• The purpose of this essay is to use topographic map interpretation methods to explore the Des Moines River-Nishnabotna River drainage divide area landform origins in Audubon and Guthrie 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-Nishnabotna River drainage divide area landform evidence in Audubon and Guthrie 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 provides a location map for the Des Moines River-Nishnabotna River drainage divide area in Audubon and Guthrie Counties, Iowa. Iowa is the labeled state occupying most of the figure 1 map area with Missouri being south of Iowa along the figure 1 south edge. The Missouri River flows in a south-southeast direction along the Iowa western border and Nebraska is the state west of Iowa. The Des Moines River flows in a south-southeast direction from the figure 1 north center edge to Des Moines and then in a southeast direction to the figure 1 east edge (just north of the state line near the figure 1 southeast corner). East of the figure 1 map area the Des Moines River flows to the south-oriented Mississippi River, which in turn flows to the Gulf of Mexico. Labeled Des Moines River tributaries of importance in this essay include the North Raccoon River and Middle River. The North Raccoon River on figure 1 is joined west of Des Moines by several unlabeled southeast and east oriented tributaries to form the east-oriented Raccoon River, which joins the Des Moines River at Des Moines. The westernmost of those unlabeled southeast and east oriented tributaries (which flows near Guthrie Center) is the South Raccoon River, which forms the northeast boundary of the study region for this essay. The southeast and northeast oriented Middle River originates north of Adair and joins the Des Moines River a short distance downstream from Des Moines. The Nishnabotna River is not labeled on figure 1 and has multiple southwest, south-southwest, and south oriented tributaries in southwest Iowa, which converge to form the south-oriented West Nishnabotna River and the southwest and south-southwest oriented East Nishnabotna River, which then join near Hamburg in the Iowa southwest corner to form the south-oriented Nishnabotna River, which finally flows to the south-southeast oriented Missouri River in the Missouri northwest corner. South-southwest and southwest oriented East Nishnabotna River headwaters are located in the region north of Adair, west of Guthrie, and south of Coon Rapids and present a marked contrast to the southeast-oriented Raccoon River tributaries just to the northeast. The Des Moines River-Nishnabotna River drainage divide area investigated here is located east of Audubon, south of Coon Rapids, west of Guthrie, and north of Adair and locally is the South Raccoon River and Middle River drainage divide with the East Nishnabotna River, but in a larger sense is also the Missouri River and the Mississippi River drainage divide.

• Drainage routes in the figure 1 map area evolved during immense south-oriented floods which flowed across the entire map region. Flood waters were derived from a rapidly melting thick North American ice sheet located (at the time the figure 1 drainage routes) evolved just north of the figure 1 map area. The ice sheet had been large, probably comparable in size to the present day Antarctic Ice Sheet, and had been located in a deep “hole”. The deep “hole” had been formed by a combination of deep glacial erosion and of crustal warping caused by the ice sheet’s great weight. The figure 1 map area is located along the southern rim of that deep “hole” and was probably deeply eroded by south-oriented melt water floods prior to development of present day drainage routes. Determination of how much flood water erosion occurred may never be possible nor may it be possible to correctly identify the maximum extent of the ice sheet’s southern advance(s). What can be determined is all modern valleys in the figure 1 map area eroded headward along and across immense south-oriented melt water floods flow routes. Initially flood waters probably moved in a south direction across the figure 1 map area with an unusually large concentration of south-oriented flood flow moving across eastern Nebraska. That large concentration of flood flow was emerging from a giant ice-walled (and later bedrock-floored) canyon carved into the decaying ice sheet’s surface. In South Dakota the east-facing Missouri Escarpment and the west-facing Prairie Coteau Escarpment are what remain of that giant canyon’s west and east walls. Escarpments and “coteau” type regions used to identify the giant canyon’s former location can be followed headward from South Dakota across North Dakota and Saskatchewan into Alberta, suggesting the river flowing on the canyon’s floor was draining a large region of the decaying ice sheet’s surface. Evidence describing that giant ice-walled and bedrock-floored canyon’s southern end is contained in essays listed under North Dakota and South Dakota and especially James River on the sidebar category list.

• The figure 1 drainage routes evolved as headward erosion of deep east and southeast oriented tributary valleys eroded headward in sequence from south to north and from east to west and captured the south oriented melt water flood flow and diverted the flood waters to what was probably an actively eroding Mississippi River valley, which was eroding headward from the Gulf of Mexico. Headward erosion of the deep Mississippi River valley and its deep east and southeast oriented tributary valleys also caused south oriented flood waters in many regions to flow in south-southeast and southeast directions toward the actively eroding deep valley heads. Headward erosion of the deep Missouri River valley across the state of Missouri (south of the figure 1 map area) enabled south and southeast-oriented Missouri River tributary valleys to erode headward into southern Iowa and also captured the large melt water river emerging from the previously mentioned giant ice-walled canyon, which then eroded the south-southeast oriented Missouri River valley headward across the figure 1 map area. At the same time headward erosion of deep southeast-oriented Des Moines River valley and its tributary valleys was capturing south- and southeast-oriented flood flow in eastern and central Iowa and beheading flood flow routes to actively eroding south-oriented Missouri River tributary valleys. The South Raccoon (and Middle) River-East Nishnabotna River drainage divide in the Audubon and Guthrie County area was formed as headward erosion of the East Nishnabotna River valley and tributary valleys beheaded southeast-oriented flood flow routes to actively eroding South Raccoon and Middle River tributary and headwaters valleys and also as South Raccoon River and tributary valley headward erosion beheaded flood flow routes to actively eroding East Nishnabotna tributary and headwaters valleys.

• Figure 2 provides a somewhat more detailed location map for the Des Moines River-Nishnabotna River drainage divide area in Audubon and Guthrie Counties, Iowa. County names and boundaries are shown. The Des Moines River flows in a southeast direction through Des Moines in the figure 2 northeast quadrant. The North Raccoon River flows in a south-southeast direction from the figure 2 north edge across central Dallas County to join the South Raccoon River near Van Meter (just north of Dallas County south center border) to form the east-oriented Raccoon River. The South Raccoon River originates just east of Viola Center in the Audubon County northeast quadrant and flows in a southeast direction across Guthrie County before turning to flow in an east-southeast and east direction to join the North Raccoon River near Van Meter. Brushy Creek is a southeast oriented South Raccoon River tributary which flows from the figure 2 north edge to the Guthrie County northwest corner and then to join the parallel South Raccoon River near Monteith (southeast of Guthrie Center). Note how the South Raccoon River in Guthrie County has several much shorter east-northeast oriented tributaries from the west and south. The Middle River originates in and flows in a southeast direction across the Guthrie County southwest quadrant and the Adair County northeast quadrant before turning to flow in an east-northeast direction across Madison and Warren Counties to join the Des Moines River near the Warren County northeast corner. Note how the Middle River, South Raccoon River, and other Raccoon River and Des Moines River tributaries in the Guthrie and Dallas County area flow as roughly parallel southeast oriented streams before turning to flow in east or east-northeast directions to join the southeast-oriented Des Moines River. The East Nishnabotna River originates just north of the figure 2 map area and flows in a southeast to the Audubon County north center border and then towards Viola Center before turning to flow in a south and southwest direction to Atlantic in northwest Cass County before flowing to the figure 2 southwest corner area. Major southwest-oriented East Nishnabotna River tributaries in the study region include Davids Creek, which originates near Larland and which joins the East Nishnabotna River near Extra, and Troublesome Creek, which originates near North Branch in west-central Guthrie County and which joins the East Nishnabotna River near Atlantic. South-oriented drainage in western Adair County represents headwaters of the south-southwest oriented Middle Nodaway River, which flows to the south-oriented Nodaway River, which is a Missouri River tributary located east of the Nishnabotna River drainage basin. The south-southeast-oriented Thompson River in southeast Adair County, Madison County southwest corner, and eastern Union County, flows to the southeast- and south-oriented Grand River, which eventually joins the Missouri River. The West Nodaway River-Platte River drainage divide area landform origins in Page, Taylor, Ringgold, and Adams Counties, essay describes the region located south and west of the region discussed here, and the Boyer River-Nishnabotna River drainage divide area landform origins in Crawford, Carroll, Shelby, and Audubon Counties essay describes the region  located north and west of the study region discussed here. Essays discussing other Iowa drainage divide areas can be found listed under Iowa or IA Missouri River on the sidebar category list.

• Figure 3 provides a reduced size topographic map of the East Nishnabotna River-South Raccoon River drainage divide area near Viola Center. Coon Rapids is the town near the figure 3 northeast corner and is located on the south-southeast oriented Middle Raccoon River. Brushy Creek is the southeast-oriented stream flowing from the figure 3 north center edge to the east edge (just north of the southeast corner). Viola Center is labeled as a place-name south of the figure 3 center. Beaver Creek is the labeled northeast-oriented Brushy Creek tributary located north of Viola Center. Note how Beaver Creek has a northwest-oriented (barbed) tributary. The southeast-oriented South Raccoon River originates in the region east of Viola Center and flows to the figure 3 southeast corner. The East Nishnabotna River flows in a southeast direction from the figure 3 west edge (north half) towards Viola Center, but then turns to flow in a south direction before turning again to flow in a southwest direction to the figure 3 south edge (west half). Note how northwest-oriented barbed tributaries join the East Nishnabotna River at both of the elbows of capture where the East Nishnabotna River changes its direction of flow. One tributary has southeast-oriented headwaters originating just south of Viola Center and which turn to flow in a southwest, south, and northwest direction to join the East Nishnabotna River. Also note northwest-oriented headwaters and tributaries of East Nishnabotna River tributaries located in the figure 3 northwest quadrant. Study of the figure 3 map area reveals a number of northwest-southeast oriented through valleys linking northwest-oriented tributary valleys with southeast-oriented valleys. For example, near the figure 3 north edge, west of the highway west of Brushy Creek, a northwest-oriented Brushy Creek tributary valley (joining Brushy Creek north of figure 3) is linked by shallow through valleys with an east oriented Brushy Creek tributary valley and also with an east and southeast-oriented Beaver Creek tributary valley. Figure 4 below provides a detailed map of the Beaver Creek-South Raccoon River drainage divide area north of Viola Center to better illustrate shallow through valleys in that region. The unlabeled south-oriented stream near the figure 3 south center edge and south of the South Raccoon River headwaters area is the headwaters of southwest-oriented Davids Creek (better seen in figures 5 and 6) and through valleys south of Viola Center link the Davids Creek headwaters valley with northwest-oriented East Nishnabotna River tributary valleys. The northwest-oriented valleys were eroded by reversals of flood flow on beheaded southeast-oriented flood flow routes. The figure 3 map evidence suggests headward erosion of the East Nishnabotna River valley beheaded and reversed flood flow to the Davids Creek valley and to some South Raccoon River headwaters valleys while Brushy Creek-Beaver Creek valley headward erosion beheaded and reversed additional flood flow routes to South Raccoon River headwaters valleys.

• Figure 4 provides a more detailed topographic map of the East Nishnabotna River-South Raccoon River drainage divide near Viola Center and seen in less detail in the figure 3 map above. Viola Center is the small community located in the figure 4 south center area. The East Nishnabotna River flows in a southeast direction from the figure 4 northwest corner to the west center area before turning to flow in a south direction to the figure 4 south edge (west half). The South Raccoon River originates in section 15 (north of Viola Center) and flows in an east-northeast direction before turning to flow in a south-southeast direction to the figure 4 east edge (south half). The east-northeast oriented stream originating near the north edge of the section 15 northeast quadrant and turning to flow in a northwest direction in section 11 to flow across section to the figure 4 north edge is a Beaver Creek tributary. Note how the valley of that northwest-oriented Beaver Creek tributary is linked by through valleys with the south-southeast oriented South Raccoon River valley. The map contour interval is 20 feet and the deepest through valley is defined by two contour lines on each side. While not deep the through valleys provide evidence of southeast-oriented flood flow routes to what was at one time the actively eroding South Raccoon River valley. Headward erosion of the deep Brushy Creek-Beaver Creek valley beheaded the southeast-oriented flood flow and flood waters on the northwest end of the beheaded flood flow route reversed flow direction to erode the northwest-oriented Beaver Creek tributary valley. Further south in sections 27 and 28, just south of Viola Center, another northwest-southeast oriented through valley can be seen linking a northwest-oriented East Nishnabotna River tributary valley with a south-southeast oriented stream in section 27. South of the figure 4 map area, as seen in figure 3, that south-southeast oriented stream turns to flow in a southwest, south, and northwest direction to join the East Nishnabotna River. However, just south of the figure 4 map area that stream has a northwest-oriented tributary, which is linked by a northwest-southeast oriented through valley with the northeast-oriented South Raccoon River tributary seen in the figure 4 southeast corner. Study of mosaics of detailed topographic maps reveals many other such barbed tributaries, elbows of capture, and through valleys crossing present day drainage divides. The barbed tributaries, elbows of capture, and through valleys, along with the valley orientations, provide evidence of southeast-oriented flood flow routes captured by headward erosion of the deep East Nishnabotna River, South Raccoon River, Brushy Creek and tributary valleys.

• Figure 5 provides a topographic map of the South Raccoon River-Davids Creek drainage divide area south of the figure 3 map area and includes overlap areas with figure 3. Audubon is the town straddling the figure 5 west edge (south half). Viola Center is located near the figure 5 north center edge. The East Nishnabotna River is located in the figure 5 west half and flows in a south, southwest, and south direction from the north edge to the south edge. The South Raccoon River flows from the Viola Center area in a southeast direction across the figure 5 northeast quadrant. Brushy Creek is the southeast-oriented stream flowing in the figure 5 northeast corner area. Davids Creek is the south-southwest, south-southeast, and southwest oriented stream flowing from the figure 5 center to the south center edge. Note how in the figure 5 center area a north and southeast oriented Davids Creek tributary is linked by a northwest-southeast oriented through valley with a northwest-oriented East Nishnabotna River tributary valley. The map contour interval is ten meters and the through valley floor elevation is between 420 and 430 meters. Elevations to the southwest rise to more than 460 meters while elevations to the northeast rise to at least 450 meters. The grid lines on the map define one mile square sections and the distance between high points on both sides of the through valley appears to be almost three miles. The through valley was eroded by southeast-oriented flood flow moving to what was then the actively eroding Davids Creek valley prior to headward erosion of the deep south- and southwest-oriented East Nishnabotna River valley in the figure 5 northwest quadrant. Headward erosion of the deep East Nishnabotna River valley beheaded the southeast-oriented flood flow route to the newly eroded Davids Creek valley. Flood waters on the northwest end of the beheaded flood flow route reversed flow direction to erode the northwest-oriented East Nishnabotna River tributary valley. Tributary valleys to that northwest-oriented tributary valley were eroded as the reversed flood flow captured flood waters from the surrounding region. While not as deep shallow through valleys also link the south-oriented Davids Creek headwaters valley with the valleys of northeast and north-northeast oriented South Raccoon River tributary valleys north of Larland. These through valleys are generally defined by a single ten meter contour line on each side, but provide evidence headward erosion of the southeast-oriented South Raccoon River valley and its northeast and north-northeast oriented tributary valleys beheaded south-oriented flood flow moving to the Davids Creek valley. Figure 6 below provides a detailed topographic map to better illustrate those through valleys.

• Figure 6 provides a detailed topographic map of the South Raccoon River-Davids Creek drainage divide area seen in less detail in figure 5 above. The southeast-oriented South Raccoon River is located in the figure 6 northeast corner. West-oriented streams flowing to the figure 6 west edge are East Nishnabotna River tributaries (see figure 5). Davids Creek is the stream in the figure 6 south center area originating in the section 2 east center area and flowing across the section 1 southwest corner and then south to the figure 6 south edge in section 12. Note how in section 1 the south-oriented Davids Creek valley is linked by a north-south oriented through valley with a north and northeast oriented South Raccoon River tributary valley. The map contour interval is 20 feet and the through valley floor elevation is between 1400 and 1420 feet. Elevations west of the through valley rise to at least 1460 feet while to the east elevations rise to more than 1440 feet. The through valley provides evidence of a south-oriented flood flow route to the Davids Creek valley prior to headward erosion of the northeast-oriented South Raccoon River tributary valley in the section 36 northeast quadrant. At that time there was no deep South Raccoon River valley north of section 36. Headward erosion of the South Raccoon River valley and its northeast-oriented tributary valley into the section 36 northeast quadrant beheaded and reversed flood flow to erode the north oriented tributary valley segment. The question might be asked, where did the volumes of water required to erode the deep north and northeast oriented tributary valley come from? Look in the south half of section 35 and there is a west to east oriented through valley linking the headwaters of the north and northeast-oriented South Raccoon River tributary valley with headwaters of a west-oriented East Nishnabotna River tributary valley. The section 35 through valley is not quite as deep as the north-south oriented through valley in section 1, but provides evidence of east-oriented flood flow to the north- and northeast-oriented South Raccoon River tributary valley prior to the reversal of flood flow that eroded the west-oriented East Nishnabotna tributary valley. Study of the figure 6 map area and of adjacent regions reveals many other through valleys indicating a complex pattern of flood flow movements. The example discussed here needs to be considered in the context of those other flood flow movements, a full discussion of which is beyond the scope of the descriptions being provided here.

• Figure 7 provides a topographic map of the Troublesome Creek-Middle River drainage divide area located south and east of the figure 5 map area. Davids Creek flows in a southwest direction across the figure 7 northwest corner. Note northwest oriented Davids Creek tributaries from the southeast and south-southeast oriented tributaries from the north. The south-southwest oriented stream flowing to the figure 7 southwest corner is Troublesome Creek. Troublesome Creek, like Davids Creek, is a tributary to the south-oriented East Nishnabotna River, which is located a short distance west of the figure 7 map area. Note how Troublesome Creek also has northwest oriented tributaries from the east and southeast and south-southeast oriented tributaries from the west. The southwest-oriented stream in the east half of the figure 7 southwest quadrant is Crooked Creek, which will be better seen in figures 9 and 10. The southeast-oriented river flowing to the figure 7 southeast corner is the Middle River, which as seen in figures 1 and 2 flows in a southeast and east-northeast direction to eventually join the southeast-oriented Des Moines River. Casey is the town located near the figure 7 southeast corner and the South Fork is the tributary joining the Middle River near Casey. Guthrie Center is the town located near the figure 7 northeast corner and the southeast-oriented South Raccoon River is located at Guthrie Center. The labeled northeast-oriented tributary joining the South Raccoon River just upstream from Guthrie Center (and north of the figure 7 map area) is Seely Creek and the labeled east- and north-oriented tributary joining the South Raccoon River just south of Guthrie Center (in the map area) is Mason Creek. Note how Mason Creek has north-oriented tributaries and flows to the southeast-oriented South Raccoon River as a north-oriented stream. Note also shallow through valleys linking northwest and west oriented Troublesome Creek tributary valleys with east-oriented Seely Creek and Mason Creek headwaters valleys and also with the southeast-oriented Middle River headwaters valley. The through valleys provide evidence headward erosion of the south-southwest oriented Troublesome Creek valley beheaded east-oriented flood flow routes to South Raccoon River tributary valleys and to the Middle River valley. The northwest and west-oriented Troublesome Creek tributary valley was eroded by a reversal of flood flow. The Troublesome Creek-Middle River drainage divide can be identified by the south-southeast intermittent areas of elevations greater than 450 meters extending across the Guthrie County southwest corner. Note how the deep Troublesome Creek valley eroded headward across that south-southeast “ridge” of higher elevations and on the northeast side has significant northwest and southeast-oriented tributary drainage basins. This evidence suggests flood waters once flowed on a surface at least as high as the highest figure 7 elevations today.

• Figure 8 provides a detailed topographic map of the Troublesome Creek-Middle River drainage divide area seen in less detail in figure 7 above. Troublesome Creek is labeled and is located in the figure 8 west half where it flows in a north-northeast, northwest, and southwest direction to the figure 8 west edge. Note northwest-oriented tributaries especially in sections 26 and 27. The Middle River flows in a north-northeast direction from the figure 8 south center edge to sections 35 and 36 where it turns to flow in a south-southeast  and east direction to the figure 8 southeast corner. Note southeast-oriented tributaries especially in sections 34, 35, and 36. Another figure 8 labeled stream is Mason Creek in the northeast quadrant. As seen in figure 7 Mason Creek is a South Raccoon River tributary. Note how the east-oriented Mason Creek headwaters are linked by a shallow through valley in the section 26 northeast quadrant with a northwest-oriented Troublesome Creek tributary valley. Follow the drainage divide in a southwest direction from section 26 into sections 35, 25, and 6 and note the multiple shallow through valleys linking the north-northeast oriented Troublesome Creek valley with the north-northeast oriented Middle River valley segment.The through valleys provide evidence the north-northeast oriented Middle Creek valley segment captured multiple southeast-oriented flood flow routes prior to headward erosion of the north-northeast oriented Troublesome Creek valley. Because today the north-northeast oriented Troublesome Creek valley drains to the south-southwest Troublesome Creek located to the northwest, when first eroded the north-northeast oriented Troublesome Creek valley segment probably drained in an east direction to the Mason Creek valley and then to the South Raccoon River valley. However, headward erosion of the deep south-southwest oriented Troublesome Creek valley to the northwest beheaded a southeast-oriented flood flow route to the Mason Creek valley. Flood waters on the northwest end of that beheaded flood flow route reversed flow direction and eroded the northwest-oriented Troublesome Creek valley segment, which captured the north-northeast oriented Troublesome Creek headwaters valley as flood waters drained from the region. Study of the figure 8 map area reveals additional through valleys providing evidence of further flood flow movements across the figure 8 map region.

• Figure 9 illustrates the Crooked Creek-South Fork Middle River drainage divide area located south of the figure 7 map area and includes some overlap with figure 7. Troublesome Creek flows in a southwest direction across the figure 9 northwest corner. Note northwest-oriented Troublesome Creek tributaries from the southeast and southeast oriented tributaries from the northwest. Crooked Creek is the southwest-oriented stream flowing from the figure 9 north center area to the figure 9 west edge (south half). Note how Crooked Creek originates on the northwest-southeast oriented drainage divide extending from the figure 9 north edge (west half) to the south edge (east half). Also note northwest-oriented Crooked Creek tributaries from the southeast and south and southeast oriented tributaries from the north and west. Study of the Troublesome Creek-Crooked Creek drainage divide reveals through valleys linking northwest-oriented Troublesome Creek tributary valleys with south and southeast oriented Crooked Creek tributary valleys. For example south of Kenfield in the figure 9 northwest quadrant a well-defined through valley links a south-oriented Crooked Creek tributary valley with a northwest-oriented Troublesome Creek tributary valley (seen in more detail in figure 10 below). Adair is the town located near the figure 9 center and Anita is the town near the southeast corner. The southwest-oriented stream flowing to the figure 9 southwest corner is Turkey Creek. Note how Turkey Creek has southeast- and south-oriented headwaters west of Adair. Also note south-oriented Turkey Creek tributaries from the north and northwest-oriented Turkey Creek tributaries from the southeast. Again study of the Crooked Creek-Turkey Creek drainage divide reveals shallow through valleys linking northwest-oriented Crooked Creek tributary valleys with south-oriented Turkey Creek tributary valleys. Casey is the town located in the figure 9 east center area. The east-southeast oriented stream at Casey is the South Fork (Middle River) which joins the southeast-oriented Middle River just east of Casey. Note how the South Fork headwaters are oriented in a northwest direction and have southeast-oriented tributaries in the region east of Adair. This complex drainage pattern with barbed tributaries and elbows of capture resulted from the beheading and reversal of southeast-oriented flood flow routes. The south-oriented streams flowing to the figure 9 south edge are headwaters of Nodaway River tributaries, with the Nodaway River being a south-oriented Missouri River tributary located east of the Nishnabotna River. Figure 9 evidence documents Turkey Creek valley headward erosion from what was then the newly eroded East Nishnabotna River valley beheaded flood flow to the Nodaway River drainage basin and South Fork valley headward erosion from the newly eroded Middle River valley also beheaded and reversed flood flow to the Nodaway River drainage basin. The Missouri River (Nishnabotna and Nodaway Rivers)-Mississippi River (Middle River) drainage divide was created as deep valleys eroded headward into the figure 9 map area to capture the southeast-oriented flood flow.

• Figure 10 provides a detailed topographic map of the Troublesome Creek-Crooked Creek drainage divide area south of Kenfield which was seen in less detail in figure 9 above. Kenfield is the name for the cluster of buildings located near the corner of sections 1, 2, 11, and 12 in the figure 10 northwest quadrant. The west and west-northwest oriented streams flowing to the figure 10 west edge are Troublesome Creek tributaries. The east and northeast oriented streams flowing to the figure 10 east edge are Middle River tributaries. The south-oriented streams flowing to the figure 10 south edge are Crooked Creek tributaries. Remember Troublesome Creek and Crooked Creek flow to the East Nishnabotna River, which is included in the Missouri River drainage basin and the Middle River is a Des Moines River tributary, meaning the Des Moines River-Missouri River drainage divide extends from west of section 6 across the section 7 northeast corner and diagonally across section 8 and then south near the section 17 east margin. Note how in section 8 shallow through valleys provide evidence of multiple flood flow routes between a southwest and south oriented Crooked Creek tributary valley and an east (and east of the figure 10 map area northeast) oriented Middle River tributary valley. The through valleys provide evidence flood waters once flowed from the present day Des Moines River drainage basin to what was then the newly eroded Missouri River valley. Headward erosion of the deep east-oriented Middle Creek tributary valley beheaded south-oriented flood flow moving to what was then the actively eroding south-oriented Crooked Creek tributary valley. South of Kenfield in section 12 a deeper through valley links the west-northwest oriented Troublesome Creek tributary valley with the south-oriented Crooked Creek tributary valley. The map contour interval is 20 feet and the through valley floor elevation is between 1420 and 1440 feet. Elevations on either side of the through valley rise to more than 1480 feet. The through valley provides evidence of a south-oriented flood flow route to the south-oriented Crooked Creek tributary valley at a time prior to headward erosion of the deep Troublesome Creek valley north and west of the figure 10 map area. Troublesome Creek valley headward erosion beheaded and reversed the southeast and south oriented flood flow route to erode the west-northwest oriented Troublesome Creek tributary valley. Study of the figure 10 map area and of adjacent regions reveals many other through valleys providing evidence of additional flood flow routes and of additional capture and flood flow reversal events.

Additional information and sources of maps studied