The Little Nemaha River-Big Nemaha River drainage divide area is located in the Nebraska southeast corner and was eroded by an immense southeast and south oriented flood at the time the Missouri River valley and its tributary valleys were first eroding headward into Nebraska. The Big Nemaha River valley and its tributary Muddy Creek valley eroded headward from the actively eroding Missouri River valley head to capture southeast and south oriented flood water west of the newly eroded Missouri River valley. Headward erosion of the Missouri River valley and its tributary Little Nemaha River valley then beheaded many flood flow routes to the newly eroded Muddy Creek and Big Nemaha River valleys. Finally headward erosion of the Missouri River valley and its tributary Platte River-Salt Creek valley beheaded all remaining flood flow routes to the newly eroded Big Nemaha River and Little Nemaha River valley systems. Topographic map evidence supporting this drainage history interpretation include barbed tributaries, elbows of capture, valley orientations, and numerous through valleys across present day drainage divides.

• The purpose of this essay is to use topographic map interpretation methods to explore Little Nemaha River-Big Nemaha River drainage divide area landform origins in southeastern Nebraska, 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 Missouri River drainage basin landform origins research project essays 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 Little Nemaha River-Big Nemaha River drainage divide area landform origins in southeastern Nebraska will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Little Nemaha River-Big Nemaha River drainage divide area location map

Figure 1: Little Nemaha River-Big Nemaha River drainage divide area location map. National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 is a location map for the Little Nemaha River-Big Nemaha River drainage divide area in southeastern Nebraska. Nebraska is the state in the figure 1 northwest area, Kansas is located south of Nebraska. The Missouri River flows in a south-southeast direction from the figure 1 north center edge to the figure 1 south edge. East of the Missouri River in the figure 1 northeast area is Iowa and south of Iowa is Missouri. The Platte River is located in Nebraska and flows from the figure 1 west edge in a northeast direction to Columbus and North Bend. At North Bend the Platte River begins to turn in a south direction and flows in south direction from Fremont to Ashland where the P{latte River turns again to flow in a east-northeast direction to join the Missouri River. A significant, but unlabeled Platte River tributary is Salt Creek, which flows in a northeast direction from Lincoln to join the Platte River near Ashland (actually Salt Creek joins southeast-oriented Wahoo Creek, which then flows to the Platte River). The Little Nemaha River is the unlabeled southeast-oriented stream, located southeast of Lincoln, which flows through Palmyra, Syracuse, Talmage, and Auburn before reaching the Missouri River. The Big Nemaha River is located south of the Little Nemaha River and also flows in a southeast direction through Adams, Sterling, Tecumseh, Humboldt, Dawson, and Falls City before joining the Missouri River near the Nebraska-Kansas state line. Northwest of the Little Nemaha River and Big Nemaha River headwaters area are northeast-oriented Salt Creek headwaters and tributaries. West of the Big Nemaha River drainage basin is the south-southeast oriented Big Blue River, which flows south into Kansas, where it joins the east-oriented Kansas River, which flows to join the Missouri River at Kansas City. Previous essays have addressed evidence in the Platte River-Missouri River drainage divide area immediately north of the Little Nemaha River, in the Platte River-Salt Creek drainage divide area and Platte River-Wahoo Creek drainage divide area both located northwest of the Little Nemaha River-Big Nemaha River drainage divide area (these cited essays can be found under Platte River on the sidebar category list). The hundreds of Missouri River drainage basin landform origins research project essays published on this website have presented overwhelming evidence for immense south- and southeast-oriented floods, which probably flowed from a rapidly melting thick North American ice sheet into and across Nebraska. The Missouri River valley and its tributary valleys eroded headward into the figure 1 map area to systematically capture this massive south- and southeast-oriented flood water. South and southeast oriented flood flow to what were the actively eroding Big and Little Nemaha River valley systems was finally beheaded by Platte River-Salt Creek valley headward erosion.

Little Nemaha River-Big Nemaha River drainage divide area detailed location map

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

Figure 2 provides a slightly more detailed location map for the Little Nemaha River-Big Nemaha River drainage divide area. The south-southeast oriented Missouri River is located in the figure 2 east half and flows to the figure 2 southeast corner. The Iowa southwest corner is located in the figure 2 northeast quadrant (east of the Missouri River). The Missouri northwest corner is located south of the Iowa southwest corner and east of Missouri River. Nebraska is located west of the Missouri River, although the Nebraska-Kansas state line can be seen near the figure 2 south edge. Lancaster, Otoe, Gage, Johnson, Pawnee, Nemaha, and Richardson are Nebraska county names and the county boundaries are shown. The Big Blue River flows in a south-southeast direction from the figure 2 northwest corner into Gage County and then south to the figure 2 south edge. The Little Nemaha River originates near Bennet in eastern Lancaster County and flows in an east-northeast direction to Palmyra before turning to flow in a southeast direction to Unadilla, Syracuse, Talmage, Brock, Glenrock, and Auburn before joining the Missouri River near Nemaha. The South Fork Little Nemaha River originates near Douglas in the Otoe County southwest corner and flows in a southeast direction into northern Johnson County before turning to flow in a northeast direction to join the southeast-oriented Little Nemaha River in southern Otoe County. Spring Creek is a north-oriented Little Nemaha River tributary originating in northeast Johnson County. The Big Nemaha River originates south of Lincoln in southern Lancaster County and flows through Firth before flowing to Adams in the Gage County northeast corner. From Adams the Big Nemaha River flows to Sterling in northwest Johnson County and then flows in a southeast direction to Tecumseh, Elk Creek, Humboldt, Dawson, and Falls City before flowing to join the Missouri River near the figure 2 southeast corner. The North Fork Big Nemaha River originates in the Lancaster County southeast corner and flows in a southeast direction to join the Big Nemaha River near Sterling. Long Branch is a southeast-oriented Big Nemaha River tributary joining the Big Nemaha River near Humboldt in western Richardson County. Muddy Creek is southeast-oriented Big Nemaha River tributary flowing across the Nemaha County southwest corner and then across Richardson County to join the Big Nemaha River east of Falls City.

Salt Creek-Big Nemaha River drainage divide area

Figure 3: Salt Creek-Big Nemaha River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Salt Creek-Big Nemaha River drainage divide area and also the Little Nemaha River headwaters area south and southeast from Lincoln, Nebraska. The Little Nemaha River is located along the figure 3 north edge in the figure 3 northeast quadrant and the South Fork Little Nemaha River flows to the figure 3 east center edge. The Salt Creek drainage basin is located in the figure 3 northwest quadrant and also in the figure 3 north enter area. Salt Creek flows in a northeast direction to Roca, where it joins northwest oriented Hickman Branch and then flows in a northwest direction to the figure 3 north edge. Hickman Branch headwaters are in the figure 3 center and Hickman Branch flows in a west direction before turning near Hickman to flow in a northwest direction to join Salt Creek. North of the figure 3 map area Salt Creek turns to flow in a northeast direction to join Wahoo Creek and the Platte River. Note the south-southeast oriented Hickman Branch tributary flowing from the figure 3 north edge to Wagon Train Lake. Also note the north-northwest oriented tributary joining Hickman Branch in the figure 3 center area (just southeast from Hickman). Orientations of those Hickman Branch tributaries and northwest Hickman Branch and Salt Creek valley segments provide evidence the Salt Creek valley eroded headward to capture multiple south-southeast oriented flood flow channels. Northwest and north-northwest oriented valley segments were eroded by flood flow reversals on north ends of beheaded south-oriented flood flow channels. The south-southeast oriented Hickman Branch tributary (flowing to Wagon Train Lake) is on the same alignment as the southeast-oriented North Fork Big Nemaha River, which flows to the figure 3 southeast corner. Also the north-northwest oriented Hickman Branch tributary is linked by a through valley with southeast-oriented Big Nemaha River headwaters at Firth (located in the figure 3 south center). What has happened is prior to the northeast-oriented Salt Creek valley headward erosion (north of the figure 3 map area) south-southeast flood waters flowed across the entire figure 3 map area, probably to what was then the actively eroding Missouri River valley head. Headward erosion of the southeast-oriented Big Nemaha River valley and its North Fork valley then entered the figure 3 map area and flood flow moved in south-southeast oriented channels to those actively eroding valleys. Headward erosion of the Salt Creek valley (north of figure 3) then beheaded the south-southeast oriented flood flow channels causing reversals of flood flow on north ends of the flood flow channels. The northwest-oriented Salt Creek valley segment and Hickman Branch drainage systems were eroded by such flood flow reversals, which also captured the south-southeast oriented tributary flowing to Wagon Train Lake.

South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area

Figure 4: South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area north of Tecumseh and south and east from the figure 3 map area. Tecumseh is the city located along the figure 4 south edge. The North Fork Big Nemaha River flows in a southeast direction across the figure 4 southwest corner. The South Fork Little Nemaha River is labeled and is located along the figure 4 north edge. North of the figure 4 map area the South Fork flows to the southeast-oriented Little Nemaha River. Northeast-oriented streams in the figure 4 northeast corner are Little Nemaha River tributaries. Muddy Creek is the northeast and southeast-oriented stream in the figure 4 southeast quadrant. West of Muddy Creek is north and north-northeast oriented Spring Creek, which flows to the Little Nemaha River. The north-northeast and east oriented Spring Creek tributary originating north of Tecumseh is Manns Branch. West of Manns Branch is northeast and northwest oriented Coon Creek. Turkey Creek is the northeast-oriented South Fork tributary west of Coon Creek and Silver Creek is the northeast-oriented South Fork tributary west of Turkey Creek.  Close study of the figure 4 map evidence reveals north-south oriented through valleys linking north oriented South Fork Little Nemaha River tributary valleys with south oriented North Fork Big Nemaha River tributary valleys. For example south oriented Town Branch, which flows to the North Fork Big Nemaha River at Tecumseh is linked by a through valley with a north oriented Coon Creek tributary (figure 5 below illustrates that through valley in more detail). Further west other shallow north-south oriented through valleys link the Coon Creek and Turkey Creek headwaters valleys with short south-oriented North Fork Big Nemaha River tributary valleys. These shallow through valleys provide evidence of multiple south-oriented flood flow channels moving flood waters across a topographic surface at least as high the present day South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide today. Flood waters were first captured by headward erosion of the southeast-oriented North Fork Big Nemaha River valley. South-oriented tributary valleys eroded into the North Fork north wall are short, suggesting headward erosion of South Fork Little Nemaha River north- and northeast-oriented tributary valleys occurred shortly after erosion of the North Fork Big Nemaha River valley. A close look at drainage divides between the South Fork Little Nemaha River tributary valleys also reveals northwest-southeast oriented through valleys, suggesting flood waters were flowing in a southeast direction, which means tributary valleys eroded headward in sequence (from east to west).

Detailed map of South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area

Figure 5: Detailed map of South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 provides a detailed map of South Fork Little Nemaha River-North Fork Big Nemaha River drainage divide area north of Tecumseh, which was seen in less detail in figure 4 above. Town Branch originates in section 8 in the figure 5 west center area and flows in a southeast direction into section 16 where it turns to flow in south direction to the figure 5 south edge and then to join the North Fork Big Nemaha River at Tecumseh (see figure 4). North-oriented drainage in section 5 (north of the Town Branch headwaters) flows to northeast and northwest oriented Coon Creek, which flows to the South Fork Little Nemaha River. Note the two separate north-south oriented through valleys linking the north-oriented Coon Creek tributary valleys with the south oriented Town Branch valley. Another north-south oriented through valley in the section 9 northwest corner links another north-oriented Coon Creek tributary valley with a south-oriented Town Branch tributary valley. Further east in section 3 (just east of Tecumseh Airport) is the northeast-oriented Manns Branch valley, which drains in a northeast and east direction to north-oriented Spring Creek (which flows to the southeast oriented Little Nemaha River). Note a north-south oriented through valley in the section 15 northwest corner linking the Manns Branch headwaters valley with a south-oriented Town Branch tributary valley. Southeast-oriented drainage in the figure 5 southeast quadrant flows to north-oriented Spring Creek (located east of the figure 5 map area). Note in section 10 shallow northwest-southeast oriented through valleys linking the northeast-oriented Manns Branch valley with the southeast oriented Spring Creek tributary valleys. A close study of figure 5 reveals many more such through valleys. The through valleys in many case are subtle features, but they exist and were eroded by running water prior to headward erosion of the present day deeper valleys. The through valleys are best explained as channels eroded by an immense southeast and/or south oriented anastomosing channel complex, which was eroded into a topographic surface at least as high as the highest figure 5 elevations today. Headward erosion of the North Fork Big Nemaha River valley and its Town Branch tributary valley first captured the flood water. The north-oriented Spring Creek valley (east of the figure 5 map area) probably originated as a south-oriented flood flow channel moving water to the newly eroded Big Nemaha River valley and was later reversed to flow north. Headward erosion of the Little Nemaha River-South Fork valley next beheaded the south-oriented flood flow channels. Flood waters on the north ends of the beheaded flood flow channels reversed flow direction to flow north to the newly eroded Little Nemaha River valley and created the South Fork Little Nemaha-North Fork Big Nemaha River drainage divide.

Spring Creek-Long Branch drainage divide area

Figure 6: Spring Creek-Long Branch drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Spring Creek-Long Branch drainage divide area east and south of the figure 4 map area and includes overlap areas with figure 4. Tecumseh is the town located near the figure 6 west edge. Johnson is the smaller town in the figure 6 northeast quadrant (near the north edge). The North Fork Big Nemaha River flows in a southeast direction from Tecumseh to the figure 6 south edge. East of the southeast-oriented North Fork is southeast-oriented Long Branch, which flows to the figure 6 south center edge and eventually joins the southeast-oriented North Fork Big Nemaha River. North of the Long Branch headwaters are northwest-oriented headwaters of north-oriented Spring Creek, which flows north to the southeast-oriented Little Nemaha River valley. The northeast and southeast oriented stream east of north-oriented Spring Creek is Muddy Creek, which makes an abrupt turn at the figure 6 north edge (just west of Johnson) to flow in a southeast direction to the figure 6 east center edge. Southeast of the figure 6 map area Muddy Creek eventually joins the Big Nemaha River (see figure 9a below). Figure 6 map evidence for southeast-oriented flood flow is easier to see in the form of the multiple southeast-oriented valleys used by present day drainage routes. Through valleys linking the modern-day drainage routes are also present. The most obvious through valley links the northwest-oriented Spring Creek headwaters valley with the southeast-oriented Long Branch valley (figure 7 below provides a more detailed map of that through valley). The through valley provides evidence the present day north-oriented Spring Creek valley was initiated as a south-oriented flood flow channel feeding flood water to what was then the actively eroding Long Branch valley. Headward erosion of the Little Nemaha River valley north of the figure 6 map area beheaded the south-oriented flood flow channel moving water to the actively eroding Long Branch valley. Flood waters on the north end of the beheaded flood flow channel reversed flow direction to flow north to the newly eroded Little Nemaha River valley. Shallow through valleys can also be seen between the short northwest-oriented Spring Creek tributary valleys and the northeast-oriented Muddy Creek valley segment located in the figure 6 north center area. These through valleys provide evidence flood waters were spilling from the south-oriented flood flow channel in a southeast direction to what was then an actively eroding northeast-oriented tributary to the newly eroded southeast-oriented Muddy Creek valley

Detailed map of Spring Creek-Long Branch drainage divide area

Figure 7: Detailed map of Spring Creek-Long Branch drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed map of the Spring Creek-Long Branch drainage divide area seen in less detail in figure 6 above. West and northwest oriented Spring Creek headwaters are located in the figure 7 north center area. Long Branch originates in section 32 and drains south to section 5 and then in a southeast direction to the figure 7 south edge. Note shallow through valleys in section 32 linking the northwest-oriented Spring Creek headwaters valleys with the south-southeast oriented Long Branch valley. Another through valley can be seen along the border between section 31 and section 5 to the east. Southwest-oriented drainage in the figure 7 southwest quadrant flows directly to the southeast-oriented North Fork Big Nemaha River valley (south of the figure 7 map area). Through valleys in section 36 and section 25 link the North Fork Big Nemaha River tributary valleys with the north-oriented Spring Creek valley. These through valleys provide evidence that prior to headward erosion of the deep Little Nemaha River valley (north of the figure 7 map area) south-oriented flood water moved across a topographic surface at least as high as the present day Little Nemaha River-Big Nemaha River drainage divide today to what were then actively eroding North Fork Big Nemaha River tributary valleys. The southeast orientation of the Long Branch valley and the northwest orientation of the Spring Creek headwaters valley suggest there was a significant southeast-oriented flood water movement in addition to the south-oriented flood flow. Headward erosion of the deep Little Nemaha River valley north of the figure 7 map area beheaded the south-oriented flood flow routes. Flood waters on the north ends of the beheaded flood flow channels reversed flow direction to flow north to the newly eroded Little Nemaha River valley. This reversal of flood flow eroded the north-oriented Little Nemaha River tributary valleys and created the Little Nemaha River-Big Nemaha River drainage divide. Remember, headward erosion of the Little Nemaha River valley beheaded flood flow channels one channel at a time (from east to west). Also remember, the flood flow channels were anastomosing or interconnected, meaning reversed flood flow on a newly beheaded flood flow channel could easily capture yet to be beheaded flood flow from adjacent channels further to the west. Capture of such yet to beheaded flood flow provided the water volumes needed to eroded the north-oriented valleys.

South Fork Little Nemaha River-Muddy Creek drainage divide area

Figure 8: South Fork Little Nemaha River-Muddy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the South Fork Little Nemaha River-Muddy Creek drainage divide area north of the figure 6 map area and includes overlap areas with figure 6. The South Fork Little Nemaha River is located along the north edge in the figure 8 northwest quadrant. The southeast-oriented Little Nemaha River is located in the figure 8 northeast quadrant. Tecumseh is the town located just south of the figure 8 southwest corner. South-southeast oriented Town Branch flows near the west edge in the figure 8 southwest corner. North and north-northeast oriented Spring Creek flows from the figure 8 south edge to the figure 8 north center edge. Manns Branch is the north, northeast, and east-southeast oriented Spring Creek tributary in the figure 8 west center area. Ayres Branch is the northwest-oriented Spring Creek tributary joining Spring Creek just north of where Manns Branch joins Spring Creek. Muddy Creek flows in a northeast and southeast direction in the figure 8 south center area and then flows in a southeast direction to the figure 8 south edge. Muddy Creek continues to flow in a southeast direction parallel to the adjacent Little Nemaha River and North Fork Big Nemaha River valleys until almost reaching the Missouri River valley, where Muddy Creek joins the Big Nemaha River (see figure 9a below). Note the northwest-southeast oriented through valley linking a northwest-oriented tributary to northwest-oriented Ayres Branch (to Spring Creek) with the southeast-oriented Muddy Creek valley. Note also the northwest-southeast oriented through valley linking the South Fork Little Nemaha River valley with the east-southeast oriented Manns Branch valley. These through valleys provide evidence of a southeast-oriented flood flow channel that was systematically dismembered by headward erosion of the Little Nemaha River valley system. Initially the southeast-oriented flood flow channel may have split in the area where Manns Branch and Ayres Branch join Spring Creek today. One flood flow channel continued in a southeast direction to what was then the actively eroding Muddy Creek valley while the other channel led south to what was then the actively eroding Long Branch valley (such splits of channels are common in flood formed anastomosing channel complexes). The south-oriented channel may have eroded deeper and may have captured all of the flood flow, beheading the southeast-oriented flood flow route to Muddy Creek (it is possible the capture took place after Spring Creek was reversed). Whenever the channel to the Muddy Creek was beheaded flood waters on the northwest end of that channel reversed flow direction to erode the northwest-oriented Ayres Branch valley. Headward erosion of the Little Nemaha River valley next captured and reversed the south-oriented Spring Creek flood flow channel. Finally headward erosion of the South Fork Little Nemaha River valley beheaded the remaining southeast-oriented flood flow channel to the Manns Branch and north-oriented Spring Creek valley.

Little Nemaha River-Muddy Creek drainage divide area

Figure 9: Little Nemaha River-Muddy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Little Nemaha River-Muddy Creek drainage divide area just west of the Missouri River and south and east of the figure 8 map area. The south and southeast oriented Missouri River is located in the figure 9 northeast quadrant and flows to the figure 9 east edge. The southeast-oriented Little Nemaha River is located in the figure 9 north center edge area and flows to join the Missouri River just south of the town of Nemaha. Muddy Creek flows in a southeast direction from the figure 9 west center edge area to the figure 9 south edge. Stella is the town located in the Muddy Creek valley. Shubert is the town located east of Stella and in the figure 9 center area. The north-oriented Little Nemaha River tributary originating near Shubert is Whisky Run. The south-oriented Muddy Creek tributary originating near Shubert is Sardine Creek. Note the through valley at Shubert linking the two opposing streams (the north-south railroad made use of the through valley at Shubert and figure 10 below provides a more detailed map of the Shubert area). Howe is the small town in the figure 9 northwest corner area. The north-oriented Little Nemaha River tributary at Howe is Hughes Creek. Note the north-south oriented railroad line using the Hughes Creek valley and continuing south to Stella in the Muddy Creek valley. While not as obvious as the through valley at Shubert the railroad is located in another north-south oriented through valley. In fact most of the north-oriented Little Nemaha River tributaries are linked by through valleys with the southeast-oriented Muddy Creek valley. Further, note the north-oriented (barbed) Missouri River tributaries in the region immediately northeast from Shubert. Those north-oriented Missouri River tributaries are linked by through valleys with south-oriented Muddy Creek tributaries (located in the figure 9 southeast quadrant). The tributary orientations and the through valleys provide evidence the Muddy Creek valley eroded headward (to the northwest) from the actively eroding Missouri River valley head to capture multiple south-oriented flood flow channels. The Missouri River valley at the same time was eroded headward (north-northwest) and beheaded some of the south-oriented flood flow channels moving flood water to the newly eroded Muddy Creek valley. The Little Nemaha River valley then eroded headward from the actively eroding Missouri River valley head to capture more of the south-oriented flood flow channels to the newly eroded Muddy Creek valley. The north-oriented Missouri River and Little Nemaha River tributary valleys were eroded by reversals of flood flow on the north ends of the beheaded south-oriented flood flow channels. Figure 9a below illustrates the region immediately south of the figure 9 map area and shows where Muddy Creek joins the Big Nemaha River and the Big Nemaha River then flows to join the Missouri River.

Figure 9a: Muddy Creek-Big Nemaha Creek drainage divide area near Missouri River. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Detailed map of Little Nemaha River-Muddy Creek drainage divide area

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

Figure 10 provides a detailed map of the Shubert area seen in less detail in the figure 9 map area above. Shubert is the town located in the figure 10 center area. Whisky Run is the north oriented Little Nemaha River tributary originating just north of Shubert and flowing north to the figure 10 north edge. Sardine Creek is the south-oriented Muddy Creek (Big Nemaha River) tributary originating just south of Shubert and flowing south to the figure 10 south edge. A north-south oriented through valley is located along the east edge of Shubert and provides evidence of a south-oriented flood flow channel prior to headward erosion of the deep Little Nemaha River valley to the north. South-oriented flood waters were moving to what was then the actively eroding south-oriented Sardine Creek valley. Headward erosion of the Little Nemaha River valley beheaded the south-oriented flood flow channel. Flood waters on the north end of the beheaded channel reversed flow direction to flow north to newly eroded Little Nemaha River valley. Southeast from Shubert, in section 17 in the figure 10 southeast corner area, is another well-defined north-south through valley. The southeast and south oriented stream in the figure 10 southeast corner is Mackelroy Creek, which flows south to join Muddy Creek. The north-oriented stream originating in section 17 and flowing to the figure 10 northeast corner is Deroin Creek, which continues to flow north to join the southeast-oriented Missouri River as a barbed tributary. The Deroin Creek-Mackelroy Creek through valley not only provides evidence that south-oriented flood water once flowed across the present day drainage divide, but it also provides evidence the Muddy Creek valley-Mackelroy Creek valley had eroded headward prior to headward erosion of the Missouri River valley to the north of figure 10. In other words the Muddy Creek (and Mackelroy Creek) valley was being eroded at the same time the Missouri River valley was being eroded. At the time these valleys were being eroded in the figure 10 map area (and the larger area figure 9 and 9a map areas) the Missouri River valley and its tributary valley north and west of the Nebraska southeast corner did not exist. Instead the entire Missouri River drainage basin located north and west of the Nebraska southeast corner was being eroded by an immense southeast-oriented flood, with significant flood flow being directed towards the Nebraska southeast corner.

Additional information and sources of maps studied

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