A geomorphic history based on topographic map evidence

The Platte River-Wahoo Creek drainage divide area was eroded by a massive south-southeast oriented flood, with flood waters systematically captured by headward erosion of the Wahoo Creek valley and tributary valleys and subsequently captured by headward erosion of the Platte River valley. Flood waters eroded a large south-southeast oriented through valley linking the Platte River valley in the north with south-southeast oriented Wahoo Creek tributaries. This through valley parallels the adjacent south-southeast oriented Platte River valley and is now drained to the Platte River by Wahoo Creek. Headward erosion of the Wahoo Creek headwaters and tributary valleys was limited in the west by what was a deep south-southeast oriented flood flow channel, which is today the north-northwest oriented Skull Creek and south-southeast oriented Hunters Slough (and Oak Creek) through valley. Flood flow in the large south-southeast oriented Wahoo Creek drained through valley continued after headward erosion of the Platte River valley beheaded flood flow to western Wahoo Creek tributary valleys.

Preface:

• The purpose of this essay is to use topographic map interpretation methods to explore Platte River-Wahoo Creek drainage divide area landform origins in Saunders County, 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 Platte River-Wahoo Creek drainage divide area landform origins in Saunders County, Nebraska will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm. This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Platte River-Wahoo Creek drainage divide area location map

Figure 1: Platte River-Wahoo Creek drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.

Figure 1 provides a Platte River-Wahoo Creek drainage divide area location map. Nebraska is the state located in the figure 1 west half. Iowa occupies most of the figure 1 east half with Missouri located in the figure 1 southeast corner. The Missouri River flows in a south-southeast direction from the figure 1 north center edge along the Nebraska eastern border to the figure 1 south edge. The Platte River is located in Nebraska and flows in a northeast direction from Kearney (north of the figure 1 southwest corner near the west edge) to Columbus and North Bend. At North Bend the Platte River begins to change its direction to flow in an east-southeast direction to Fremont and to flow in an almost straight south direction to near Ashland. Near Ashland the Platte River changes direction again to flow in an east-northeast direction to join the south-southeast oriented Missouri River. Wahoo Creek is shown on figure 1, but is not labeled. It is the stream originating near Prague, Nebraska (just south of North Bend) and flowing in a southeast direction through Wahoo to join the Platte River near Ashland. Wahoo Creek tributaries originate along the Platte River valley edge north of Prague and there is a large northwest-southeast oriented valley extending from that region to the east-oriented Platte River valley near Ashland. Essays addressing drainage divides north and west of the Platte River-Wahoo Creek drainage divide area and can be found under Elkhorn River and Loup River on the sidebar category list. The hundreds of Missouri River drainage basin landform origins research project essays published on this website present a very strong case for massive southeast-oriented floods moving into and across Nebraska. Flood waters were probably derived from a rapidly melting thick North American ice sheet and were captured by headward erosion of the Platte River valley. Prior to Platte River valley headward erosion flood waters continued in a southeast direction across southeast Nebraska. Valleys in the Platte River-Wahoo Creek drainage divide area were eroded at the time the Platte River valley eroded west, north, and west from what was then a newly eroded and deep Missouri River valley. The Wahoo Creek valley and tributary valleys eroded headward first and the Platte River valley then beheaded southeast-oriented flood flow routes that had been eroding the Wahoo Creek drainage basin.

Platte River-Wahoo Creek drainage divide area detailed location map

Figure 2 provides a somewhat more detailed location map for the Platte River-Wahoo Creek drainage divide area. Butler, Saunders, Douglas, Sarpy, Seward, and Cass are Nebraska county names and the county boundaries are shown. The Platte River-Wahoo Creek drainage divide area illustrated and discussed here is almost entirely located in Saunders County. The Platte River forms the Saunders County north and east border. Wahoo Creek originates near Touhy in southwest Saunders County and flows in a northeast direction to the town of Wahoo and then turns to flow in a southeast direction to join the Platte River near the Saunders County southeast corner. Two Wahoo Creek tributaries originate in northern Saunders County almost along the edge of the Platte River valley. Sand Creek originates near Linwood in northeast Butler County, but has a tributaries that originate near Morse Bluff in northwest Saunders County and flows in a southeast and south direction to join Wahoo Creek near Wahoo. Silver Creek originates near Cedar Bluffs in northern Saunders County and flows in a south-southeast direction to join Wahoo Creek near Ithaca. Another Wahoo Creek tributary, Clear Creek, originates northwest of Yutan in east central Saunders County and after flowing to Yutan flows in a south direction (parallel to the nearby Platte River) to join Wahoo Creek near Ashland. West of the Wahoo Creek drainage basin along the Butler County east margin is north-northwest and north oriented Skull Creek, which flows on the same alignment as south-southeast oriented North Oak Creek in the Saunders County southwest corner. North Oak Creek flows in south-southeast direction to join northeast-oriented Salt Creek just south of the figure 2 south edge (the city located along the figure 2 south edge near that location is Lincoln). Salt Creek flows in a northeast direction to join Wahoo Creek near Ashland, just before Wahoo Creek flows to the Platte River (Wahoo Creek-Salt Creek and Platte River-Salt Creek drainage divides is addressed in a different essay found under Platte River on the sidebar category list). Note how Wahoo Creek flows to the Platte River near where the Platte River changes from being a south oriented river to being a northeast oriented river. The Wahoo Creek valley eroded northwest from what was then the actively eroding east and northeast oriented Platte River valley to capture south-southeast-oriented flood flow routes while the Platte River valley (and parallel south oriented Elkhorn River valley to the east) eroded in a north-northwest direction along major south-southeast oriented flood flow routes (probably flood water that had flowed south from an immense ice-walled and bedrock-floored valley carved into the rapidly melting ice sheet’s surface and located where the present day North and South Dakota James River valley is now located). For a time massive southeast-oriented floods moved along the southeast-oriented Wahoo Creek valley alignment. However, headward erosion of the Platte River valley turned to erode in a west direction across the southeast-oriented flood flow routes to behead all flood flow to the what was then the actively eroding Wahoo Creek drainage basin.

North end of Platte River-Wahoo Creek drainage divide area

Figure 3: North end of Platte River-Wahoo Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 uses reduced size maps to illustrate the large south-southeast oriented lowland linking the east oriented Platte River valley in the north with the southeast-oriented Wahoo Creek drainage basin, which drains to the east and northeast oriented Platte River valley in the south. In figure 3 Fremont is the city located in the northeast quadrant near the north edge. The Platte River flows in an east direction along the figure 3 north edge to Fremont and then turns to flow in a south-southeast direction to the figure 3 southeast corner. Wahoo is the town located in the figure 3 south center area. Wahoo Creek flows in a northeast and east-northeast direction to Wahoo and then turns to flow in a southeast direction to the figure 3 south center edge. The south-southeast oriented Wahoo Creek tributary joining Wahoo Creek at Wahoo is Sand Creek, which originates in the figure 3 northwest quadrant near the Platte River valley edge. Cedar Bluffs is the smaller town located north of Wahoo and just south of the Platte River. Silver Creek is the south-oriented Wahoo Creek tributary originating  along the Platte River valley edge north of Cedar Bluffs and flowing to join Wahoo Creek near Ithaca, an even smaller town located along the figure 3 south center edge. Note how Sand Creek and Silver Creek north of Wahoo flow on the floor of a large south-southeast oriented lowland or through valley, which roughly parallels the adjacent south-southeast oriented Platte River valley. Figure 3a below shows the south end of that large south-southeast oriented through valley where it joins with the Platte River near where the Platte River valley turns to flow in a northeast direction. Omaha is the city in the figure 3a northeast corner and Wahoo is the town located in the figure 3a northwest corner area. Wahoo Creek is the southeast-oriented stream flowing from Wahoo to join the Platte River. Ashland is the town located just west of where Wahoo Creek joins the Platte River. The large south-southeast oriented Wahoo Creek drained through valley originated as one of at least two large channels in a flood eroded south-southeast oriented anastomosing channel complex. The other large channel was the adjacent south-southeast oriented Platte River valley. When formed south-southeast oriented flood water was flowing in both of the large channels, although headward erosion of a deeper Platte River valley channel subsequently beheaded all south-southeast oriented flood flow to what is today the Wahoo Creek drained through valley.

Figure 3a: South end of the Wahoo Creek valley, where Wahoo Creek joins the Platte River. United States Geological Survey map digitally presented using National Geographic Society TOPO software.  

Platte River-Silver Creek drainage divide area

Figure 4: Platte River-Silver Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 provides a detailed map of the Platte River-Silver Creek drainage divide area north of Cedar Bluffs. The Platte River flows east along the figure 4 north edge and turns to flow in a south-southeast direction in the figure 4 northeast corner area. Silver Creek originates in section 7 (north of Cedar Bluffs) and flows in a south-southeast direction to the figure 4 south center edge. Silver Creek in the figure 4 map area is flowing along the east wall of the large south-southeast oriented through valley seen in figure 3. The east valley wall is approximately 80 feet high in this region. Note how the east-oriented Platte River valley has eroded across the north end of the shallow south-southeast oriented Silver Creek valley, which has been eroded into the floor of the east margin of the larger and slightly higher large south-southeast oriented through valley. As previously mentioned the large south-southeast oriented through valley originated as one of at least two large and adjacent south-southeast oriented flood flow channels. The Silver Creek valley probably originated as a slightly deeper channel within the larger south-southeast oriented channel, suggesting it was the location of a major flood flow route. The other adjacent large south-southeast oriented flood flow channel was the Platte River valley located east of the figure 4 map area. The channels were probably anastomosing and headward erosion of a deeper Platte River channel beheaded the south-southeast oriented flood flow routes to the Silver Creek channel. Beheading of flood flow to the Silver Creek valley did not result in a reversal of flood flow on the north end of the large south-southeast oriented through valley. Absence of evidence for significant flood flow reversal is interesting and suggests the beheading may have occurred while large amounts of water were flowing in both channels. Then as flood flow diminished flood waters spilling over into Wahoo Creek drained through valley simply became shallower and shallower until all flow could be contained in the Platte River valley . However it happened headward erosion of the Platte River valley beheaded the south-southeast oriented Silver Creek valley. Also note in section 25 headwaters of south- and southeast-oriented Elm Creek (not labeled in figure 4), which flows to the figure 4 east center edge. Note how a shallow through valley in the figure 25 northeast corner links the Elm Creek headwaters with headwaters of a short north-oriented Platte River tributary. That through valley provides evidence of another higher level and smaller south-southeast oriented flood flow channel. Headward erosion of the Platte River valley beheaded south-oriented flood flow to the actively eroding Elm Creek channel and flood waters on the north end of the beheaded flood flow channel reversed flow direction to erode the north-oriented Platte River tributary valley.

Platte River-Sand Creek drainage divide area

Figure 5: Platte River-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 illustrates the Platte River-Sand Creek drainage divide east of Linwood and west of the figure 4 map area and west of the large south-southeast oriented through valley (figure 5a below uses reduced size maps to illustrate the Sand Creek valley as it drains east to the large south-southeast through valley to the east). The east-northeast oriented Platte River valley is located in the north of the figure 5 map area and Linwood is the town located near the figure 5 west edge. Sand Creek is the east-southeast oriented stream originating in section 6 and flowing to the figure 5 southeast corner. A close look at drainage divides in figure 5 reveals numerous shallow through valleys linking the south-southeast oriented Sand Creek valley with valleys of north-oriented Platte River tributaries. For example, in section 32 headwaters of a south- and southeast-oriented Sand Creek tributary are linked by a through valley to headwaters of a north-oriented Platte River tributary. Also in the section 31 southeast corner a through valley links a short southeast-oriented tributary valley with headwaters of a short northwest-oriented tributary to a longer northeast-oriented Platte River tributary in sections 31 and 29. Dozens of such shallow through valleys can be seen in the figure 5 map area and these shallow through valleys provide evidence of south-oriented flood flow channels that existed prior to headward erosion of the large east-northeast oriented Platte River valley. Headward erosion of the east-southeast oriented Sand Creek valley and its tributary valleys occurred first. Through valleys linking the present day Platte River valley with the Sand Creek valley were eroded by south-oriented flood flow moving to what was then the newly eroded Sand Creek valley. Headward erosion of the Platte River valley next beheaded those south-oriented flood flow routes to the Sand Creek valley in sequence from east to west. North-oriented Platte River tributary valleys were eroded by reversals of flood flow on the north ends of the beheaded flood flow routes. The northeast-oriented Platte River tributary in sections 31 and 29 eroded headward just prior to headward erosion of the Platte River valley. Note multiple north-south oriented through valleys between the northeast-oriented Platte River valley in sections 31 and 29 and the Platte River valley. Figure 5a below illustrates the west wall of the large south-southeast oriented Wahoo Creek drained through valley seen in figure 3. Morse Bluff is the town located in the figure 5a northeast quadrant near the through valley’s west wall. Note evidence for flood flow reversal is much better west of the large through valley head area than it is at the through valley head. Again this suggests flood flow was great enough that it continued to spill into the large south-southeast oriented through valley after headward erosion of a deeper east-oriented Platte River channel had occurred. Flow in the through valley diminished as flood flow ended and Platte River flow levels dropped.

Figure 5a: Platte River-Sand Creek drainage divide area between figure 5 map area and west wall of the large south-southeast oriented Wahoo Creek drained through valley. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Elm Creek-Otoe Creek drainage divide area

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

Figure 6 illustrates the Elm Creek-Otoe Creek drainage divide area south and east of the figure 4 map area and includes overlap areas with figure 4. Cedar Bluffs is located just west of the figure 6 northwest corner and Fremont is located just to the northeast of the figure 6 northeast corner. Silver Creek flows in a south-southeast direction from the figure 6 northwest corner to the figure 6 south edge. The southeast-oriented Platte River is located in the figure 6 northeast corner. Elm Creek flows in a southeast direction in sections 33 and 34 to join the Platte River in the figure 6 northeast corner area. Otoe Creek originates in section 4 (in the figure 6 northeast quadrant south of Elm Creek) and flows through section 9 into section 16 where it turns to flow in southeast direction to the figure 6 south edge. Note shallow north-south oriented through valleys linking south-oriented Otoe Creek headwaters with headwaters of north-oriented Elm Creek tributary valleys. The through valleys are evidence of a south-oriented flood flow channel that existed prior to headward erosion of the Elm Creek valley. Flood waters were flowing south in those channels to what was then the actively eroding Otoe Creek valley. Headward erosion of the Elm Creek valley beheaded south-oriented flood flow to the Otoe Creek valley and as seen in figure 4 headward erosion of the Platte River valley beheaded south-oriented flood flow to what was then the actively eroding Elm Creek valley. Initially flood waters were flowing south across the entire figure 6 map area on a topographic surface at least as high as the highest figure 6 elevations today. Headward erosion of the Otoe Creek valley entered the figure 6 map area first and headward erosion of the Silver Creek valley probably was second. Headward erosion of the Platte River valley-Elm Creek valley next beheaded south-oriented flood flow to the Otoe Creek valley. As seen in figure 4 headward erosion of the Platte River valley next beheaded south-oriented flood flow to what was the actively eroding Elm Creek valley and subsequently to the Silver Creek valley. North-oriented Elm Creek tributary valleys were eroded by reversals of flood flow on the north ends of beheaded south-oriented flood flow routes. Remember the Elm Creek valley (and the Platte River valley) beheaded south-oriented flood flow channels one channel at a time (from east to west). Also remember the channels were anastomosing (or interconnected), meaning reversed flood flow in a newly beheaded channel could capture yet to be beheaded flood flow from adjacent channels. Such captures of yet to be beheaded flood flow helped erode the north-oriented tributary valleys.

Otoe Creek-Upper Clear Creek drainage divide area

Figure 7: Otoe Creek-Upper Clear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 7 illustrates the Otoe Creek-Upper Clear Creek drainage divide area south and east of the figure 6 map area. The south-southeast oriented Platte River valley is located in the figure 7 east third. Leshara is the town located in the figure 7 northeast quadrant. Otoe Creek is the stream flowing in a southeast direction from the figure 7 northwest corner and then turning to flow in a northeast and east direction to join the Platte River near Leshara. Upper Clear Creek is the southeast-oriented stream in the figure 7 southwest quadrant, which turns to flow in an east-northeast and then southeast direction in the figure 7 south center area. Note how there is a fairly significant north-south oriented through valley where sections 31, 32, 5, and 6 share a common corner near the figure 7 center. North-oriented Otoe Creek tributaries drain the through valley’s north end while a south-oriented Upper Clear Creek tributary drains the through valley’s south end. The through valley is evidence of a significant south-oriented flood flow channel that moved flood waters south to what was then an actively eroding Upper Clear Creek valley. Headward erosion of the east-oriented Otoe Creek valley beheaded that south-oriented flood flow channel and diverted flood waters east to what was then the newly eroded Platte River valley. Flood waters on the north end of the beheaded flood flow route reversed flow direction and eroded the north-oriented Otoe Creek tributary valley. Study of drainage divides between north-oriented Otoe Creek tributary valleys reveals shallow through valleys crossing those drainage divides. Those shallow through valleys provide evidence of routes used by yet to be beheaded south-oriented flood water used to reach reversed flood flow in newly beheaded flood flow channels and supports the interpretation that a deep Otoe Creek valley eroded headward across multiple south-oriented flood flow routes. Those flood flow channels had been eroded into a topographic surface at least as high as the highest figure 7 elevations today. In other words, the figure 7 map area was eroded by south-oriented flood water as the deep Platte River valley and its tributary valleys eroded headward into the region. The Upper Clear Creek valley probably reached the figure 6 map area first with the Platte River valley and its Otoe Creek tributary valley eroding headward into the region next.

Silver Creek-Clear Creek drainage divide area

Figure 8: Silver Creek-Clear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 uses reduced size maps to illustrate the Silver Creek-Clear Creek drainage area south of the figure 7 map area and includes overlap areas with figure 7 (in the figure 8 northeast quadrant). The south-southeast oriented Platte River valley is located in the figure 8 northeast corner area. Silver Creek flows south just east of the figure 8 west edge. The large southeast-oriented Wahoo Creek through valley is located in the figure 8 west half and the east valley wall extends in a northwest-southeast direction from the figure 8 north edge to the figure 8 south edge. Mead is the town located in the southeast-oriented Wahoo Creek drained through valley. Clear Creek is the east-northeast and southeast oriented stream originating east of Mead in a relatively narrow northeast to southeast oriented through valley used by the Union Pacific rail line between Mead and Yutan. Yutan is the town located near the figure 8 east edge. Upper Clear Creek flows in a southeast and east-northeast direction in the figure 8 north center area and then turns to flow in a southeast and south direction to join Clear Creek near Yutan. From Yutan Clear Creek flows in a southeast direction to the figure 8 southeast corner. Note how Clear Creek originates in the narrower northeast and southeast oriented through valley linking the large southeast Wahoo Creek drained through valley in the west with the south-southeast-oriented Platte River valley in the east. The Clear Creek through valley, and other through valleys in the figure 8 map area, provide evidence that water may have flowed between the south-southeast oriented through valley in the west and the Platte River valley in the east, although south-oriented flood flow from the north probably initiated headward erosion two separate valleys. One valley was a southeast-oriented valley from the newly eroded Platte River valley wall and the other was a southwest-oriented valley from the newly eroded southeast-oriented Wahoo Creek drained through valley east wall. These two valleys probably met west of Yutan and increased flood flow enabled the southeast-oriented Clear Creek valley head to erode headward into the southwest-oriented valley. At the time the Clear Creek and Upper Clear Creek valleys were eroded headward erosion of the deep Platte River valley had not yet reached the figure 4, 6, and 7 map areas and had not yet beheaded south-oriented flood flow to the Clear Creek drainage basin.

Skull Creek-Wahoo Creek drainage divide area

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

Figure 9 uses reduced size maps to illustrate the Skull Creek- Wahoo Creek drainage divide area west of the figure 3 map area and includes significant overlap areas with figure 3. Wahoo is the town located in the figure 9 southeast corner. Weston is the smaller town located near the figure 9 south edge and west of Wahoo. Wahoo Creek flows from Weston to Wahoo and then turns to flow in a southeast direction to the figure 9 southeast corner and eventually to reach the Platte River. Sand Creek is the south-southeast and south oriented Wahoo Creek tributary flowing from the figure 9 north edge to join Wahoo Creek at Wahoo. The west wall of the large south-southeast oriented through valley seen in figure 3 is located just west of Sand Creek. Cottonwood Creek is the southeast-oriented stream flowing from the figure 9 northwest quadrant through the small towns of Prague and Malmo to join Wahoo Creek at Wahoo (a railroad line follows the Cottonwood Creek valley from Prague to Wahoo). The North Fork Wahoo Creek is located between Cottonwood Creek and the figure 9 south edge and flows in a northeast direction before turning to flow in a southeast direction to join Wahoo Creek near Weston. West of the Cottonwood Creek headwaters near the figure 9 west edge is north-northwest oriented Skull Creek, which is flowing in a north-northwest to south-southeast oriented through valley. Near the figure 9 south edge that through valley is drained by south-southeast oriented Hunters Slough, which flows to south-southeast oriented Oak Creek. Oak Creek flows in a south-southeast oriented direction to Lincoln, where it joins Salt Creek, which flows in a northeast direction to join Wahoo Creek near Ashland. A north-northwest oriented Salt Creek tributary also joins Salt Creek at Lincoln and provides evidence the north-northwest oriented Skull Creek valley is located on the alignment of what was once a major south-southeast oriented flood flow channel. The flood flow in that south-southeast oriented flood flow channel was captured first by headward erosion of the northeast oriented Salt Creek valley and then was beheaded by headward erosion of the Platte River valley. After being beheaded by headward erosion of the Platte River valley flood waters on the north end of the south-southeast oriented flood flow channel reversed flow direction to create the north-northwest oriented Skull Creek valley and the Skull Creek-Hunters Slough drainage divide. Figure 10 below provides a more detailed map of the Skull Creek-Hunters Slough drainage divide area. North-south oriented through valleys link all northeast, east and southeast oriented Wahoo Creek tributary valleys. The through valleys are best seen on more detailed maps and figure 9a below illustrates the Cottonwood Creek-North Branch Wahoo Creek drainage divide in more detail. Note the through valley linking the north-northwest oriented Cottonwood Creek tributary in section 22 with the south-southeast North Fork Wahoo Creek tributary in section 27. Other north-south oriented through valleys can be seen further west along the drainage divide.

Figure 9a: Cottonwood Creek-North Fork Wahoo Creek drainage divide area near Malmo. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Detailed map of Skull Creek-Hunters Slough drainage divide area

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

Figure 10 provides a detailed map of the Skull Creek-Hunters Slough through valley seen in less detail in figure 9 above. Skull Creek is the north-northwest oriented stream flowing to the figure 10 northwest corner and is located in a north-northwest oriented through valley drained in the figure 10 southwest quadrant by south-southeast oriented Hunter’s Slough. East-oriented drainage east of the Skull Creek-Hunters Slough through valley flows to the North Fork Wahoo Creek. Note the many north-south and northwest-southeast oriented through valleys linking the deeper east-oriented valleys. As previously mentioned Hunters Slough continues to flow in a south-southeast direction to join south-southeast oriented Oak Creek. Oak Creek then flows in a south-southeast direction to near Lincoln where it joins northeast-oriented Salt Creek (see figure 2). A north-northwest oriented tributary joins Salt Creek opposite the south-southeast oriented Oak Creek valley and provides evidence the through valley continues further to the south-southeast. The through valley probably was initiated as a major south-southeast oriented flood flow channel prior to headward erosion of the Salt Creek and Platte River valleys. Headward erosion of the northeast-oriented Salt Creek valley first captured the south-southeast oriented floods flow route. Flood waters on the north-northwest end of the beheaded flood flow reversed flow direction to flow in a north-northwest direction to the newly eroded and deeper northeast-oriented Salt Creek valley and eroded present day north-northwest oriented Salt Creek tributary valleys. Apparently south-southeast flood flow in this Skull Creek-Hunters Slough (Oak Creek) through valley (flood flow channel) was able to then erode the channel floor deep enough that headward erosion of the Wahoo Creek tributary valleys were not able to capture south-southeast oriented flood flow and for that reason Wahoo Creek tributary valleys eroded headward almost to the south-southeast oriented valley wall, but did not intersect and capture the south-southeast oriented flood flow channel. Headward erosion of the Platte River valley in the north next captured the south-southeast oriented flood flow. Flood waters on the north-northwest end of the beheaded flood flow channel reversed flow direction to flow in a north-northwest direction to newly eroded and deeper Platte River valley and to create the Skull Creek-Hunters Slough drainage divide.

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.