de Terre River drainage basin. A close look at the figure 7 map area reveals shallow through valleys linking the Little Sac River drainage basin with the Pomme de Terre River drainage basin, although the through valleys are better seen on more detailed maps. Figure 8 below provides a detailed map of the Little Sac River-South Fork Pomme de Terre River drainage divide area to better illustrate shallow through valleys crossing that drainage divide.

Detailed map of Little Sac River- South Fork Pomme de Terre River drainage divide area

Figure 8: Detailed map of Little Sac River- South Fork Pomme de Terre River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 provides a detailed map of the Little Sac River-South Fork Pomme de Terre River drainage divide area seen in less detail in the figure 7 southeast quadrant. The South Fork Pomme de Terre River is the north-oriented stream near the figure 8 east edge and flowing from the figure 8 south edge to the north edge. The north-northwest oriented Pomme de Terre River crosses the figure 8 northeast corner and north of the figure 8 map area is joined by the north-oriented South Fork. Northwest-oriented Spring Creek in the figure 8 northwest quadrant is a tributary to the northwest and north-oriented Little Pomme de Terre River which originates in section 15 near the figure 8 center and which joins the Pomme de River north of the figure 8 map area. The northwest-oriented stream in section 27 and turning to flow in a west-northwest and west direction in sections 22, 21, and 20 is the Little Sac River. Note how the Little Sac River valley in section 26 is linked by what appears to be a shallow through valley with the north-oriented South Fork Pomme de Terre River valley. The through valley floor is in the 1430-1440 foot range. A hill-top in section 22 to the north is higher than 1490 feet and a hill-top in section 15 is marked as having an elevation of 1518 feet. Just south of the figure 8 map area elevations rise to over 1500 feet at the town of Strafford in the section south of section 27 (see figure 9 below). Again this through valley is deeper and broader than it first appears and is a water eroded feature eroded by east-oriented flood flow captured from flood waters still moving south in the Sac River drainage basin and moving to what was then the actively eroding north-oriented Pomme de Terre River valley, where flood flow had been reversed to move to the newly eroded and deep east-oriented Osage River valley. Study of the figure 8 map area reveals other through valleys suggesting a somewhat more complex pattern of flood flow movements than I have described, however I believe the complexities fit within the general pattern described.

Pomme de Terre River-James River drainage divide area

Figure 9 illustrates the Pomme de Terre River-James River drainage divide area located east and slightly south of the figure 7 map area and includes overlap areas with figure 7. Marshfield is the larger town located in the figure 9 northeast quadrant. Strafford is the town located near the west edge in the figure 9 southwest quadrant. The James River flows in a west-northwest direction from the figure 9 southeast corner to the south center area and then turns to flow in a south-southwest direction to the figure 9 south edge. South of figure 9 the James River after flowing in a southwest direction turns to flow south to the southeast-oriented White River, which then eventually reaches the south-oriented Mississippi River. Note southwest-oriented James River tributaries south of Marshfield. Turnbo Creek for example originates south of Marshfield and flows in a southwest direction to join the James River in the figure 9 south center area. Northeast-oriented Hannah Branch in the figure 9 east center edge area flows to the northeast oriented Osage Fork Gasconade River, which flows to the northeast and north-oriented Gasconade River, which joins the east oriented Missouri River east of where the Osage River joins the Missouri River. North-oriented streams flowing to the figure 9 northeast quadrant north edge are tributaries to the north-oriented Niangua River, which flows to the east and northeast-oriented Osage River located north of the figure 9 map area. The Pomme de Terre River originates a short distance west of Marshfield and flows in a southwest direction to the figure 9 center and then turns to flow in a northwest direction to the figure 9 northwest corner. North and west of the figure 9 map area as previously seen the Pomme de Terre River flows in a north direction to the Osage River. As seen in figure 7 and 8 above just north of Strafford near the figure 9 west edge are headwaters of the west-northwest, southwest, northwest, north, and northwest oriented Little Sac River, which flows to the north-oriented Sac River, which flows to the Sac River. Figure 9 drainage history began with south-oriented flood flow moving across the entire figure 9 map area to what was then the actively eroding White River valley south of the figure 9 map area. Headward erosion of the deep northeast-oriented Gasconade River and Osage Fork Gasconade River valley from what was then the actively eroding Missouri River valley next began to capture flood flow moving south in the present day Niangua River, Pomme de Terre River and Sac ,River drainage basins. The captured flood waters moved in a southeast and then northeast direction to the actively Osage Fork Gasconade River valley. Headward erosion of the deep south-oriented James River valley beheaded some of the southeast-northeast oriented flood flow routes and flood waters on east ends of those flow routes reversed flow direction to erode southwest-oriented James River and tributary valley segments. Headward erosion of the Missouri River-Osage River then beheaded south-oriented flood flow routes in the Niangua, Pomme de Terre, and Sac River drainage basins in sequence from east to west. Flood waters on north ends of beheaded flood flow routes reversed flow direction to erode north-oriented valleys. Northwest-oriented valleys seen in figure 9 were eroded by reversals of flood flow along southeast-oriented flood flow routes to the earlier eroded north-oriented valleys.

Detailed map of Pomme de Terre River-James River drainage divide area

Figure 10: Detailed map of Pomme de Terre River-James River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 provides a detailed map of the Pomme de Terre River-James River drainage divide area seen in less detail in the figure 9 center area. The Pomme de Terre River flows in a southwest direction from the figure 10 north edge (east half) to the figure 10 north center and then turns to flow in a northwest direction to the figure 10 north edge (west half). North and west of the figure 10 map area the Pomme de Terre River flows in a north direction to join the east and northeast oriented Osage River, which flows to the east-oriented Missouri River. Turnbo Creek flows in a southwest direction from the figure 10 west edge to the figure 10 south center edge. South of the figure 10 map area Turnbo Creek joins the southwest oriented James River which turns to flow south to the southeast oriented White River. The Pomme de Terre River-Turnbo Creek drainage divide seen in figure 10 is the drainage divide between the Missouri River drainage basin to the north and the White River drainage basin to the south. Note the north-south oriented through valley located east of Northview in the figure 10 south center area. The through valley floor appears to have an elevation of between 1410 and 1420 feet. Further east along the drainage divide elevations rise to more than 1500 feet. Elevations greater than 1500 feet are also found along the drainage divide just west of the figure 10 map area. Between the two areas of 1500 foot or higher elevations the drainage divide is lower providing evidence of a south-oriented flood flow route which was captured when headward erosion of the deep Osage River valley north and west of the figure 10 map area beheaded and reversed south-oriented flood flow in the present day Pomme de Terre River drainage basin. By recognizing the 1500 foot plus elevations on either an observer can see the through valley is broader and deeper than it first appears. During the resulting flood flow reversal the deep northwest-oriented Pomme de Terre River valley eroded headward into the figure 10 map to capture southwest-oriented flood flow that had been moving to the southwest- and south-oriented James River valley. Probably the southwest-oriented Pomme de Terre River and James River-Turnbo Creek alignments were initially established by captured flood waters moving in a northeast direction to what were then actively eroding northeast-oriented Osage Fork Gasconade River tributary valleys east of the figure 10 map area. Headward erosion of the deep south-oriented James River valley south and west of the figure 10 map area beheaded and reversed the James River-Turnbo Creek alignment flood flow while as already described headward erosion of the deep Pomme de Terre River valley beheaded and reversed the southwest-oriented Pomme de Terre River alignment flow.

Additional information and sources of maps

This essay has only provided a sample of the drainage divide evidence supporting the “thick ice sheet that melted fast” geomorphology paradigm. Many additional examples could be provided, especially by using more detailed topographic maps. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of supporting data. Maps used in this study were created by the United Survey and can be purchased in hard copy from the United States Geological Survey or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories located in major research libraries and elsewhere throughout the United States and in other countries. Illustrations used in this essay were created using National Geographic Society TOPO software and digital data. National Geographic Society digital maps can be purchased from the National Geographic Society or from dealers offering National Geographic Society digital maps.