A geomorphic history based on topographic evidence

The Elkhorn River-Missouri River drainage divide area in Washington, Douglas, and Sarpy Counties, Nebraska is drained by the southeast-oriented Papillion Creek valley stem, which is located between the south oriented Elkhorn and Missouri River valleys. The south oriented Elkhorn River is located west of the Missouri River and flows to the south and east oriented Platte River, which flows along the Sarpy County south border to join the south-oriented Missouri River. Landforms in the drainage divide area are interpreted to have been eroded during an immense south-southeast oriented glacial melt water flood. Headward erosion of the present day Missouri River valley and its various tributary valleys occurred in an identifiable sequence as they captured the south-southeast oriented flood waters. The Platte River-Elkhorn River valley eroded west and north from what was then the newly eroded Missouri River valley. At about the same time the Papillion Creek valley system eroded headward to capture the south-southeast oriented flood flow. Headward erosion of the south-southeast oriented Elkhorn River valley next beheaded southeast-oriented flood flow to Papillion Creek headwaters. Flood flow across the drainage divide area ended as headward erosion of the Missouri River valley and its tributary valleys beheaded all south-southeast oriented flood flow routes.

Preface:

• The purpose of this essay is to use topographic map interpretation methods to explore Elkhorn River-Missouri River drainage divide area landform origins in Washington, Douglas, and Sarpy 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 immense melt water floods north into space the ice sheet had once occupied.

• If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Elkhorn River-Missouri River drainage divide area landform origins evidence in Washington, Douglas, and Sarpy 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.

Elkhorn River-Missouri River drainage divide area location map

Figure 1: Elkhorn River-Missouri 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 an Elkhorn River-Missouri River location map. Nebraska is the state occupying most of the figure 1 west half and Kansas is the state south of Nebraska along the figure 1 west half south edge. Iowa is the state occupying most of the figure 1 east half with Missouri being the state located south of Iowa in the figure 1 southeast corner area. The Missouri River is the south-southeast oriented river forming the Nebraska-Iowa border and the Nebraska-Missouri and Kansas-Missouri border further to the south. The Elkhorn River flows from the figure 1 northwest corner to Neligh, Norfolk, Pilger, West Point, Scribner, Hooper, and Elkhorn before joining the Platte River west of Omaha, Nebraska. Generally the Elkhorn River is southeast oriented, although downstream from Hooper it becomes a south-southeast and south oriented river before reaching the Platte River. Downstream from its confluence with the Elkhorn River the Platte River flows south and east to join the south-southeast oriented Missouri River. The Platte River flows in a northeast direction from the figure 1 west edge to Columbus, Nebraska and then gradually turns at North Bend and Fremont to become a southeast and south oriented river to reach its confluence with the south-southeast and south oriented Elkhorn River. The Elkhorn River-Missouri River drainage divide area in Washington, Douglas, and Sarpy Counties investigated in this essay is located between the south-southeast and south oriented Elkhorn River segment south of Hooper and the south-southeast oriented Missouri River. Other essays illustrate and describe Elkhorn River-Missouri River drainage divide areas north of Hooper and include the Logan Creek-Missouri River drainage divide area in Thurston, Burt, and Dakota Counties essay; the Elkhorn River-Logan Creek drainage divide area in Wayne, Stanton, and Cuming Counties essay; the Bow Creek-Logan Creek and other drainage divides in Cedar, Dixon, and Dakota Counties essay; and the Bazile Creek-North Fork Elkhorn River drainage divide area in Knox, Pierce, and Antelope Counties essay (these essays can be found under Elkhorn River on the sidebar category list). Evidence presented in these and other Missouri River drainage basin landform origins research project essays has built a strong for immense south- and southeast-oriented floods moving across northeast Nebraska prior to headward erosion of present day river valleys. Flood waters were derived from a rapidly melting thick North American ice sheet, the margin of which was located at that time north of the figure 1 map area. Melt water floods sliced a gigantic south-oriented ice-walled and bedrock-floored valley into the ice sheet surface and prior to Missouri River valley headward erosion massive floods from that valley would have flowed across eastern Nebraska (see essays under James River on sidebar category list). Also, prior to Missouri River and Niobrara River valley headward erosion immense southeast-oriented melt water floods moved parallel to the ice sheet southwest margin into Nebraska (see essays listed under Niobrara River on sidebar category list).

Elkhorn River-Missouri River drainage divide area detailed location map

Figure 2: Elkhorn River-Missouri 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 Elkhorn River-Missouri River drainage divide area in Washington, Douglas, and Sarpy Counties, Nebraska. The Missouri River flows from the figure 2 north edge to the figure 2 south edge and flows south along the east edge of the city of Omaha, Nebraska. West of the Missouri River is Nebraska and east of the Missouri River is Iowa. Colfax, Dodge, Washington, Saunders, Douglas, Sarpy, and Cass are Nebraska county names and the county boundaries are shown. Harrison, Shelby, Pottawattamie, and Mills are Iowa county names. The Platte River flows from the figure 2 west edge along the Colfax and Dodge County south borders and then flows along the Saunders-Douglas border before turning east to flow along the Sarpy-Cass County border to reach the south oriented Missouri River. The Elkhorn River flows south into north central Dodge County and then turns to flow to and along the Dodge-Washington County border before flowing south in west Douglas County to join the Platte River in northwest Sarpy County. Logan Creek is the south-oriented stream joining the Elkhorn River near Hooper. Bell Creek flows south through western Washington County and joins the Elkhorn River near Arlington, on the Washington County southwest boundary. Big Papillion Creek originates in northern Washington County and flows south into Douglas County and then southeast across the Omaha urban area to join Papillion Creek and then the Missouri River near Bellevue. East of Big Papillion Creek is Little Papillion Creek, which originates in southern Washington County and flows south across the Omaha urban area to join Big Papillion Creek just west of Bellevue. West Papillion Creek originates northwest of Elkhorn (near the Elkhorn River and west of Omaha) and flows in a southeast direction to also join Big Papillion Creek just west of Bellevue. The figure 2 drainage network evolved during an immense south-southeast oriented flood which flowed across the entire figure 2 map area. Evidence for flood flow movements is documented in the topographic maps below. Flood waters were systematically captured by headward erosion of the Missouri River valley and its various tributary valleys. The Platte River valley eroded west, north, northwest, and then southwest from what was then the actively eroding Missouri River valley head to capture flood waters further to the west. The Papillion Creek valley complex next eroded northwest and west to capture the south and southeast oriented flood flow. At about the same time the Elkhorn River valley eroded north and northwest to capture southeast and south oriented flood water to the newly eroded Platte River valley and the Papillion Creek valley system. Headward erosion of the Missouri River valley and its tributary valleys north and northwest of the figure 2 map area eventually beheaded all southeast and south oriented flood flow routes to the figure 2 map region.

Elkhorn River-Missouri River drainage divide in north Washington County

Figure 3: Elkhorn River-Missouri River drainage divide area in north Washington County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Elkhorn River-Missouri River drainage divide area in northern Washington County. The south-southeast oriented Missouri River is located near the figure 3  east edge and the south-southeast oriented Elkhorn River is located near the figure 3 west edge (south half). Clark Creek is the south-oriented Elkhorn River tributary near the figure 3 west edge (north half). Bell Creek is the south-oriented stream flowing from the figure 3 north edge to the south edge and located between the Elkhorn River and the Missouri River. Bell Creek flows to the Elkhorn River south of the figure 3 map area. Blair is the town located in the figure 3 southeast corner, Nickerson is the town located in the figure 3 southwest corner. Herman is the town located on the edge of the Missouri River valley near the figure 3 north edge. New York Creek is the south, east-southeast, northeast, and north oriented stream flowing to the Missouri River valley edge just south of Herman. Hill Creek is the northeast-oriented Missouri tributary north of New York Creek. The southeast and south oriented stream west of Blair and south of New York Creek is Big Papillion Creek, which flows south between the Elkhorn River and Missouri River to eventually join the Missouri River south of Omaha (see figure 9 below). While south-oriented drainage routes predominate in the figure 3 map area there are several north and northeast oriented (barbed) Missouri River tributaries. These north and northeast oriented Missouri River tributaries can best be explained by headward erosion of the deep south-southeast oriented Missouri River valley to behead multiple south- and southeast-oriented flood flow routes such as might be found in a large-scale flood formed south-oriented anastomosing channel complex. Headward erosion of the deep Missouri River valley would have beheaded these south-oriented flood flow channels one channel at a time. Flood waters on the north ends of the newly beheaded channels would have reversed flow direction to flow north to the newly eroded south-southeast oriented Missouri River valley. Because the flood flow channels were anastomosing reversed flow in a newly beheaded flood flow channel could capture yet to be beheaded flood flow from adjacent flood flow channels to the west. Captured flood waters from these yet to beheaded flood flow channels enabled reversed flow channels to erode valleys southwest and west. New York Creek illustrates how this process occurred. Not only did headward erosion of the New York Creek valley behead south-oriented flood flow to what was then the actively eroding south-oriented Big Papillion Creek valley, but it also eroded its valley north along one of the captured yet to be beheaded south-oriented flood flow routes.

New York Creek-Big Papillion Creek drainage divide area

Figure 4: New York Creek-Big Papillion Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the New York Creek-Big Papillion Creek drainage divide area seen in less detail in figure 3 above. New York Creek is located in the figure 4 northwest quadrant and flows east and northeast to the figure 4 north center edge. North of the figure 4 map area New York Creek turns to flow in a north direction to join the south-southeast oriented Missouri River as a barbed tributary. Big Papillion Creek is located in the figure 4 southwest quadrant and flows in a southeast direction to the figure 4 south center edge. South of figure 4 Big Papillion Creek turns to flow south between the Elkhorn River and the Missouri River before finally turning to flow in a southeast direction to the Missouri River. Lippincott Creek and the east and northeast oriented streams south of Lippincott Creek also flow to the Missouri River, some as barbed tributaries. Note how New York Creek has several north-oriented tributaries. For example, one of the major figure 4 north-oriented New York Creek tributary valleys is located in section 19 (just east of the figure 4 center). Note how that tributary begins as a south-southeast oriented stream and then turns to flow north and north-northwest before entering the northeast-oriented New York Creek valley. Also note the through valley south of the U-turn linking the north-oriented tributary valley with the south-oriented Big Papillion Creek valley. The through valley is evidence that at one time flood waters moved south from what is today the New York Creek drainage basin to the south-oriented Big Papillion Creek valley. A similar through valley can be seen in the southeast corner of section 23 to the east. That section 23 through valley also links a north and north-northwest oriented New York Creek tributary with a south-oriented Big Papillion Creek tributary. Shallower and higher level through valleys cross the drainage divide further to the west. The north-oriented New York Creek tributary valleys were eroded by reversals of flood flow when headward erosion of the south-southeast oriented Missouri River valley beheaded south-oriented flood flow routes moving flood water to what was then the actively eroding south-oriented Big Papillion Creek valley. Flood waters on the north ends of the beheaded flood flow routes reversed flow direction to flow north to the much deeper south-southeast-oriented Missouri River valley.

Coulee Creek- East Fork Big Papillion Creek drainage divide area

Figure 5: Coulee Creek- East Fork Big Papillion Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Coulee Creek-East Fork Big Papillion Creek drainage divide area southwest of Blair, Nebraska. Blair is located in the figure 5 northeast quadrant and sits on the edge of the south-southeast oriented Missouri River valley. Big Papillion Creek is the south-southeast oriented stream located near the figure 5 west edge. South Creek is the north-oriented stream with a wooded (green) valley in the figure 5 north center. South of South Creek in the figure 5 south center is south-oriented East Fork Big Papillion Creek. Note how a railroad line is located in the East Fork Big Papillion Creek valley. That railroad line continues in a north-northeast direction from the East Fork Big Papillion Creek valley into the north-northeast oriented Coulee Creek valley, which like the South Creek valley drains to the south-southeast oriented Missouri River as a barbed tributary. The railroad line is located in a through valley linking the north-northeast oriented Coulee Creek valley with the south-oriented East Fork Big Papillion Creek valley. While not as deep as the Coulee Creek-East Fork Big Papillion Creek through valley there is also a through valley linking the north-oriented South Creek valley with the south-oriented East Fork Big Papillion Creek valley. Study of the figure 5 map area east of the Coulee Creek-East Fork Big Papillion Creek through valley reveals additional although less obvious through valleys linking north-oriented Missouri River tributary valleys with south- and southeast-oriented valleys. Again the figure 5 evidence can best be explained by headward erosion of the present day valleys into the figure 5 map area to capture an immense south- and southeast-oriented flood, which initially flowed on a topographic surface at least as high as the highest figure 5 elevations today, if not higher. Initially flood waters flowed south to what was then the actively eroding East Fork Big Papillion Creek valley (and also the Big Papillion Creek valley to the west). Headward erosion of the deep Missouri River valley then beheaded south-oriented flood flow routes to the East Fork Big Papillion Creek valley. Flood waters on the north ends of the beheaded Coulee Creek and South Creek flood flow routes reversed flow direction to flow north to the newly eroded and much deeper Missouri River valley. The reversed flood flow captured yet to be beheaded flood flow from flow routes further to the west and with the aid of such captured flood water were able to erode the north-oriented Coulee Creek and South Creek valleys.

Elkhorn River-Missouri River drainage divide in south Washington County

Figure 6: Elkhorn River-Missouri River drainage divide in south Washington County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Elkhorn River-Missouri River drainage divide area in south Washington County and shows in less detail the region southwest of Blair seen in more detail in figure 5 above. Blair is the city located along the figure 6 north center edge. The Missouri River meanders in a southeast direction from Blair to the figure 6 east center edge and then east of figure 6 turns to flow south and the Missouri River valley can again be seen in the figure 6 southeast corner. The south-southeast oriented river in the figure 6 southwest corner is the Elkhorn River. Elk City is the small town in the figure 6 southwest corner. Big Papillion Creek flows south and southeast from just west of the figure 6 north center edge to Bennington near the figure 6 south center edge. The southeast-oriented stream joining Big Papillion Creek near Kennard just northwest of the figure 6 center area is the Northwest Branch of Big Papillion Creek. The East Fork Big Papillion Creek flows south and southwest to also join Big Papillion near Kennard. In the figure 6 southeast quadrant are headwaters of south-oriented Little Papillion Creek. North of the south-oriented Little Papillion Creek headwaters are north oriented Missouri River tributaries including Deer Creek, Turkey Creek, Moores Creek, and Long Creek. Close study of figure 6 reveals these north oriented Missouri River tributaries are all linked by through valleys with south-oriented Little Papillion Creek headwaters valleys. These multiple north-south oriented through valleys provide further evidence south-oriented anastomosing flood flow channels were beheaded by headward erosion of the deep southeast-oriented Missouri River valley. Flood waters were flowing to what was then the actively eroding Little Papillion Creek drainage basin and flood waters on the north ends of the beheaded flood flow routes reversed flow direction to flow north to the newly eroded and much deeper Missouri River valley. The Elkhorn River-Missouri River drainage divide area shown in figure 6 is almost completely drained by the south-oriented Big Papillion Creek drainage network. The exceptions are primarily the north- and northeast-oriented Missouri River tributaries, which as already described originated with flood flow reversals when Missouri River valley headward erosion beheaded south-oriented flood flow to what was then the actively eroding Big Papillion Creek valley system. Fort Calhoun is the town located in the figure 6 east center area. Figure 7 below provides a more detailed map of drainage divides in the region immediately southwest of the Fort Calhoun location.

Moores Creek-Little Papillion Creek drainage divide area

Figure 7: Moores Creek-Little Papillion Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Moores Creek-Little Papillion Creek drainage divide area southwest of the town of Fort Calhoun seen in less detail in figure 6 above. Little Papillion Creek flows south and south-southeast from the figure 7 center area to the figure 7 south center edge. Long Creek flows in a southeast and north direction in the figure 7 northwest quadrant. Note how a north-northwest Long Creek tributary is linked by a through valley in the section 21 southwest corner with the south-southeast-oriented Little Papillion Creek valley. The north-oriented streams in section 22 flowing into section 15 and to the figure 7 north edge are Moores Creek headwaters. Note how through valleys link all of the north-oriented Moores Creek headwaters valleys with the south-oriented Little Papillion Creek valley or its south-oriented tributary valleys to the east. Along the figure 7 east edge area in the north half is northeast-oriented Turkey Creek. Note how Turkey Creek headwaters are also linked by a through valley with a south-oriented Little Papillion Creek tributary valley. In the figure 7 southeast corner is northeast-oriented Deer Creek, which south of the figure 7 map area is also linked by a through valley with a south-oriented Little Papillion Creek tributary. As seen in figure 6 above Long Creek, Moores Creek, Turkey Creek, and Deer Creek all flow in a north or northeast direction to join the southeast-oriented Missouri River as barbed tributaries. The barb tributaries, the valley orientations, and the through valleys linking the north-oriented stream valleys with the south-oriented Little Papillion Creek valley system all provide evidence of a south-oriented anastomosing channel complex that was beheaded in sequence by Missouri River valley headward erosion. Flood waters on the north ends of the beheaded south-oriented flood flow channels reversed flow direction to flow north to the newly eroded and much deeper Missouri River valley. Flood flow to the figure 7 map area ended when the Long Creek valley eroded west to capture southeast-oriented flood flow to what was then the actively eroding Little Papillion Creek valley and to divert the flood water north and northeast to newly eroded and much deeper Missouri River valley.

Elkhorn River-North Branch West Papillion Creek drainage divide area

Figure 8 illustrates the Elkhorn River-North Branch West Papillion Creek drainage divide area located south of Elk City, which was seen in the figure 6 southwest corner area. The south oriented Elkhorn River valley is located along the figure 8 west edge and the Elkhorn River channel is located just west of the figure 8 map area. Elk City is located along the figure 8 north edge (west half). The North Branch West Papillion Creek flows from the figure 8 north center area to the figure 8 southeast corner. From figure 8 it flows in a south-southeast and south direction to join West Papillion Creek. Northeast-oriented drainage in the figure 8 northeast corner area flows to an east-oriented tributary to southeast oriented Big Papillion Creek (located just west of the town of Bennington-see figure 6). Shallow through valleys link those northeast-oriented Big Papillion Creek valleys with the south-southeast oriented North Branch West Papillion Creek valley. Further west along the figure 8 north edge are north-oriented tributaries to a northeast and east-oriented tributary which joins Big Papillion Creek near Washington (see figure 6). Again shallow through valleys link the north-oriented valleys with the North Branch West Papillion Creek valley. The through valleys provide evidence headward erosion of the Big Papillion Creek valley beheaded and reversed south-oriented flood flow to what was then the newly eroded North Branch West Papillion Creek valley. Note how the North Branch West Papillion Creek begins as a northeast-oriented stream and then turns to flow in an east-southeast direction before turning to flow in south-southeast direction. Also note the southeast- and east-northeast oriented North Branch West Papillion Creek tributary originating in section 24 and joining the North Branch of West Papillion Creek in the figure 8 southeast corner. Both the North Branch West Papillion Creek and the tributary headwaters valleys have been eroded into what appears to be a relatively flat erosion surface located adjacent to the south-oriented Elkhorn River valley. The erosion surface was probably eroded by south-oriented flood water moving across the figure 8 map region prior to headward erosion of the present day valley systems. The North Branch West Papillion Creek valley probably eroded headward into the figure 8 map region first. At approximately the same time the deep south-oriented Elkhorn River valley eroded headward into the region and captured flood flow in the west while headward erosion of the Big Papillion Creek valley (east of the figure 8 map area) beheaded south- and southwest-oriented flood flow further to the east.

Papillion Creek-Missouri River drainage divide area south of Omaha

Figure 9: Papillion Creek-Missouri River drainage divide area south of Omaha. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Papillion Creek-Missouri River drainage divide area south of Omaha. The Missouri River is located in the figure 9 northeast corner and the Missouri River valley continues in a southeast and south-southeast direction east of the figure 9 map area. Big Papillion Creek flows in a southeast direction from the figure 9 northwest edge and joins Papillion Creek in the figure 9 south center. Papillion Creek flows in an east-southeast direction from the figure 9 west edge to join Big Papillion Creek and then to flow in a southeast direction to the figure 9 south edge. South of figure 9 Papillion Creek flows in a southeast direction to eventually join the south-southeast oriented Missouri River. West of figure 9 Papillion Creek is formed at the confluence of South Papillion Creek and West Papillion Creek. Figure 8 above illustrated the headwaters area of the North Branch West Papillion Creek and figure 10 below illustrates the headwaters area for West Papillion Creek. South Papillion Creek headwaters, while not originating on the Elkhorn River valley edge (as the North Branch West Papillion Creek and West Papillion Creek headwaters do) originates near the Elkhorn River and are linked by through valleys with the south-oriented Elkhorn River valley and the adjacent Platte River valley (which is located just west of the Elkhorn River valley at that location). Figure 9 illustrates north-oriented Missouri River tributaries and through valleys linking those north-oriented Missouri River tributary valleys with the southeast-oriented Papillion Creek drainage system. The north-oriented tributaries and the through valleys provide evidence of multiple south-oriented flood flow channels moving flood waters south into what was at one time the actively eroding southeast-oriented Papillion Creek valley. The multiple north-south valleys suggests the presence of a south-oriented anastomosing channel complex, which was first captured by headward erosion of the Papillion Creek valley, next by headward erosion of the Big Papillion Creek valley, and finally by headward erosion of the much deeper Missouri River valley. Headward erosion of the deep Missouri River valley beheaded the flood flow channels to what was then the newly eroded Papillion Creek valley system. Flood waters on the north ends of the beheaded flood flow channels reversed flow direction to flow north to the newly eroded and much deeper Missouri River valley.

Elkhorn River-West Papillion Creek drainage divide west of Omaha

Figure 10: Elkhorn River-West Papillion Creek drainage divide west of Omaha. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the Elkhorn River-West Papillion Creek drainage divide area west of Omaha. Elkhorn, Nebraska is the town located in the figure 10 south center. Waterloo is the town located west of Elkhorn near the figure 10 west edge. The Elkhorn River flows in a south-southeast direction from the figure 10 northwest corner to the figure 10 south edge. St. John Seminary is the school located on the bluff adjacent to the Elkhorn River valley in the figure 10 northwest quadrant. West Papillion Creek flows in a south and south-southeast direction immediately east of St. John Seminary along the Elkhorn River valley edge to Elkhorn and then turns to flow in an east-southeast and southeast direction to the figure 10 southeast corner. Note several unnamed south-southeast oriented West Papillion Creek tributary valleys. The multiple south-southeast oriented valleys suggest a large south-southeast oriented flood flowed across the figure 10 map region at the time the West Papillion Creek valley eroded headward into the region. Flood waters were probably moving on a topographic surface at least as high as the highest present day elevations and were probably eroding a south-southeast oriented anastomosing channel complex into that topographic surface. Headward erosion of what was then a deep southeast-oriented West Papillion Creek valley from what was then the actively eroding Missouri River valley head captured flood waters from the south-southeast anastomosing channels and diverted the flood waters southeast to the newly eroded Missouri River valley. At about the same time the deeper Elkhorn River valley eroded headward from what was then the actively eroding Platte River valley head to capture south-southeast oriented flood water, which up until that time had been moving to the newly eroded West Papillion Creek valley. Being a deeper valley the Elkhorn River valley was more successful in capturing the south-southeast oriented flood water and was able to erode further north-northwest and northwest to capture significant amounts of addition south-southeast and southeast oriented flood water. As previously noted headward erosion of the North Branch West Papillion Creek valley and of the Big Papillion Creek valleys also beheaded south-southeast oriented flood flow channels to the newly eroded West Papillion Creek valley.

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.