• The purpose of this essay is to use topographic map interpretation methods to explore the Des Moines River-Missouri River drainage divide area landform origins in Clarke, Lucas, and Monroe Counties, Iowa, 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 Des Moines River-Missouri River drainage divide area landform evidence in Clarke, Lucas, and Monroe Counties, Iowa 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.

• Figure 1 illustrates a Des Moines River-Missouri River drainage divide area location map. The south-southwest and south-southeast oriented river flowing to the figure 1 southeast corner is the Mississippi River, which eventually flows to the Gulf of Mexico. The state west of the Mississippi River in the figure 1 north half is Iowa. South of Iowa is the state of Missouri. The south-southeast oriented river (with a southwest jog downstream from St. Joseph) in the figure 1 southwest quadrant is the Missouri River. South of the figure 1 southwest quadrant the Missouri River turns to flow in an east-northeast direction to Brunswick, Missouri (located just north of the figure 1 south center edge) and then turns to flow in a southeast and east direction to join the south-oriented Mississippi River. Note how Mississippi River tributaries from the west are predominately oriented in a southeast direction. The Des Moines River is a southeast oriented Mississippi River tributary flowing through Des Moines, Iowa to join the Mississippi River at the Iowa southeast corner. Note how west of Des Moines, Iowa there are several southeast oriented Des Moines River tributaries, with the southeast-oriented Middle River turning to flow in an east-northeast direction. South and east of Des Moines the Des Moines River has several northeast-oriented tributaries. South of the Des Moines River drainage basin in south central Iowa are headwaters of what become south-oriented Missouri River tributaries. Of particular interest to this essay are the east, east-southeast, and south oriented Chariton River (which flows to the Missouri River downstream from Brunswick, Missouri) and the south-southeast oriented Thompson River, which flows to the southeast- and south-oriented Grand River (which then flows to the Missouri River near Brunswick, Missouri). The Des Moines River-Missouri River drainage divide area in Clarke, Lucas, and Monroe Counties, Iowa is located east of the Thompson River and west of Rathbun Lake, which is the large reservoir located on the Chariton River in southern Iowa, and north of the Chariton River and is the drainage divide between north-oriented Des Moines River tributaries and south-oriented Missouri River tributaries.

• The Des Moines River-Missouri River drainage divide area in Clarke, Lucas, and Monroe Counties, Iowa was eroded by immense south oriented floods as deep valleys eroded headward into the figure 1 map region. The giant south oriented floods were derived from a rapidly melting thick North American ice sheet located north of the figure 1 map area (at least when the present day drainage network evolved). The ice sheet had been located in a deep “hole” created by deep glacial erosion and crustal warping caused by the ice sheet’s great weight. The figure 1 map area was located on the deep “hole’s” southern rim and was deeply eroded by melt water flood erosion prior to development of the drainage system seen today. How much material was stripped from the figure 1 map area by melt water flood erosion may never be determined, although it could measure in the hundreds of meters. Major rivers and their tributaries seen in the figure 1 map area evolved as deep valleys eroded headward into the region. The deep Mississippi River valley eroded headward from the Gulf of Mexico and deep east and southeast (and west and southwest) oriented valleys then eroded headward from the deep Mississippi River valley in sequence (from south to north) to capture the immense south-oriented melt water floods and to the divert the flood waters into the actively eroding Mississippi River valley. The Missouri River valley and the Des Moines River valley and their tributary valleys were just two of several such valley systems that eroded headward from the actively eroding Mississippi River valley. Headward erosion of the Missouri River valley occurred somewhat in advance of Des Moines River valley headward erosion. South and southeast oriented tributary valleys eroded headward from the actively eroding Missouri River valley along and across south- and southeast-oriented flood flow routes, and then were subsequently beheaded by headward erosion of the deep Des Moines River valley and its tributary valleys.

• Figure 2 provides a somewhat more detailed location map for the Des Moines River-Missouri River drainage divide area in Clarke, Lucas, and Monroe Counties, Iowa. County names and boundaries are shown. The Des Moines River flows in a southeast direction from Des Moines to the figure 2 east edge (east of Monroe County). Des Moines River tributaries of importance in this essay include Soap Creek, Cedar Creek, White Breast Creek, South River, and Middle River. Soap Creek originates in southeast Monroe County and flows in a southeast and east-northeast direction to join the Des Moines River east of the figure 2 map area. Cedar Creek originates near Russell in east central Lucas County and flows in an east and east-northeast direction almost to Albia in Monroe County before turning to flow in a northwest direction into the Marion County southwest corner. Once in Marion County Cedar Creek turns to flow in a northeast direction to join the Des Moines River. Northeast-oriented North Cedar Creek is a major Cedar Creek tributary. White Breast Creek originates near Osceola in Clarke County and flows in a generally east direction to Lucas in Lucas County before turning to flow in a north-northeast direction to join northwest-oriented Little White Breast Creek and then flowing in a northwest direction to Laconia in southeast Warren County. At Laconia White Breast Creek turns to flow in a northeast direction to the Des Moines River. The South River originates in the Clarke County northwest corner and flows in a northeast direction across the Madison County southeast corner and Warren County to join the Des Moines near the Warren County northeast corner. Squaw Creek and Otter Creek are northeast and north oriented South River tributaries also originating in northern Clarke County. The Middle River flows in a southeast direction to Webster (located on Madison County west border center) and then gradually changes to flow in a northeast direction through Bevington (located near center of Madison County east border) and then to join the Des Moines River near the Warren County northeast corner. The Thompson River flows in a south-southeast direction to the Union County southeast corner and then to figure 2 south edge. South of figure 2 the Thompson River flows to the southeast and south oriented Grand River, which flows to the Missouri River. Thompson River tributaries of significance in this essay include Fourmile Creek in eastern Union County and West and East Long Creek in southwest Clarke County. Chariton Creek originates near Weldon (located near center of Clarke County south border) and flows in an east-northeast and northeast direction to Chariton. Near Chariton the stream turns to flow in a northeast and then southeast direction and is renamed the Chariton River as it flows to the Lucas County southeast corner and then to the figure 2 south edge. South of the figure 2 map area the Chariton River turns to flow in a south direction to join the Missouri River (see figure 1). Few south-oriented Chariton River tributaries from the north are shown. Southeast-oriented streams located north and east of Chariton River in the figure 2 southeast corner flow to a northeast-oriented Des Moines River tributary east of the figure 2 map area. South and east of that unseen Des Moines River tributary are headwaters of several southeast-oriented Mississippi River tributaries.

• Figure 3 uses a reduced size topographic map to illustrate the South River-Thompson River drainage divide in northwest Clarke County and northeast Union County. The Thompson River flows in a south-southeast direction near the figure 3 west edge. Lorimor is the town located in the figure 3 northwest quadrant. Fourmile Creek originates near Lorimor and flows in a south-southeast direction and south direction to the figure 3 south edge (west half). Murray is the town just east of the figure 3 south center area. Sevenmile Creek is the south-southwest oriented stream between Fourmile Creek and Murray in the figure 3 south half. The south-oriented stream east of Murray is East Long Creek. South of the figure 3 map area Long Creek, Fourmile Creek, and Sevenmile Creek join the south-oriented Thompson River, which then flows to the southeast and south-oriented Grand River, which in turn flows to the Missouri River. The South River originates a short distance north and east of Lorimor and flows in a northeast and southeast direction before turning to flow in a northeast direction to the figure 3 north edge (just west of the northeast corner). North and east of the figure 3 map area the South River flows to the southeast-oriented Des Moines River. The northeast-oriented stream with a north and south oriented jog in the figure 3 east center area and flowing to the figure 3 east edge (just north of center) is Squaw Creek (South Squaw Creek is a Squaw Creek tributary located north and west of the highway intersection near the figure 3 southeast corner). The north and southeast oriented stream in the figure 3 southeast corner is White Breast Creek, which is also a Des Moines River tributary. Note how South River and Squaw Creek both have north-oriented tributaries. A close look at the drainage divide between the north-oriented South River tributaries and south-oriented Fourmile Creek tributaries in the region between Lorimor and Murray reveals a shallow through valley, which is defined by one 10-meter contour line on each side. While a subtle landscape feature the through valley provides evidence of a south-oriented flood flow channel which was beheaded and reversed by headward erosion of the deep northeast-oriented South River valley (which was probably eroded by reversed flood flow moving to what was then the newly eroded southeast-oriented Des Moines River valley). Close study of the figure 3 map area reveals still more through valleys. For example near the substation (Substa) north and east of Murray a shallow through valley links a north-oriented South River tributary valley with a southeast-oriented Squaw Creek tributary valley. The through valley provides evidence of a south-oriented flood flow channel and also evidence the deep Squaw Creek valley was eroded prior to headward erosion of the deep northeast-oriented South River valley. Study of more detailed topographic maps reveals still additional shallow through valleys eroded across the drainage divides. Figure 4 below provides a detailed topographic map of the Squaw Creek-East Long Creek drainage divide.

• Figure 4 provides a detailed topographic map of the Squaw Creek-East Long Creek drainage divide area east of Murray, which was seen in more detail in figure 3 above. Murray is the town straddling the south half of the figure 4 west edge. East Long Creek originates in section 12 and flows in a south direction through section 13 to the figure 4 south edge. Remember East Long Creek eventually flows to the Missouri River. Squaw Creek flows in a north-northeast direction from just north of Murray almost to the figure 4 north edge and then in an east direction to the figure 4 north center before turning to flow north of the figure 4 map area. Remember Squaw Creek eventually flows to the Des Moines River. Note the north-northeast and north oriented Squaw Creek tributary originating in the section 12 northeast corner and joining Squaw Creek just north of the section 6 center and how that tributary valley is linked by a shallow through valley with the south-oriented East Long Creek valley. The map contour interval is 20 feet and the through valley is defined by a single contour line on each side. However, valley orientations and the through valley provide evidence of a south-oriented flood flow route to the East Long Creek valley. Headward erosion of the deep Squaw Creek valley beheaded and reversed flood flow on the north end of that flood flow route to erode the north-oriented Squaw Creek tributary valley. Erosion of the deep north-oriented tributary valley was probably aided by the capture of flood flow from west of the actively eroding Squaw Creek valley head, which was eroding headward in a west direction. South Squaw Creek flows along the section 8 south edge and then in an east-northeast direction in section 9 before turning to flow in a southeast direction to the figure 4 east edge. White Beast Creek can be seen flowing in an east-southeast direction in sections 20 and 21 near the figure 4 south edge (east half). Remember White Breast Creek is also a Des Moines River tributary. Shallow through valleys can be seen linking the South Squaw Creek valley with the White Breast Creek valley, although relief along the drainage divide is very low. The figure 4 evidence suggests south-oriented flood flow moved across the entire figure 4 map area initially to the developing Thompson River valley system. Headward erosion the deep White Breast Creek valley then captured flood flow in the figure 4 southeast quadrant with South Squaw Creek valley headward erosion beheading and reversing flood flow to the White Breast Creek valley to erode the north-oriented South Squaw Creek tributary valleys. Next Squaw Creek valley headward erosion beheaded and reversed flood flow to the newly eroded South Squaw Creek valley and to what was still the actively eroding East Long Creek valley.

• Figure 5 uses a reduced size topographic map to illustrate the Squaw Creek-White Breast Creek drainage divide area north and east of Osceola, Iowa. Osceola is the large town located in the figure 5 southwest quadrant. Lucas is the somewhat smaller town located near the figure 5 east edge and directly east from Osceola. White Breast Creek flows in an east-southeast and northeast direction from near Osceola to the figure 5 east edge near Lucas. East of the figure 5 map area White Breast Creek eventually flows to the Des Moines River. Squaw Creek is the northeast and north oriented stream in the figure 5 northwest corner. South Squaw Creek is the north-northeast oriented Squaw Creek tributary near the figure 5 west edge. The northeast oriented stream with a southeast jog originating on the north edge of Osceola and flowing to the figure 5 north edge (just east of center) is North Otter Creek. Middle Otter Creek is a north-northeast oriented Otter Creek originating a short distance east of Osceola (Otter Creek is formed at the confluence of North and Middle Otter Creeks). Victory Creek is the north-oriented tributary joining Otter Creek at its elbow of capture in the figure 5 north center area (where Otter Creek turns from flowing in a southeast direction to flowing in a northeast direction). South Otter Creek originates a short distance east of the Middle Otter Creek headwaters and flows in an east-northeast direction before turning to flow in a north-northwest direction to the figure 5 north edge. North of the figure 5 map area South Otter Creek joins with Otter Creek and both Squaw Creek and Otter Creek flow in north directions to join the northeast-oriented South River, which flows to the southeast-oriented Des Moines River. The north-oriented Squaw Creek and Otter Creek valleys north of the figure 5 map area were eroded by reversals of flood flow on north ends of south-oriented flood flow routes beheaded by South River valley headward erosion. Flood flow routes were beheaded in sequence from east to west with the south-oriented flood flow on the Otter Creek alignment being beheaded and reversed first. The east-northeast oriented South Otter Creek valley segment eroded headward across the figure 5 map area to capture flood flow moving south from west of the actively eroding South River valley head. Next headward erosion of the northeast-oriented Otter Creek-Middle Otter Creek valley beheaded the south-oriented flood flow routes to the newly eroded South Otter Creek valley and diverted the flood flow more directly to the north-oriented Otter Creek valley. Headward erosion of the South River valley subsequently beheaded and reversed flood flow routes so as to erode north-oriented Squaw Creek valley segments while east- and northeast-oriented valley segments and tributary valleys eroded headward to capture south-oriented flood flow routes located west of the actively eroding South River valley head.

• Figure 6 uses a reduced size topographic map to illustrate the White Breast Creek-Chariton Creek drainage divide area located south of the figure 5 map area. Osceola is the town located near the figure 6 northwest corner and Lucas is the town located near the northeast corner. White Breast Creek flows in an east-southeast and northeast direction from near Osceola to the figure 6 northeast corner. North and east of figure 6 White Breast Creek flows to the southeast-oriented Des Moines River. South White Breast Creek flows in a northeast and east-northeast direction from the figure 6 west edge (south of center) to join White Breast Creek at its elbow of capture. North Hoosier Creek is the labeled southeast-oriented South White Breast Creek tributary and Hoosier Creek is the labeled east-oriented tributary. Weldon is the small town in the figure 6 southwest corner area. The east-northeast oriented stream between Weldon and South White Breast Creek is Chariton Creek, which as will be seen in figure 8 becomes the Chariton River, which eventually flows to the Missouri River. Note how the Chariton Creek valley is adjacent to and parallel with the deeper South White Breast Creek-White Breast Creek valley and remember the drainage divide between the two valleys is the divide between the Mississippi River drainage basin to the north and the Missouri River drainage basin to the south. Also note east-oriented Weldon Creek which originates just south of Weldon and then turns to flow in a south direction near the figure 6 south center edge. South of the figure 6 map area Weldon Creek becomes the south-oriented Weldon River, which eventually joins the Thompson River, which joins the Grand River, which flows to the Missouri River (west of where the Chariton River joins the Missouri River-see figure 1). Humeston is the small town located along the figure 6 south edge (in southeast quadrant). Note the north-oriented Chariton Creek tributary located between the south-oriented Weldon Creek drainage system and Humeston. This presence of adjacent drainage routes flowing in opposite directions is evidence the north-oriented Chariton Creek tributary valley was eroded by a reversal of south-oriented flood flow on the north end of a flood flow route beheaded by headward erosion of the east-oriented Chariton Creek valley. Unfortunately the contour interval for most of the figure 6 map area is 20 meters, which in low relief areas is too large to show shallow through valleys crossing drainage divides. Figure 7 below provides a more detailed map of the White Breast Creek-Chariton Creek drainage divide area near Smyrna (located near the figure 6 center).

• Figure 7 provides a detailed topographic map of the White Breast Creek-Chariton Creek drainage divide area near Smynra which was seen in less detail in figure 6 above. Smynra is located in the northwest corner of section 22, which is located in the figure 7 southeast quadrant. White Breast Creek flows in an east direction along the figure 7 north edge and joins east and northeast oriented South White Breast Creek in section 3 in the figure 7 northeast quadrant. Chariton Creek flows in an east-northeast direction from the figure 7 south center edge to the figure 7 east edge (in section 23 in the southeast quadrant). Note north-oriented White Breast Creek and South White Breast Creek tributaries from the south and south-oriented South White Breast Creek and Chariton Creek tributaries from the north. Follow the White Breast Creek-South White Breast Creek drainage divide westward from section 4 and note shallow through valleys eroded across that drainage divide. For example near the section 4 south center border a shallow through valley is defined by two 10-foot contour lines on the east and three contour lines on the west. In the section 6 south half a south-southeast oriented South White Breast Creek tributary valley is linked by two different shallow through valleys with two north-oriented White Breast Creek tributary valleys. The eastern section 6 through valley is defined by at least four contour lines on each side while the western through valley is defined by at least three contour lines on each side. In the section 1 southeast quadrant another shallow through valley links a south-oriented South White Breast Creek tributary valley with a north-oriented White Breast Creek tributary valley. Additional shallower and more subtle through valleys are also present. The shallow through valleys provide evidence of multiple south-oriented flood flow channels prior to headward erosion of the deep east-oriented White Breast Creek valley. Flood waters at the time the shallow through valleys were eroded were flowing to what was then the newly eroded and deep South White Breast Creek valley and were flowing on a surface at least as high as the present day White Breast Creek-South White Breast Creek drainage divide. Headward erosion of the deep east-oriented White Breast Creek valley beheaded the south-oriented flood flow channels in sequence from east to west. Flood waters on north ends of beheaded flood flow channels reversed flow direction to erode the north-oriented White Breast Creek tributary valleys. Shallow through valleys can also be found along the South White Breast Creek-Chariton Creek drainage divide (which is today the Des Moines River-Missouri River drainage divide) and provide evidence that prior to headward erosion of the east-oriented South White Breast Creek valley flood waters flowed to what was then the newly eroded Chariton Creek valley.

• Figure 8 uses a reduced size topographic map to illustrate the Little White Breast Creek-Chariton River drainage divide area east of the figure 6 map area and includes overlap areas with figure 6. Chariton is the town located near the figure 8 south center. Lucas is the town near the highway intersection west of Chariton. White Breast Creek flows in an east direction from the figure 8 west edge to Lucas before turning to flow in a north-northeast direction to the figure 8 north center edge. South Otter Creek is the northeast and north-northwest oriented stream flowing to the figure 8 northwest corner. Note how both White Breast Creek and South Otter Creek have northwest and north oriented tributaries from the south and east and some south and southeast oriented tributaries from the north and west. East-oriented Chariton Creek can be seen meandering along and across the figure 8 south edge (near southwest corner) and then turns to flow in a north-northeast direction to the Chariton city southwest corner before flowing in a south-southeast direction to the figure 8 south edge. Russell is the small town located near the figure 8 southeast corner. Between Chariton and Russell are headwaters of north-northeast oriented Little White Breast Creek, which joins White Breast Creek just north of the figure 8 map area. North of the figure 8 map area White Breast Creek flows in a northwest and then northeast direction to join the southeast-oriented Des Moines River. Williamson is the small town located on the railroad line in the figure 8 northeast quadrant. The north-oriented stream flowing to the figure 8 north edge, north of Williamson, is English Creek, which north of the figure 8 map area turns to flow in a northeast direction to join the Des Moines River. The northeast-oriented stream flowing to the figure 8 east edge (north half) and followed by the old railroad grade is North Cedar Creek, which flows to northeast-oriented Cedar Creek, which in turn flows to the Des Moines River. Note how North Cedar Creek has northwest-oriented headwaters and tributaries from the south and east and southeast-oriented tributaries from the north and west. The north-northeast and south-southeast oriented Chariton River loop probably originated when headward erosion of the east-southeast oriented Chariton River valley beheaded a northwest-oriented tributary to what was then an east, north-northeast, and north oriented tributary (on the present day Chariton Creek alignment) to what was then the newly eroded White Breast Creek valley. Reversal of flood flow on the southeast end of the beheaded northwest-oriented tributary (which had previously been reversed by White Breast Creek valley headward erosion) eroded the south-southeast oriented Chariton River valley segment and also captured flood flow from the east-and north-northeast oriented Chariton Creek valley. Prior to being captured the east- and north-northeast oriented Chariton Creek valley had eroded headward from the actively eroding White Breast Creek valley to capture south-oriented flood flow, which had been flowing to actively eroding south-oriented Missouri River tributary valleys. This figure 8 evidence suggests headward erosion of Des Moines River and Missouri River tributary valleys reached the figure 8 map area at approximately the same time and were actively capturing flood flow routes from each other.

• Figure 9 uses a reduced size topographic map to illustrate the Cedar Creek-Chariton River drainage divide area located east of the figure 7 map area (there is no overlap with figure 7). Rathbun Lake is located along the figure 9 south edge area and is a reservoir flooding the east-southeast oriented Chariton River valley and several of its southeast-oriented tributary valleys. Moravia is the town located near the figure 9 southeast corner. The southeast-oriented stream originating just south of Moravia is the headwaters of southeast and east-northeast oriented South Soap Creek, which flows Soap Creek. Soap Creek originates in the figure 9 east center area and flows to the east edge (south half). East of the figure 9 map area Soap Creek turns to flow in an east-northeast direction to the southeast-oriented Des Moines River. Albia is the larger town located near the figure 9 northeast corner and Melrose is a much smaller town located in the figure 9 west center area. The stream flowing in an east direction through Melrose and then turning to flow in a northeast and north direction to the figure 9 north edge (west of Albia) is Cedar Creek. North of the figure 9 map area Cedar Creek turns to flow in a northwest and then northeast direction to join the southeast-oriented Des Moines River. Note how Cedar Creek has southeast-oriented tributaries from the north and west and northwest-oriented tributaries from the south and east. Note further how some of the major northwest-oriented Cedar Creek tributaries are linked to southeast-oriented Chariton River tributaries and also to southeast-oriented Soap Creek tributaries. Coal Creek is the northwest-oriented tributary joining Cedar Creek just west of Albia and flows on the same alignment as the Soap Creek southeast-oriented headwaters. Inghram Branch is the northwest-oriented Cedar Creek tributary originating near Melrose and is on the same alignment as the southeast-oriented South Soap Creek headwaters. Mormon Branch is a northwest-oriented tributary joining Cedar Creek near the figure 9 center and is linked to southeast-oriented Buck Branch, which is a Chariton River tributary. A shallow northwest-southeast oriented through valley can be seen linking the Mormon Branch and Buck Branch valleys. The northwest-southeast alignment of these linked tributary valleys provides evidence headward erosion of the Cedar Creek valley beheaded multiple southeast-oriented flood flow channels and flood waters on northwest ends of the beheaded flood flow channels reversed flow direction to erode the northwest-oriented Cedar Creek tributary valleys. The evidence also suggests these southeast-oriented flood flow channels were being captured by headward erosion of deep south-oriented Chariton River valley, which had eroded headward from the newly eroded Missouri River valley in the south and by northeast and east-northeast oriented tributaries eroding headward from the actively eroding Des Moines River valley to the east and north.

• Figure 10 provides a detailed topographic map of the Mormon Branch-Buck Branch drainage divide area seen in less detail in the figure 9 map area above. Buck Branch is a south-southeast oriented stream in sections 2 and 11 in the figure 10 southeast quadrant and drains to the Chariton River. The Buck Branch valley is flooded by Rathbun Reservoir, which floods the Chariton River and tributary valleys and which can be seen in its entirety on figures 1 and 2. The north-northwest oriented stream originating in section 35 and located on the same alignment as Buck Branch is Mormon Branch, which drains to northeast-oriented Cedar Creek. Remember, Cedar Creek flows to the Des Moines River while the Chariton River flows to the Missouri River. Note the shallow through valley linking the north-northwest-oriented Mormon Branch valley with the south-southeast oriented Buck Branch valley. The valley in the section 35 and 2 area is defined by a single 10-foot contour line, however elevations rise higher both to the east and west. Note high elevations near the figure 10 east center edge and also near the figure 10 west center edge. While not significantly higher, those elevations above 1000 feet provide evidence of a broad and shallow southeast-oriented flood flow channel, which stripped ten of more feet of bedrock material from most of the figure 10 map area between the time of headward erosion of the deep southeast-oriented Chariton River valley and the time of headward erosion of the deep northeast-oriented Cedar Creek valley. The southeast-oriented Chariton River tributary valleys eroded headward along southeast-oriented flood flow routes prior to beheading and reversals of those flood flow routes by Cedar Creek valley headward erosion. The figure 10 evidence is more complicated than the simplified explanation I have given so far. The east-northeast oriented stream in the figure 10 map area is the Moffat Branch, which flows to the north-northwest oriented Mormon Branch (see figure 9). Headward erosion of the deep Moffat Branch valley beheaded and reversed southeast-oriented flood flow routes to southeast-oriented Honey Creek (a Chariton River tributary located in the figure 10 southwest corner area) prior to beheading and reversing of southeast-oriented flood flow routes by the actively eroding Cedar Creek valley.

Additional information and sources of maps studied