A geomorphic history based on topographic map interpretation

The Platte River-Republican River drainage divide area in Gosper and Furnas Counties, Nebraska was eroded by massive south-oriented floods. Flood waters were probably derived from a rapidly melting thick North American ice sheet and initially flowed across Nebraska into Kansas to the south. Headward erosion of the east-oriented Republican River valley from what was then the newly eroded Kansas River valley captured south-oriented flood flow in what is now Furnas County. A constantly changing complex of anastomosing channels then moved flood waters south to the newly eroded Republican River valley as multiple deep and south-oriented tributary valleys eroded headward from the newly eroded Republican River valley north wall into what is now Gosper County and eastern Frontier County. Headward erosion of the Platte River valley from what was then the newly eroded Missouri River valley next entered the region just north of Gosper County. First the Plum Creek valley eroded headward (south-southwest, northwest, south, and northwest) from what was then the actively eroding Platte River valley head. Headward erosion of the Plum Creek valley beheaded all south-oriented flood flow to what were then the actively eroding south-oriented Republican River tributary valleys in present day Gosper County and eastern Frontier County. Platte River valley headward erosion closely followed and beheaded all south-oriented flood flow routes to the newly eroded Plum Creek valley. Deep valleys were eroded into a relatively level topographic surface, which was underlain by easily eroded material. The topographic surface may have been an erosion surface formed during earlier flood stages and/or may have been formed by deposition of flood transported sediments.

Preface:

• The purpose of this essay is to use topographic map interpretation methods to explore Platte River-Republican River drainage divide area landform origins in Gosper and Furnas 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-Republican River drainage divide area landform origins in Gosper and Furnas 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-Republican River drainage divide area location map

Figure 1 provides a Platte River-Republican River drainage divide area in Gosper and Furnas Counties, Nebraska location map. The west to east oriented boundary line is the Nebraska-Kansas state line, where Nebraska is in the north and Kansas is in the south. The Platte River flows in a southeast direction from North Platte, Nebraska (in the figure 1 northwest corner) to Kearney and then in a northeast direction to Grand Island and Central City before flowing the figure 1 northeast corner area. East of the figure 1 map area the Platte River flows to the south-southeast oriented Missouri River, which at Kansas City, Missouri turns to flow in an east direction to the south-oriented Mississippi River. The Republican River flows in an east and east-southeast direction from the figure 1 west edge to McCook, Nebraska (just north of the state line and near the west edge) to Holbrook, Arapahoe, Oxford, Alma, Republican City, Red Cloud, Guide Rock, and Superior, Nebraska before turning to flow in a south-southeast direction to Republic and Scandia, Kansas and the figure 1 southeast corner. South and east of the figure 1 map area the Republican River flows in a southeast direction to join the east-oriented Kansas River, which joins the Missouri River at Kansas City. This essay investigates drainage divide evidence in the region located between Lexington (on the Platte River) and Arapahoe (on the Republican River). North of the Republican River in the figure 1 east half is the southeast oriented Little Blue River, which east of the figure 1 map area flows to the south-southeast oriented Big Blue River. The Big Blue River is a Kansas River tributary. The Platte River-Little Blue River drainage divide area in Hall, Hamilton, Adams, and Clay Counties and the Little Blue River-Republican River drainage divide area in Kearney, Adams, Franklin, and Webster Counties essays address regions east of the drainage divide area investigated here and can be found under Big Blue, Platte River, or Republican River as appropriate for the divide area on the sidebar category list. Hundreds of Missouri River drainage basin research project essays published on this website provide significant evidence for massive south and southeast oriented floods which flowed across Nebraska and into Kansas. Flood waters were probably derived from a rapidly melting North American ice sheet. The Republican River valley eroded headward from what was then a newly eroded Kansas River valley to capture southeast and south oriented flood flow. Shortly thereafter the Platte River valley eroded headward from what was then the newly eroded Missouri River valley and beheaded all flood flow routes to the newly eroded Republican River valley.

Platte River-Republican River drainage divide area detailed location map

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

Figure 2 provides a somewhat more detailed location map for the Platte River-Republican River drainage divide area in Gosper and Furnas Counties, Nebraska. Frontier, Gosper, Phelps, Red Willow, Furnas, Harlan, and Franklin are Nebraska county names and county boundaries are shown. The Platte River flows in a southeast direction in the figure 2 north center edge area to serve as the Phelps and Kearney County northern border. The Republican River flows in an east-northeast direction from the figure 2 west edge through Red Willow County into northern Furnas County and then flows in a southeast direction to Harlan County Lake (a reservoir impounded behind a dam) and then in an east direction across Franklin County to the figure 2 east edge. Note the numerous and relatively long southeast and south oriented Republican River tributaries from the north, especially in eastern Frontier County, Gosper County, and western Phelps County. Major Platte River tributaries from the south are less numerous and generally do not extend far south from the Platte River channel. There are some northeast-oriented Platte River tributaries in Phelps and Kearney Counties, but further west the only Platte River tributary of significance is Plum Creek, which flows in a southeast direction (parallel to the Platte River) across the Frontier County northeast corner into northern Gosper County, where it makes a jog to the north before flowing in a southeast direction some more. Finally, south of Lexington and in northeast Gosper County, Plum Creek turns to flow in a northeast direction to join the Platte River. Numerous and closely spaced south oriented Republican River tributaries originate just south of southeast oriented Plum Creek and flow significant distances to join the east-oriented Republican River in northern Furnas County. Note north-oriented Republican River tributaries located along the figure 2 south edge. Note also southeast and south oriented tributaries north of the Platte River in the figure 2 northeast quadrant. What has happened here is prior to headward erosion of present day valleys massive south and southeast oriented flood flow moved across the entire figure 2 map area. The east-oriented and deep Republican River valley then eroded headward across the figure 2 map area to capture south-oriented flood flow. South oriented tributary valleys eroded north from the actively eroding Republican River valley head. At the same time flood waters on north ends of beheaded south oriented flood flow routes reversed flow direction to erode north oriented Republican River tributary valleys. Headward erosion of the Platte River valley (and semi parallel tributary valleys) next beheaded south oriented flood flow to the actively eroding south oriented Republican River tributary valleys. Topographic maps below illustrate evidence supporting this interpretation.

Platte River-Plum Creek drainage divide area

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

Figure 3 illustrates the Platte River-Plum Creek drainage divide area located in northwest Gosper County and adjacent Dawson and Frontier Counties. Elwood is the town located near the figure 3 south center edge. The southeast-oriented Platte River is located in a broad, but shallow southeast-oriented valley in the figure 3 northeast quadrant. Note short northwest-oriented tributary valleys in the figure 3 northwest quadrant. Those northwest-oriented tributary valleys were eroded by reversals of flood flow on northwest ends of southeast-oriented flood flow routes beheaded by Platte River valley headward erosion. Plum Creek flows in a southeast direction from the figure 3 west center edge and then turns to flow in a north direction before turning to flow in a southeast direction across the figure 3 center area. In the figure 3 southeast quadrant Plum Creek turns again to flow in a north-northeast direction to flow to the southeast-oriented Platte River valley. Headward erosion of the Plum Creek valley beheaded numerous south-oriented flood flow routes to what were then actively eroding south-oriented Republican River tributary valleys. Some of those south-oriented Republican River tributary valleys can be seen in the figure 3 southwest quadrant. Note north-oriented Plum Creek tributaries from the south. North-oriented Plum Creek tributary valleys were also eroded by reversals of flood flow on north ends of south-oriented flood flow routes beheaded by Plum Creek valley headward erosion. Southeast-oriented Plum Creek tributary valleys were eroded by southeast-oriented flood flow moving into what was then the newly eroded Plum Creek valley. At that time the Platte River valley to the north of the Plum Creek valley did not yet exist. The north-northeast oriented Plum Creek valley in the figure 3 southeast quadrant was probably eroded by reversed flood flow on north ends of south-oriented flood flow routes beheaded by what was then the actively eroding Platte River valley head. The southeast-oriented Plum Creek valley across the figure 3 center area was eroded headward across south-oriented flood flow to what were then actively eroding south-oriented Republican River tributary valleys. The north-oriented Plum Creek valley segment in the figure 3 west center area was probably eroded by a reversal of flood flow on the north end of a beheaded south-oriented flood flow route. The Plum Creek valley then continued to erode headward (or to the northwest) from the south end of that north-oriented valley segment. Figure 4 below provides a detailed map of the Plum Creek-Republican River drainage divide area seen in the figure 3 southwest quadrant.

Detailed map of Plum Creek-Republican River drainage divide area

Figure 4: Detailed map of Plum Creek-Republican River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed map of the Plum Creek-Republican River drainage divide area seen in less detail in the figure 3 southwest quadrant. Plum Creek is located near the figure 4 north edge and flows from the figure 4 north edge (west half) in a southeast direction to the figure 4 north center area and then turns to flow in a northeast direction to the figure 4 north edge (east half). North of the figure 4 map area Plum Creek flows in a north direction before resuming its southeast-oriented flow (see figure 3). South-oriented drainage in the figure 4 map area all flows to the east-oriented Republican River located south of the figure 4 map area. Note how the south-oriented Republican River tributary valleys are linked by north-south oriented through valleys with shorter north-oriented Plum Creek tributary valleys. The through valleys provide evidence of multiple south-oriented flood flow channels that once crossed the figure 4 map area. Flood waters initially flowed on a topographic surface at least as high as the highest figure 4 elevations today. The multiple south-oriented flood flow channels were probably interconnected or anastomosing and were being eroded into that earlier high level topographic surface. At that time the Plum Creek valley did not exist and the much larger Platte River valley north of the figure 4 map area did not exist. Headward erosion of what was then the deep Plum Creek valley beheaded the south-oriented flood flow channels. The north-oriented Plum Creek tributary valleys were eroded by reversals of south-oriented flood flow on north ends of south-oriented flood flow channels supplying flood water to what were then the actively eroding south-oriented Republican River tributary valleys. Generally the through valleys are shallow relative to the opposing valleys on either side, which suggests large volumes of flood flow were involved during the flood flow reversals. Some of the reversed flood flow responsible for eroding the north-oriented valleys probably was yet to beheaded flood flow from flood flow channels west of the actively eroding Plum Creek valley head. Because flood flow channels were anastomosing reversed flood flow on a newly beheaded flood flow routes could easily capture yet to be beheaded from flood flow.

Plum Creek-Republican River drainage divide area near Elwood

Figure 5: Plum Creek-Republican River drainage divide area near Elwood. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Plum Creek-Republican River drainage divide area south and east of the figure 3 map area and includes overlap areas with figure 3. Elwood is the town in the figure 5 north center area and Smithfield is the town in the figure 5 northeast quadrant. Plum Creek is the stream north of Smithfield and located along the figure 5 north edge. Other than north and east of the highway and railroad between Elwood and Smithfield all figure 5 drainage flows south to the Republican River. The east-southeast and south oriented Republican River tributary south of Smithfield is the East Branch Turkey Creek. The south-oriented Republican River tributary originating near the radio tower (located by highway east of Elwood) is the West Branch Turkey Creek. Elk Creek is the south-oriented stream originating just southwest from Elwood and flowing near the south-oriented highway to the figure 5 south edge. The East Branch Muddy Creek is the stream flowing from the north edge to the south edge near the figure 5 west edge. Note how the East and West Branches of Turkey Creek are linked by shallow through valleys to north-oriented Plum Creek valleys. Figure 6 below provides a detailed map better illustrating the linkages and the shallow through valleys. Note also how the south-oriented Republican River tributary valleys have eroded north into what appears to be a relatively level tableland. Flood waters responsible for eroding the south-oriented Republican River valleys headward definitely flowed across that tableland surface, which may be a flood eroded erosion surface. Badland landscape characteristics found where valleys have been eroded headward into that tableland suggest the underlying bedrock is easily eroded. Topographic map evidence does not permit identification of bedrock types, however the ease with which that bedrock has been eroded suggests the possibility the region may have been covered with flood deposited sediments, which were subsequently eroded as deep flood eroded valleys eroded headward into the region. Regardless of whether the figure 6 was covered with flood deposited sediments or not, the figure 6 map area was deeply eroded by south-oriented flood flow to what was at one time the newly eroded Republican River valley. The south-oriented Republican River tributary valleys eroded headward from that newly eroded east-oriented deep valley. Figure 7, 8, 9, and 10 below provide various views of those south-oriented Republican River tributary valleys and suggest the deep tributary valleys eroded headward into and along what was once a south-oriented anastomosing channel complex. Evidence for the anastomosing channel complex is not present on the tableland surface, but is found in the tributary valley complex south of the tableland.

Detailed map of Plum Creek-Republican River drainage divide area near Elwood

Figure 6: Detailed map of Plum Creek-Republican River drainage divide area near Elwood. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a detailed map view of the Plum Creek-Republican River drainage divide area near Elwood, which was seen in less detail in figure 5 above. Elwood is the town located near the figure 6 west edge and is located on a relatively level tableland into which Plum Creek and Republican River tributary valleys have been eroded. Southeast-oriented Plum Creek can be seen in the figure 6 northeast quadrant. The south-southeast oriented Republican River tributary in the figure 6 southeast quadrant is East Branch Turkey Creek. The south-oriented Republican River in the figure 6 south center area is the West Branch Turkey Creek. Figure 7 below illustrates the West Branch-East Branch Turkey Creek drainage divide area south of the figure 6 map area.   Note north-oriented Plum Creek tributary valleys (generally north of the west to east oriented highway and railroad). South of the highway valleys are south oriented and drain to the Republican River. The highway and railroad cross several shallow north-south oriented through valleys and are generally located on the Plum Creek-Republican River drainage divide. The through valleys and the similar alignments of the opposing valleys provide evidence south-oriented flood flow moved across the tableland surface prior to Plum Creek valley headward erosion. Flood flow was probably moving as sheet flow to what were then actively eroding south-oriented Republican River tributary valleys. The Republican River tributary valleys had eroded headward into the figure 6 south edge area when Plum Creek valley headward erosion beheaded the south-oriented flood flow. Flood waters on north ends of the beheaded flood flow routes or channels leading to the actively eroding Republican River tributary valleys reversed flow direction to flow north to the newly eroded Plum Creek valley. The reversed flood flow (probably aided by captured yet to be beheaded flood flow from further to the west) eroded the north-oriented Plum Creek tributary valleys and created the Plum Creek-Republican River drainage divide. The relatively level tableland surface into which the valleys have been eroded appears to be easily eroded and may be a flood eroded erosion surface cut into easily eroded bedrock and/or a depositional surface created by earlier deposition of flood transported sediments.

West Branch-East Branch Turkey Creek drainage divide area

Figure 7: West Branch-East Branch Turkey Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed map of the West Branch Turkey Creek-East Branch Turkey Creek drainage divide area south and east of the figure 6 map area and includes overlap areas with figure 6 (the figure 7 map area is also shown in less detail in figure 5 above). Smithfield is the town located in the figure 7 northeast corner. The East Branch Turkey Creek flows in a south-southeast direction from the figure 7 north edge (west of Smithfield) to the figure 7 south edge (figure 7 southeast corner area). The West Branch Turkey Creek is located just west of the figure center and flows in a south-southeast direction and flows from the figure 7 north edge to the south edge. In the figure 7 center area there is an isolated remnant of the tableland into which the south-oriented Republican River tributary valleys have been eroded. A shallow through valley in the section 22 northeast corner separates the tableland remnant from the tableland to the north. While not deep, the through valley provides evidence flood waters once flowed in a south-southwest direction from the present day East Branch Turkey Creek headwaters area into what is now the West Branch Turkey Creek valley. The flood flow route identified by the through valley is also evidence of a south-oriented anastomosing channel pattern, which existed at the time the south-oriented Republican River tributary valleys were being eroded headward into the region. Immediately south of the isolated tableland remnant is another shallow through valley linking a northeast-oriented East Branch Turkey Creek tributary valley with a southwest-oriented West Branch Turkey Creek tributary valley. That through valley provides evidence of another southwest-oriented flood flow route beheaded by headward erosion of the south-oriented East Branch Turkey Creek valley. The northeast-oriented East Branch Turkey Creek tributary valley was eroded by a reversal of flood flow on the northeast end of the beheaded southwest-oriented flood flow channel. Continuing south along the West Branch-East Branch Turkey Creek drainage divide other similar shallow through valleys provide further evidence of what was probably a shallow but, constantly changing south-oriented anastomosing channel complex, which existed as the deep West Branch Turkey Creek and East Branch Turkey Creek valleys eroded headward from what was then the newly eroded and deep east-oriented Republican River valley located to the south.

Elk Creek-Turkey Creek drainage divide area

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

Figure 8 illustrates the Elk Creek-Turkey Creek drainage divide area south of the figure 5 map area and includes overlap areas with figure 5. Elk Creek is the south oriented stream located immediately east of Union Ridge. East Muddy Creek is the south oriented stream located west of Union Ridge and which flows from the figure 8 northwest corner to the figure 8 southwest corner. The south oriented stream with woodland patches in its valley and located in the figure 8 east half is Turkey Creek. The East Branch Turkey Creek flows in a south direction from the figure 8 north edge to join south- and southeast-oriented West Branch Turkey Creek and then to flow south to the figure 8 south edge. Between Turkey Creek and Elk Creek is south-oriented Dry Creek, which originates south of the south-oriented West Branch Turkey Creek valley segment, and which flows to the figure 8 south edge. Note how the south-oriented Dry Creek headwaters are linked by shallow through valleys to the south-oriented West Branch Turkey Creek valley segment to the north. The deep southeast-oriented West Branch Turkey Creek valley segment eroded headward along one of several south-oriented anastomosing channels to behead south-oriented flood flow to what was then the actively eroding and deep Dry Creek valley. By doing so the deep West Branch Turkey Creek valley captured all flood flow in the south-oriented flood flow channels to the Dry Creek valley. Figure 9 below provides a detailed map to better illustrate these shallow through valleys. Other shallow through valleys along the Elk Creek-Dry Creek drainage divide provide evidence the deep Elk Creek valley eroded headward along one of several south-oriented anastomosing channels and beheaded southeast-oriented flood flow that was moving to what was then the actively eroding Dry Creek valley. Additional shallow through valleys can be seen in the figure 8 map area, although detailed maps provide better evidence. One interesting shallow through valley is located just north of Union Ridge and links headwaters of a south-oriented Elk Creek tributary (which joins Elk Creek south of Union Ridge) with a southeast-oriented Elk Creek valley segment north of Union Ridge. That shallow through valley provides evidence that at one time two diverging and then merging south-oriented flood flow channels were located on both sides of the present day Union Ridge. At that time flood water was flowing on a surface at least as high as the shallow through valley floor (almost as high as Union Ridge) and the deep Elk Creek valley had yet to be eroded (at least as far north as the Union Ridge north end).

Detailed map of West Branch Turkey Creek-Dry Creek drainage divide area

Figure 9: Detailed map of West Branch Turkey Creek-Dry Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a detailed map of the West Branch Turkey Creek-Dry Creek drainage divide area seen in less detail in figure 8 above. The West Branch Turkey Creek flows in a southeast direction from the figure 9 north edge (northeast quadrant) through section 35 to join south-southwest oriented East Branch Turkey Creek in section 1 in the figure 9 east center area. Turkey Creek flows south from the junction of the two Turkey Creek Branches to the figure 9 south edge (near the southeast corner). Dry Creek flows in a south-southeast direction from the figure 9 north edge (northwest quadrant) through section 33 and into section 4 and then flows in a south direction through section 9 to the figure 9 south edge. The south-oriented stream just east of Dry Creek and flowing through sections 3 and 10 to the figure 9 south is a Dry Creek tributary, which joins Dry Creek south of the figure 9 map area. Note how headwaters of the south-oriented Dry Creek tributary are linked by a shallow through valley in section 34 to a northeast oriented West Branch Turkey Creek tributary valley. Also note in the section 3 east center area a shallow through valley linking a northeast and southeast oriented West Branch Turkey Creek tributary valley with a south- and southwest-oriented tributary valley to the south-oriented Dry Creek tributary valley. These and other similar through valleys provide evidence headward erosion of the deep Turkey Creek-West Branch Turkey Creek valley occurred along one of several south-oriented anastomosing flood flow channels and beheaded south-oriented flood flow to what were then other actively eroding and deep south-oriented flood flow channels. Flood waters on the north and northeast ends of the beheaded flood flow channels reversed flow direction to erode northeast-oriented West Branch Turkey Creek tributary valleys. Headward erosion of the deep West Branch Turkey Creek valley (and as seen in figure 8 above headward erosion of the deep Elk Creek valley) beheaded all flood flow channels to what had been the actively eroding and deep south-oriented Dry Creek valley. Also as seen in figures above headward erosion of the deep Plum Creek (from the actively eroding Platte River valley head) beheaded all south-oriented flood flow to what had been the actively eroding Turkey Creek and Elk Creek valleys.

Republican River valley and south-oriented tributary valleys near Arapahoe

Figure 10: Republican River valley and south-oriented tributary valleys near Arapahoe. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Republican River valley and south-oriented tributary valleys near Arapahoe, Nebraska and is located south of the figure 8 map area and includes significant overlap areas with figure 8. Arapahoe is the town located in the figure 10 southwest quadrant. The Republican River is the east-southeast oriented river near the figure 10 south edge. Elk Creek is the south-oriented tributary flowing to the Republican River at Arapahoe. As previously stated the east-oriented Republican River valley eroded headward across the figure 10 map area to capture massive south-oriented flood flow. The present day south-oriented Republican River tributary valleys eroded headward from what was then the actively eroding and deep Republican River valley head. Little Antelope Creek is a relatively short south-southeast oriented Republican River tributary located immediately east of Elk Creek. Note how Little Antelope Creek headwaters are linked by a shallow through valley to a south-southwest oriented Elk Creek tributary valley. The shallow through valley provides evidence that at one time south-southeast flood flow moved from the present day Elk Creek valley to the what was then the actively eroding Little Antelope Creek valley. At that time the deep Little Antelope Creek valley had eroded headward from what then the deep and actively eroding east-oriented Republican River valley head and the deep Elk Creek did not yet exist. Headward erosion of the Republican River valley then permitted the deep Elk Creek valley to erode north and to behead the south-southeast oriented flood flow to the Little Antelope Creek valley. Just east of Little Antelope Creek is south-southeast oriented Big Antelope Creek. Note how the Big Antelope Creek headwaters are linked a shallow through valley to a northwest-oriented Elk Creek tributary valley. The deep Big Antelope Creek valley eroded headward from the actively eroding Republican River valley head prior to headward erosion of the Little Antelope Creek valley. It took longer for the Republican River valley to erode headward from the Big Antelope Creek valley location to the Elk Creek mouth and then for the deep Elk Creek valley to erode headward to behead flood flow to what was then the actively eroding Big Antelope Creek valley, which meant the Big Antelope Creek valley was able to erode further than the Little Antelope Creek valley. East of Big Antelope Creek is Dry Creek, which joins the Republican River near the figure 10 south center edge. East of Dry Creek is south-southeast oriented Turkey Creek, which has patches of woodlands in its valley and which joins the Republican River south of the figure 10 map area.

Additional information and sources of maps

This essay has only provided a sample of the drainage divide evidence supporting the “thick ice sheet that melted fast” geomorphology paradigm. Many additional examples could be provided, especially by using more detailed topographic maps. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of supporting data. Maps used in this study were created by the United States Geological Survey and can be purchased in hard copy from the United States Geological Survey or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories located in major research libraries and elsewhere throughout the United States and in other countries. Illustrations used in this essay were created using National Geographic Society TOPO software and digital data. National Geographic Society digital maps can be purchased from the National Geographic Society or from dealers offering National Geographic Society digital maps.