Platte River-Big Blue River drainage divide area landform origins in Hamilton, Polk, Butler, York, and Seward Counties, Nebraska, USA

· Big Blue River, Nebraska, Platte River (NE)
Authors

A geomorphic history based on topographic map evidence

Abstract:

The Platte River-Big Blue River drainage divide area in Hamilton, Polk, Butler, York, and Seward Counties was eroded by a massive east oriented flood, which was first captured by headward erosion of the south-southeast oriented Big Blue River and later captured by headward erosion of the deeper northeast and east oriented Platte River valley. Flood waters were probably derived from a rapidly melting thick North American ice sheet and entered Nebraska from the north, northwest, and west and were moving east and southeast to what was then the newly eroded and actively eroding Missouri River valley. The south-southeast oriented Big Blue River valley eroded headward from the newly eroded Kansas River valley to capture east and southeast oriented flood water. The south-southeast oriented Platte River valley (between Fremont and Ashland) also eroded headward from the newly eroded Missouri River valley to capture east oriented flood water. Headward erosion of the large Platte River valley west and southwest from Fremont eroded a slightly deeper flood flow channel and beheaded all east-oriented flood flow to newly eroded Big Blue River valley.

Preface:

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.                    

Introduction:

  • The purpose of this essay is to use topographic map interpretation methods to explore Platte River-Big Blue River drainage divide area landform origins in Hamilton, Polk, Butler, York, and Seward Counties, 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 River-Big Blue River drainage divide area landform origins in Hamilton, Polk, Butler, York, and Seward Counties, 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-Big Blue River drainage divide area location map

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

Figure 1 provides a Platte River-Big Blue River drainage divide area location map and illustrates a region in eastern Nebraska. The Missouri River flows in a south-southeast direction near the figure 1 east edge and is the Nebraska-Iowa border. Iowa is located east of Missouri River and Nebraska is west of the Missouri River. The Platte River flows in a northeast direction from Kearney (located just west of the figure 1 west edge) to Grand Island, Central City, Columbus and North Bend. At North Bend the Platte River begins to turn in a southeast direction to flow to Fremont and then in a south-southeast direction to flow to Ashland. Near Ashland the Platte River turns to flow in an east-northeast direction to join the Missouri River near Plattsmouth. The Big Blue River originates near Marquette (south of Central City) and flows in a northeast  and east-southeast direction to Ulysses where it joins south-oriented North Branch and then flows in a south-southeast direction to Seward, Crete, Beatrice, and the figure 1 south edge. South of figure 1 the Big Blue River flows into Kansas and joins the east-oriented Kansas River, which flows to the Missouri River at Kansas City. Lincoln Creek is an east-oriented Big Blue River tributary, which originates southeast of Grand Island, and which joins the south-southeast oriented Big Blue River near Seward. This essay addresses landform evidence in the region between the northeast-oriented Platte River extending from Grand Island to about Schuyler and the east oriented Lincoln Creek channel and also between the south-southeast oriented Big Blue River north of Seward and south-southeast oriented Oak Creek (the unlabeled stream north of Lincoln which flows south-southeast through Valparaiso). Note the presence of numerous southeast-oriented drainage routes along the figure 1 north edge area and also in the figure 1 southeast quadrant. Big Blue River tributaries in the figure 1 southwest quadrant are east-oriented, but flow to the south-southeast oriented Big Blue River. Other essays have illustrated and discussed landform evidence in the Loup River drainage basin north of the Platte River (see Loup River on sidebar category list) and also in the Platte River-Salt Creek drainage divide area, Platte River-Wahoo Creek drainage divide area, Platte River-Missouri River drainage area (see Platte River on sidebar category list), and Little Nemaha River-Big Nemaha River drainage divide area (see NE Missouri River on sidebar category list) all located between the south-southeast oriented Big Blue River and the Missouri River. These and hundreds of other Missouri River drainage basin landform origins research project essays published on this website present overwhelming evidence for a massive southeast or south-southeast oriented floods, which originated with a rapidly melting thick North American ice sheet and which flowed across Nebraska as the Platte River valley eroded headward across Nebraska to capture southeast-oriented flood waters and to divert flood waters to what was then the newly eroded Missouri River valley. Missouri River drainage basin landforms origins research project essays have also presented evidence for massive east-oriented floods entering western Nebraska and being captured by Platte River valley headward erosion.

Platte River-Big Blue River drainage divide area detailed location map

Figure 2: Platte River-Big Blue 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 Platte River-Big Blue River drainage divide area. Nance, Platte, Colfax, Dodge, Merrick, Polk, Butler, Saunders, Hamilton, York, Seward, and Lancaster are Nebraska county names and the county boundaries are shown. Lincoln is the city located in the figure 2 southeast corner area and Grand Island is the city located along the figure 2 west edge in the figure 2 southwest corner area (the name does not show in figure 2). The Platte River flows in a northeast direction from the figure 2 southwest corner to Columbus in southeast Platte County and then flows in an east direction to Fremont along the figure 2 east edge. North of the Platte River is the northeast-oriented Loup River, which joins the Platte River near Columbus. The Loup River and Platte River channels are located on opposites sides of the same large northeast-oriented valley and the Loup River-Platte River drainage divide area between Kearney and Columbus essay illustrates and describes that valley. The northwest wall of that large northeast-oriented Loup River-Platte River valley is much better defined than the southeast wall, which forms the Platte River-Big Blue River drainage divide area. The Big Blue River originates in northern Hamilton County (near Marquette and north of Aurora) and flows in a generally northeast direction into southern Polk County. In Polk County the Big Blue River turns to flow in an east-southeast direction to Ulysses in south central Butler County. At Ulysses the south-oriented North Branch joins the Big Blue River and the Big Blue River flows in a south-southeast direction to Seward and then to the figure 2 south edge. South of the east-oriented Big Blue River is east-oriented Lincoln Creek, which originates near Phillips, almost on the Platte River banks in western Hamilton County. Lincoln Creek flows in a generally east direction across Hamilton County and York County and then joins the south-southeast oriented Big Blue River at Seward in Seward County. East of the south-southeast oriented Big Blue River in Butler and Seward Counties is south-oriented Plum Creek, which joins the Big Blue River at Seward. East of Plum Creek is south-southeast oriented Oak Creek, which flows to northeast-oriented Salt Creek at Lincoln. Salt Creek flows in a northeast direction from Lincoln to join the Platte River, which has turned sharply to flow south before turning to flow east to the Missouri River. North of Oak Creek in Butler County, although on the same alignment, is north-northwest oriented Bone Creek, which then turns to flow in a north-northeast direction to join the Platte River. As already mentioned this essay focuses on the region between the northeast-oriented Platte River valley, the east oriented Lincoln Creek valley and the north-northwest oriented Bone Creek valley and south-southeast oriented Oak Creek valley.

Platte River-Lincoln Creek drainage divide area in Hamilton County

Figure 3: Platte River-Lincoln Creek drainage divide area in Hamilton County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Platte River-Lincoln Creek drainage divide area in Hamilton County and also the Big Blue River and Lincoln Creek headwaters areas. The Platte River is the northeast-oriented river in the figure 3 northwest quadrant and is flowing along the southeast wall of the large Loup River-Platte River valley. The northeast-oriented Loup River channel is located along the valley’s northwest wall, which is located a considerable distance to the northwest of the figure 3 northwest corner (see Loup River-Platte River drainage divide area between Kearney and Columbus essay). Aurora is the town located near the figure 3 south center edge and Marquette is located in the figure 3 north center area almost directly north of Aurora. Figure 3a below illustrates the Lincoln Creek headwaters area west and south of the figure 3 map area and includes overlap areas with figure 3. Lincoln Creek is located in the figure 3 south half and flows northeast, east, and then southeast to Aurora. From Aurora Lincoln Creek flows in a northeast and east direction to the figure 3 east edge. North of Lincoln in the figure 3 west center area are Big Blue River headwaters and after several significant jogs both to north and to the south the Big Blue River south of Marquette turns to flow in a northeast direction to the figure 3 northeast corner. What is particularly interesting about the Platte River-Big Blue River (and Lincoln Creek) drainage divide area in figures 3 and 3a is the “east”-oriented Big Blue River and Lincoln Creek headwaters are located almost on the edge of large northeast-oriented Platte River valley. Further, the Platte River valley wall is very low, as little as 20-30 meters, and much lower than the northwest valley wall (located northwest of the northeast-oriented Loup River channel). What has happened here is the northeast-oriented Platte River (and Loup River) valley has eroded headward across what was a major east-oriented flood. The east-oriented flood was moving to what was then the newly eroded south-southeast oriented Big Blue River valley in Butler and Seward Counties (and also further to the south), which had eroded headward from the newly eroded east-oriented Missouri River-Kansas River valley in Missouri and Kansas. The Platte River valley was eroding west and southwest from what was then the newly eroded south-southeast oriented Missouri River valley (in eastern Nebraska), which had eroded headward from the newly eroded east-oriented Missouri River-Kansas River valley to the south. Headward erosion of the Platte River valley was capturing southeast-oriented flood flow from the northwest and in this figure 3 and 3a map area encountered and captured a major east-oriented flood as well. The east-oriented flood was coming from west of Nebraska while the southeast-oriented flood was coming from north and northwest of Nebraska.
Figure 3a: Lincoln Creek headwaters area west and south of the figure 3 map area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Platte River-Big Blue River drainage divide area in Polk County

Figure 4: Platte River-Big Blue River drainage divide area in Polk County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the Platte River-Big Blue River drainage divide area in Polk County and is located east and north of the figure 3 map area. Osceola is the town in the figure 4 northeast quadrant. Stromsburg is the town located southwest of Osceola. Polk is the smaller town located in the figure 4 southwest quadrant and Clarks is the small town in the figure 4 northwest corner. The Platte River flows in a northeast direction across the figure 4 northwest corner. The Big Blue River flows in a northeast direction from the figure 4 south edge (directly south of Polk) to the figure 4 east edge. Prairie Creek is the east-northeast oriented stream flowing from the figure 4 west edge to join the Big Blue River near Stromsburg. Prairie Creek, like the Big Blue River and Lincoln Creek, originates almost on the banks of the northeast oriented Platte River valley. Davis Creek is the northeast-oriented stream flowing to Osceola and then turning to flow in a south direction to join the Big Blue River near the figure 4 east edge. Clear Creek is the north oriented Platte River tributary in the figure 4 north center area. Southeast-oriented drainage in the figure 4 southeast corner flows to Lincoln Creek. Note the Platte River valley wall continues to be rather low (30-50 meters at the most). The large northeast oriented Platte River valley in this figure 4 region appears to be a slightly deeper channel eroded into the floor of a much larger northeast and east oriented flood flow channel, the south half of which drains to the south-southeast oriented Big Blue River, which flows to the Kansas River. In other words, the figure 4 map evidence like the figures 3 and 3a map evidence suggests an immense east and northeast oriented flood flowed across central and southern Nebraska in this region with headward erosion of the south-southeast oriented Big Blue River valley capturing the south half of the east and northeast oriented flood and the slightly deeper Platte River valley eroding headward along the northeast half of the flood in a southwest direction to behead east and northeast oriented flood flow to what was then the newly eroded south-southeast oriented Big Blue River valley. The east oriented Big Blue River and its east-oriented tributary valleys were eroded by final east and northeast oriented flood waters, just before the Platte River valley captured all flood flow.

Big Blue River-Lincoln Creek drainage divide area in northern York County

Figure 5: Big Blue River-Lincoln Creek drainage divide area in northern York County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Big Blue River-Lincoln Creek drainage divide area south of the figure 5 map area and includes overlap areas with figure 4. Polk is the town near the figure 5 northwest corner and the north edge. Benedict is the town in the figure 5 east center area. The Big Blue River flows from the figure 5 west edge (northwest corner area) in a an east and then northeast direction to the figure 5 north center edge. Lincoln Creek is located in the figure 5 south half and flows from the southwest corner in an east-northeast direction to the figure 5 south center and then turns to flow in a southeast direction before turning to flow in a northeast direction to the figure 5 east edge. Lincoln Creek has numerous south and southeast oriented tributaries. These tributaries to the Lincoln Creek valley were eroded prior to the Big Blue River valley headward erosion when flood waters could flow south into what was then the newly eroded Lincoln Creek valley. Headward erosion of south oriented tributary valleys continued until the Big Blue River valley beheaded the south-oriented flood flow. Probably headward erosion of the Lincoln Creek valley was only slightly in advance of Big Blue River valley headward erosion. Otherwise headward erosion of one or more of the south-oriented Lincoln Creek tributary valleys would have eroded far enough north to capture flood flow eroding the Big Blue River valley (the Lincoln Creek valley is slightly deeper than the Big Blue River valley to the north). The figure 5 landscape was eroded by southeast-oriented flood water being captured by headward erosion of east oriented Big Blue River tributary valleys (including the east oriented Big Blue River valley), which was diverting the southeast-oriented flood water to the newly eroded south-southeast oriented Big Blue River valley. Headward erosion of the deeper northeast oriented Platte River-Loup River valley to the north and west beheaded all south and southeast oriented flood flow routes to the figure 5 map area and remaining flood waters drained from the region. As remaining flood waters drained the valleys may have been deepened and/or extended.

Platte River-Big Blue River drainage divide area east of Osceola

Figure 6: Platte River-Big Blue River drainage divide area east of Osceola. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Platte River-Big Blue River drainage divide area east of Osceola and east of the figure 4 map area and includes overlap areas with figure 4. Osceola is the town located near the figure 6 west center edge. Shelby is the town located east of Osceola and Rising City is located east of Shelby. Millerton is the place-name near the figure 6 east center edge. The southeast wall of the northeast oriented Platte River valley is located in the figure 6 northwest corner. The Platte River is located in the valley north of the figure 6 map area. The Big Blue River flows in a northeast direction in the figure 6 southwest corner and then turns to flow in a southeast direction to the figure 6 south edge (east half). The south oriented stream along the figure 6 east center edge near Millerton and also in the figure 6 southeast corner is the south-oriented North Branch (Big Blue River), which joins the Big Blue River south of the figure 6 map area. East oriented drainage routes in the Shelby and Rising City areas flow to the south-oriented North Branch and then the south-southeast oriented Big Blue River. Note the shallow depth of the Platte River valley and how the Big Blue River drainage begins along the Platte River valley edge. Figure 6 evidence suggests the Platte River valley has eroded a deeper channel in what was a much larger northeast, east and southeast oriented flood flow channel. Flood waters in the southern half of that much larger flood flow channel were captured by headward erosion of the south-southeast oriented Big Blue River valley (and its south-oriented North Branch valley). Flood waters north of the south-southeast oriented Big Blue River valley (and south-oriented North Branch valley) were not captured and flowed east to where they were captured by headward erosion of the south-southeast oriented Platte River valley, which had eroded headward from the newly eroded Missouri River valley. The Platte River valley was able to erode a deeper channel headward in central Nebraska and that deeper channel gradually beheaded flood flow routes to what is now the Big Blue River drainage basin. Note the lack of any significant Platte River tributaries in figure 6. Absence of Platte River tributaries is evidence there were no massive flood flow reversals. Instead flood waters flowing across the Platte River-Big Blue River drainage divide simply decreased as the deeper Platte River valley captured the northeast, east, and southeast oriented flood flow.

Big Blue River-Lincoln Creek drainage divide area west of Ulysses

Figure 7: Big Blue River-Lincoln Creek drainage divide area west of Ulysses. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Big Blue River-Lincoln Creek drainage divide area west of Ulysses and south of the figure 6 map area and includes overlap areas with figure 6. Staplehurst is the town in the figure 7 southeast corner. The south-southeast oriented Big Blue River flows through Staplehurst and Ulysses is the town along the Big Blue River north of Staplehurst. North of Ulysses is the junction of the southeast oriented Big Blue River and the south-southwest oriented North Branch. Surprise is the small town located in the Big Blue River valley northwest from Ulysses. Lincoln Creek flows in a northeast, southeast, and east direction from the figure 7 southwest corner to the figure 7 southeast corner and joins the Big Blue River southeast of the figure 7 map area (see figure 10 below). Note southeast and south oriented tributaries to east oriented Lincoln Creek. The Lincoln Creek valley began to erode west from what was then the actively eroding south-southeast oriented Big Blue River valley head to capture southeast oriented flood water flowing across the figure 7 map area. At that time the Big Blue River valley to the north did not exist, nor did the Platte River valley further to the north exist. Headward erosion of the south-southeast oriented Big Blue River valley head to the Ulysses area permitted the southeast oriented Big Blue River valley to erode headward from that area along a southeast-oriented flood flow route, which beheaded southeast-oriented flood flow to what were then actively eroding southeast oriented Lincoln Creek tributary valleys. At the same time the south oriented North Branch valley eroded headward from Ulysses to capture east and southeast oriented flood flow north of the newly eroded southeast oriented Big Blue River valley. Headward erosion of the deeper Platte River flood flow channel to the north and northwest then beheaded all flood flow routes to the present day Big Blue River drainage basin.

Platte River-North Branch Big Blue River drainage divide area

Figure 8: Platte River-North Branch Big Blue River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Platte River-North Branch Big Blue River drainage divide area north of the figure 7 map area and east of the figure 6 map area and includes overlap areas with figure 6. Rising City is the town located in the figure 8 southwest quadrant. David City is the much larger town located in the northeast quadrant. Garrison is the smaller town located in the figure 8 south center. The north facing Platte River south valley wall is located along the figure 8 north edge (west half). The south oriented North Branch Big Blue River is located south of David City and south and southwest oriented Kezan Creek joins the North Branch near Garrison. Brainard is the small town located near the figure 8 east edge and in the southeast quadrant. The southeast oriented streams originating just east of Brainard are Middle and North Oak Creek. Oak Creek flows in a southeast direction to join northeast-oriented Salt Creek at Lincoln and then to flow to the Platte River at Ashland (see figures 2 and 1). The northwest-oriented stream in the figure 8 northeast quadrant is Bone Creek. Bone Creek originates in the figure 8 east center edge area. Note how northwest-oriented Bone Creek and southeast-oriented Oak Creek headwaters are on the same northwest-southeast alignment. That northwest-southeast alignment continues southeast of Lincoln (and the northeast-oriented Salt Creek valley) to the southeast-oriented Big Nemaha River valley (the unlabeled stream in figure 1 flowing through Tecumseh), which drains to the Missouri River near the Nebraska-Kansas state line. That northwest-southeast alignment probably originated with a major southeast-oriented flood flow channel that was subsequently dismembered by headward erosion of the Platte River-Salt Creek valley and then again by Platte River valley headward erosion. In the case of the Platte River valley headward erosion the Platte River captured the southeast-oriented flood flow, which beheaded the flood flow channel. Flood waters on the northwest end of the beheaded flood channel reversed flow direction to flow in a northwest direction to the newly eroded Platte River valley. In other words evidence for headward erosion of at least three different south-southeast oriented channels (or valleys) influenced flood waters in the figure 8 map area. The south and south-southeast oriented North Branch and Big Blue River valley eroded headward into figure 8 to capture east and southeast oriented flood water moving to the southeast oriented Bone Creek-Oak Creek channel. Headward erosion of the deeper south-southeast oriented Missouri River valley and its south-southeast oriented Platte River valley tributary (east of the figure 8 map area) enabled the deeper Platte River valley to erode west and southwest to behead the southeast-oriented Bone Creek-Oak Creek channel and later to behead flood flow routes to the Big Blue River.

Big Blue River-Oak Creek drainage divide area east of Ulysses

Figure 9: Big Blue River-Oak Creek drainage divide area east of Ulysses. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Big Blue River-Oak Creek drainage divide area east of Ulysses, east and south of the figure 7 map area, and includes overlap areas with figure 7. Ulysses is the town located near the figure 9 west edge. Dwight is the smaller town located in the figure 10 east center area. The southeast-oriented Big Blue River joins the south-oriented North Branch just north of Ulysses and the combined Big Blue River flows south from Ulysses to the figure 9 south edge. East of the Big Blue River in the figure 9 southwest quadrant is south-oriented Big Weedy Creek. East of Big Weedy Creek and just west of Dwight is south-southwest oriented Plum Creek, which flows from the figure 9 north edge to the figure 9 south center edge. Plum Creek originates near Brainard in the figure 8 southeast corner and joins the Big Blue River near Seward (see figure 10). East of Dwight and flowing to the figure 9 southeast corner is south-southeast and southeast oriented Oak Creek. The southeast-oriented stream located in the figure 9 northeast corner is Middle Oak Creek, which originated east of Brainard in figure 8 above. What has happened here is east-oriented flood flow was moving across the figure 9 map area, probably headed toward what was then the newly eroded Missouri River valley. The flood waters were flowing on a topographic surface higher than the surface that exists today. Headward erosion of the Big Nemaha River valley from the newly eroded Missouri River valley near the Nebraska southeast corner enabled southeast-oriented valleys to erode headward along the Oak Creek alignment. These southeast-oriented valleys captured the east-oriented flood waters and diverted the flood flow in a southeast direction to the actively eroding Big Nemaha River valley. At about the same time the Big Blue River valley was eroding headward into Nebraska, but had not yet reached the figure 9 map area. Next headward erosion of the Platte River valley west from the newly eroded Missouri River near Plattsmouth and of the northeast-oriented Salt Creek valley headward from the Platte River valley near Ashland captured southeast-oriented flood flow on the Oak Creek alignment and diverted the flood waters to the newly eroded Platte River valley near Ashland and eroded the Oak Creek drainage basin deeper than it had been earlier. Shortly thereafter headward erosion of the south-southeast oriented Big Blue River valley entered the figure 9 map area and captured much of the east-oriented flood water moving to the newly deepened Oak Creek drainage basin. Finally headward erosion of the Platte River valley north and west from the Ashland area beheaded all southeast-oriented flood flow routes from the north to the Middle and North Oak Creek valleys (causing a reversal of flood flow on the northwest end of the beheaded flood flow channel to create the northwest-oriented Bone Creek valley). Continued Platte River headward erosion then beheaded all east-oriented flood flow routes to the newly south-southeast oriented Big Blue River valley.

Big Blue River tributary drainage divides northwest of Seward

Figure 10: Big Blue River tributary drainage divides northwest of Seward. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates Big Blue River tributary drainage divides in the region immediately northwest from Seward, is located south of the figure 9 map area, and includes overlap areas with figure 9. Seward is the city located in the figure 10 southeast quadrant. The south-southeast oriented Big Blue River flows from the figure 10 north center area to Seward and then to the figure 10 south edge. Staplehurst is the smaller town located in the Big Blue River valley northwest from Seward. Lincoln Creek is the southeast-oriented tributary flowing from the figure 10 west edge to join the Big Blue River at Seward. Cottonwood Creek is the southeast-oriented Lincoln Creek tributary located in the figure 10 northwest corner. Bee is the even smaller town located in the figure 10 northeast corner area. The south-oriented immediately west of Bee is Plum Creek and the south-southeast Plum Creek tributary between Plum Creek and the Big Blue River is Big Weedy Creek. Plum Creek also joins the Big Blue River at Seward. What has happened here is the Big Blue River valley eroded headward into the Seward region to capture east and southeast oriented flood flow. At that time flood waters were flowing on a higher topographic surface than exists today and the Big Blue River valley was a deeper than appears today. Headward erosion of the Plum Creek valley first captured the east-oriented flood water, then headward erosion of the Big Weedy Creek valley captured the flood flow. Next, and very shortly after, Big Blue River valley headward erosion captured all flood flow to the actively eroding Big Weedy Creek valley and then to the Plum Creek valley. At the same time the Lincoln Creek valley was eroding northwest and west along a major east-oriented flood flow routes. North of the figure 10 and 9 map areas the Platte River valley was eroding westward and finally beheaded east-oriented flood flow routes to the actively eroding Big Blue River valley and then to the actively eroding Lincoln Creek valley. The valleys today have changed little since that time.

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.

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