A geomorphic history based on topographic evidence

The Platte River-Salt Creek drainage divide area in Butler, Saunders, and Lancaster Counties was eroded by an immense south-southeast and southeast oriented flood. Flood waters were first captured by headward erosion of the south-southeast and east oriented Platte River valley and the southeast-oriented Wahoo Creek valley from that actively eroding Platte River valley. The northeast-oriented Salt Creek valley eroded headward from the southeast-oriented Wahoo Creek valley to capture southeast flood flow channels further to the west. Shortly thereafter continued headward erosion of the Wahoo Creek valley beheaded south-southeast oriented flood flow to the eastern Salt Creek valley while headward erosion of Platte River valley further to the north beheaded south-southeast and southeast oriented flood flow routes to the newly eroded Wahoo Creek drainage basin and then to western Salt Creek valley. Evidence for the flood flow includes Salt Creek, Wahoo Creek, and Platte River tributary valley orientations and through valleys linking north-northwest and northwest oriented Platte River and Wahoo Creek tributary valleys with south-southeast and southeast oriented Salt Creek tributary valleys.

Preface:

• The purpose of this essay is to use topographic map interpretation methods to explore Platte River-Salt Creek drainage divide area landform origins in Butler, Saunders, and Lancaster 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-Salt Creek drainage divide area landform origins in Butler, Saunders, and Lancaster 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-Salt Creek drainage divide area location map

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

Figure 1 provides a location map for the Platte River-Salt Creek drainage divide area in Butler, Saunders, and Lancaster Counties, Nebraska. Nebraska is the state occupying the figure 1 western two-thirds and Iowa is the state east of Nebraska, except in the southeast corner. The state located in the southeast corner is Missouri and Iowa is the state located north of Missouri. The south-southeast oriented Missouri River is located along the Nebraska east border. The Platte River flows in a northeast direction from the figure 1 west edge (south half) to North Bend. At North Bend the Platte River turns so as to flow in a southeast direction to Fremont and Valley and then in a south-direction to Ashland. Near Ashland the Platte River flows in a northeast and east direction to join the Missouri River near Plattsmouth. Salt Creek is the unlabeled stream flowing in a northeast direction from Lincoln to join the Platte River near Ashland. Wahoo Creek is the Platte River tributary flowing in a southeast direction from Wahoo (north of Lincoln) to join the Platte River near Ashland (Salt Creek joins Wahoo Creek and Wahoo Creek then joins the Platte River). West of Wahoo Creek is Oak Creek, an unlabeled southeast-oriented Salt Creek tributary flowing from Valparaiso to Lincoln. And west of Oak Creek is southeast-oriented Big Blue River, which flows into Kansas to join the Kansas River (which is a Missouri River tributary). South and southeast of Salt Creek are headwaters of unlabeled southeast-oriented Missouri River tributaries. The Platte River-Wahoo Creek drainage divide area landform origins in Saunders County addresses a nearby drainage divide area and can be found under Platte River on the sidebar category list.  This essay addresses Platte River-Salt Creek drainage divide area evidence west of the Platte River-Wahoo Creek drainage divide area and east of the Platte River-Big Blue River drainage divide area. The essay also addresses Wahoo Creek-Salt Creek drainage divide area evidence. Essays found under Elkhorn River on the sidebar category list addressed landform origins in northeast Nebraska. These and hundreds of other Missouri River drainage basin landform origins research project essays published on this website build a very strong case for immense southeast and south-southeast oriented glacial melt water floods moving into and across Nebraska. These floods were captured by headward erosion of the northeast-oriented Salt Creek valley and diverted to what was then the newly eroded Missouri River valley. Shortly thereafter headward erosion of the Platte River valley captured the flood waters and beheaded all flood flow routes to the newly eroded Salt Creek valley.

Platte River-Salt Creek drainage divide area detailed location map

Figure 2: Platte River-Salt Creek 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-Salt Creek drainage divide area. Polk, Butler, Saunders, Douglas, Sarpy, York, Seward, Lancaster, Cass, and Otoe are Nebraska county names and the county boundaries are shown. The south-southeast oriented Missouri River is located near the figure 2 east edge and Iowa is located east of the Missouri River. The Platte River flows from the figure 2 west edge and forms the Polk and Butler County northern border, the Saunders County north and east border, and the Cass County northern border. Salt Creek flows in a northeast direction from Lincoln in Lancaster County to join southeast-oriented Wahoo Creek at Ashland in southeastern Saunders County. Wahoo Creek flows in a north-northwest and northeast direction from Touhy in southwest Saunders County to Wahoo and then turns to flow in southeast direction to Ashland and then to join the Platte River. Sand Creek is a southeast-oriented stream, which originates near the Platte River in northwest Saunders County and which joins Wahoo Creek at Wahoo. Several labeled southeast oriented tributaries join northeast-oriented Salt Creek and from east to west are Rock Creek, Little Salt Creek, and Oak Creek. These streams have southeast-oriented tributaries and there are additional unlabeled southeast-oriented Salt Creek tributaries shown as well. Note also the presence of north and northwest oriented Salt Creek tributaries from the south. While not included in the Platte River-Salt Creek drainage divide area discussed here these north and northwest oriented Salt Creek tributaries provide evidence supporting the interpretation Salt Creek headward erosion captured southeast and south-southeast oriented flood flow. North and northwest oriented tributary valleys were eroded by reversals of flood flow on the north and northwest ends of beheaded south- and southeast-flood flow routes. Also note in northeast Butler County north-northwest and north oriented Skull and Bone Creeks, which flow to the Platte River. The Skull and Bone Creek valleys were also eroded by reversals of flood flow on the north ends of beheaded south- and southeast-oriented flood flow routes. Southeast-oriented Salt Creek valleys were eroded by headward erosion of southeast-oriented flood flow channels from the north wall of what was then the newly eroded Salt Creek valley. Headward erosion of southeast-oriented Salt Creek tributary valleys ended when Wahoo Creek valley and later Platte River valley headward erosion captured the south-oriented flood flow, and beheaded the flood flow to what had been actively eroding Salt Creek tributary valleys.

Bone Creek-Skull Creek drainage divide area

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

Figure 3 uses reduced size maps to illustrate the Bone Creek-Skull Creek drainage divide in northeast Butler County and immediately south of the Platte River valley. The east-northeast oriented Platte River can just barely be seen in the figure 3 northwest corner. David City is the town located in the figure 3 southwest corner. Octavia is the smaller town located in the figure 3 northwest quadrant (near southeast edge of Platte River valley). Bone Creek flows in a northwest direction from the figure 3 south center edge to the figure 3 west center area and then flows in a north direction to join the Platte River just north of the figure 3 north edge (west half). Skull Creek is located in the figure 3 east half and flows in a north-northwest direction from the figure 3 south edge to the figure 3 north edge and joins the Platte River north of the figure 3 map area. Bone Creek and Skull Creek provide evidence of south and southeast oriented flood flow channels that were beheaded by Platte River valley headward erosion. Prior to Platte River valley headward erosion an immense southeast and south-southeast oriented flood flowed across Nebraska. Flood waters probably moved in flood eroded anastomosing channels, which had been eroded into a topographic surface at least as high as the highest Nebraska elevations today. Headward erosion of the Platte River valley captured the southeast and south-southeast oriented flood flow and diverted the flood waters to what was then the newly eroded and deep Missouri River valley. Flood waters on the north ends of beheaded south-oriented flood flow routes reversed flow direction to flow in a north, north-northwest, or northwest direction to the newly eroded and deeper Platte River valley. Because Platte River valley headward erosion beheaded flood flow channels one channel at a time (from east to west) and because the flood flow channels were anastomosing (interconnected) reversed flood flow on newly beheaded flood flow channels could usually capture yet to be reversed flood flow from flood flow channels further to the west. Such captures of yet to be beheaded flood flow provided the quantities of flood water required to erode significant north-oriented Platte River tributary valleys. Northeast-oriented Skull Creek tributary valleys may have been eroded by yet to be beheaded south-oriented flood flow captured by reversed flood flow in what was then the newly beheaded Skull Creek flood flow channel.

Skull Creek-Oak Creek drainage divide area

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

Figure 4 illustrates the Bone Creek-Skull Creek drainage divide area in the Bone Creek-Skull Creek headwaters area south of the figure 3 map area and includes overlap areas with figure 3. David City is the town located in the figure 4 northwest corner. Brainard is the smaller town located in the figure 4 south center area. A small U.S. Military Reservation is located northeast of Brainard. Skull Creek headwaters are located in the figure 4 northeast quadrant (generally north and east of the U.S. Military Reservation). Skull Creek originates as a northeast, southeast, and northeast oriented stream in the area immediately north of the Military Reservation and then turns to flow in a north-northwest direction to the figure 4 north edge. Northwest-oriented Bone Creek headwaters are located in the figure 4 northwest quadrant (in the region immediately east of David City). Near Brainard are headwaters of southeast-oriented Middle Oak Creek and North Oak Creek headwaters are located south of the Military Reservation. Hunters Slough is a south-southeast oriented Oak Creek tributary located on the same alignment as the north-northwest oriented Skull Creek valley segment. East and northeast oriented drainage in the figure 4 northeast quadrant (east of Skull Creek and Hunters Slough) is flowing to Wahoo Creek (see figure 2). Note how Oak Creek turns to flow in a south-southeast direction in the figure 4 southeast corner, and is flowing along the Skull Creek-Hunters Slough alignment. The north-northwest to south-southeast Skull Creek-Hunters Slough-Oak Creek alignment probably represents a former south-southeast oriented flood flow channel alignment, which will be seen further to the south in figures 7 and 9 below. Headward erosion of the northeast-oriented Salt Creek valley captured the south-southeast oriented flood flow channel and deepened the channel as the deeper Salt Creek valley eroded north-northwest along the channel. Headward erosion of the Salt Creek valley probably deepened the channel enough that headward erosion of Wahoo Creek tributary valleys were not deep enough to capture the south-southeast oriented flood flow to the northeast-oriented Salt Creek valley. Headward erosion of the deeper Platte River valley did behead the south-southeast oriented flood flow channel and flood waters on the north end of the beheaded flood flow channel reversed flow direction to flow in a north-northwest direction to the newly eroded Platte River valley. The reversal of flood flow eroded the north-northwest oriented Skull Creek valley and also created the Skull Creek-Hunters Slough drainage divide. The east oriented Skull Creek headwaters valley was probably eroded by yet to be beheaded southeast-oriented flood flow moving along the present day Bone Creek alignment, which was captured by reversed flood flow in the Skull Creek valley.

Detailed map of Skull Creek-North Oak Creek drainage divide area

Figure 5: Detailed map of Skull Creek-North Oak Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 5 provides a detailed map of the Skull Creek-Middle and North Oak Creek drainage divide area seen in less detail in figure 4 above. The U.S. Military Reservation is located in the figure 5 southeast quadrant and can be used as a reference point. Northwest-oriented drainage in the figure 5 northwest corner represents the Bone Creek headwaters area. North-oriented drainage in section 29 in the figure 5 northwest quadrant north of the figure 5 map area turns to flow in a northeast direction to join north-northwest oriented Skull Creek. South-oriented drainage in sections 5 and 4 represents headwaters of southeast-oriented Middle Oak Creek while south-oriented located south of the U.S. Military Reservation represents headwaters of southeast-oriented North Oak Creek. Skull Creek originates as northwest-oriented stream in the section 4 northwest corner and then makes an abrupt turn to flow in a northeast direction across section 32 before turning to flow in a southeast direction across section 34 and then turns again to flow in a northeast direction in section 2 (along the section 2 north edge). Note in the section 5 northeast corner and section 4 northwest corner there is a through valley linking the Skull Creek headwaters with the south-southeast oriented Middle Oak Creek headwaters. Also note a through valley in the section 32 southeast corner and section 33 southwest corner linking the Skull Creek headwaters valley with north-northwest oriented headwaters of the north-oriented Skull Creek tributary in section 32. Further note the through valleys in the section 30 southeast corner and the section 29 southwest corner linking those north-northwest-oriented Skull Creek tributary headwaters with the north-northwest oriented Bone Creek headwaters in section 30. Many more such through valleys can be seen with a close study of figure 5 evidence. While the pattern illustrated is not simple, the through valleys provide evidence of multiple south-southeast and southeast oriented anastomosing flood flow channels that crossed the figure 5 map area prior to headward erosion of present day valleys. The southeast-oriented Oak Creek tributary valleys eroded headward into the figure 5 map area first to capture the southeast and south-southeast oriented flood flow. Reversed flood flow in the north-northwest oriented Skull Creek valley to the east of figure 5 next captured southeast-oriented flood flow using the Bone Creek alignment and eroded the Skull Creek valley headward into the figure 5 map area. The northwest-oriented Skull Creek headwaters segment is evidence of a flood flow reversal. Next headward erosion of the north-oriented Skull Creek tributary valley in sections 29 and 32 beheaded flood flow to the newly eroded Skull Creek headwaters valley and a reversal of flood flow created the north-northwest oriented tributary headwaters. Finally headward erosion of the Platte River valley (north of figure 5) beheaded southeast-oriented flood flow moving on the Bone Creek alignment, caused a reversal of flood flow on that alignment and created the Bone Creek-Skull Creek drainage divide.

Detailed map of Skull Creek-Hunters Slough drainage divide area

Figure 6: Detailed map of Skull Creek-Hunters Slough drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 6 provides a detailed map of the Skull Creek-Hunters Slough drainage divide area seen in less detail in figure 4 above and is located east of the figure 5 map area (and includes overlap areas with figure 5). The east-northeast oriented Skull Creek headwaters valley is located in the figure 6 northeast quadrant (near the figure 6 north edge). The north-northwest oriented valley in section 6 (in the figure 6 north center area) is the south-southeast end of the north-northwest oriented Skull Creek valley seen in figures 3 and 4. Hunters Slough drainage flows in a northeast direction into that figure 6 valley and then makes a U-turn to flow in a south-southeast direction along the valley’s alignment to the figure 6 south edge. The valley in figure 6 is a well-defined north-northwest to south-southeast oriented through valley. The through valley was eroded as a south-southeast oriented flood flow channel moving south-southeast oriented flood water to what was then the newly eroded northeast-oriented Salt Creek valley further to the south (see figure 9 below). The Salt Creek valley had eroded headward from what was then the newly eroded Platte River-Wahoo Creek valley, which had eroded headward from the newly eroded Missouri River valley to capture the massive south-southeast oriented flood flow moving across Nebraska. South-southeast oriented flood flow moved in the through valley prior to headward erosion of the Platte River valley located north of figure 6. Headward erosion of the Platte River valley north of figure 6 beheaded the south-southeast oriented flood flow channel. Flood waters on the north end of the beheaded flood flow channel reversed flow direction to flow north-northwest to the newly eroded and deeper Platte River valley and created the present day Skull Creek-Hunters Slough drainage divide. Reversed flood flow in the Skull Creek valley captured yet to be beheaded southeast-oriented flood flow moving along the Bone Creek alignment. Northeast-oriented Skull Creek tributary valleys (and the northeast-oriented Hunters Slough headwaters valley) probably were eroded by yet to be beheaded southeast-oriented flood waters moving to the reversed flood flow in the newly reversed Skull Creek valley. The southeast-oriented stream in the figure 6 southwest quadrant is North Oak Creek. Note how shallow north-south through valleys link south-oriented North Oak Creek tributary valleys with headwaters of north-oriented Skull Creek valleys. The through valleys provide further evidence of south-oriented flood flow channels that once crossed the figure 6 map area prior to headward erosion of the east-oriented Platte River valley to the north of figure 6.

Wahoo Creek-Rock Creek drainage divide area

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

Figure 7 illustrates the Wahoo Creek-Rock Creek drainage divide area south and east of the figure 4 map area (the figure 4 southeast corner corresponds with the figure 7 northwest corner). Valparaiso is the town located in the figure 7 southwest quadrant. Touhy is the town located in the figure 7 west center. Weston is the town located along the figure 7 north center edge. Ceresco is the town located in the southeast quadrant. Oak Creek is the south-southeast oriented stream in the figure 7 southwest quadrant and continues in a south-southeast direction to join northeast-oriented Salt Creek at Lincoln (see figure 9). Rock Creek originates near Touhy and flows in an east and then in a southeast direction to the figure 7 south edge south of Ceresco and continues in a southeast direction to reach northeast-oriented Salt Creek (see figure 10). Wahoo Creek flows in a northeast direction to Weston and then east-southeast and east north-northeast along the figure 7 north edge (and north of figure 7 at Wahoo turns to flow in a southeast direction to join the Platte River near Ashland (see figure 2). Southeast-oriented Wahoo Creek headed toward the Platte River can just barely be seen in the figure 7 northeast corner. Miller Creek is a southeast and north oriented Wahoo Creek tributary located south of Weston. East-northeast and southeast oriented North Fork Rock Creek is located north of Ceresco and south of Swedeburg ( the small town located in the figure 7 east center area). Figure 7 drainage patterns can all be explained in the context of an immense southeast-oriented flood that initially flowed across the entire figure 7 map area on a topographic surface at least as high as the highest figure 7 elevations today. Headward erosion of what was then the deep northeast-oriented Salt Creek valley south of the figure 7 map area enabled the southeast-oriented Wahoo Creek and Rock Creek valleys and their tributary valleys to erode headward from the newly eroded Salt Creek valley north wall. At the same time the south-southeast oriented Oak Creek channel eroded headward from the deep Salt Creek north valley wall. The east-northeast oriented North Fork Rock Creek valley segment eroded headward from the southeast-oriented North Fork Rock Creek valley to capture southeast-oriented flood flow channels west of the newly eroded southeast-oriented North Fork valley. Headward erosion of the Wahoo Creek valley beheaded a major south-oriented flood flow route to the North Fork Rock Creek (see through valley northwest of Swedeburg) and flood waters on the north end of that beheaded flood flow route reversed flow direction to flow north to the newly eroded Wahoo Creek valley to create the north-oriented Miller Creek valley segment. Next the east-southeast oriented Miller Creek valley segment eroded west to capture southeast-oriented flood water moving to the newly eroded Rock Creek valley. The east- and northeast-oriented Wahoo Creek valley segments then eroded west and southeast from the newly eroded Wahoo Creek valley to capture southeast-oriented flood flow that was moving to the newly eroded Miller Creek and Rock Creek valleys. Evidence for southeast-oriented flood flow is not only found in present day valley orientations, but also in through valleys that cross present day drainage divides.

Detailed map of Wahoo Creek-Rock Creek drainage divide area near Touhy

Figure 8: Detailed map of Wahoo Creek-Rock Creek drainage divide area near Touhy.United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 8 provides a detailed map of the Wahoo Creek-Rock Creek drainage divide area seen in less detail in figure 7 above. Touhy is the small town located in the figure 8 west center area. Wahoo Creek originates near Touhy and flows in a north-northwest oriented valley (used by the railroad) to section 26 and then turns to flow in a northeast direction to the figure 8 north edge. Rock Creek originates just east of Touhy and flows east before turning to flow in a southeast direction to the figure 8 east edge (south half). The south-southeast oriented valley used by the railroad south of Touhy is drained by an Oak Creek tributary, which south of the figure 8 map area turns to flow in a southwest direction to join south-southeast oriented Oak Creek. Note how this south-southeast oriented Oak Creek tributary headwaters valley is linked by a through valley at Touhy with the north-northwest oriented Wahoo Creek headwaters valley. The north-northwest oriented Wahoo Creek headwaters valley was eroded by reversed flood flow on the north end of a beheaded south-southeast oriented flood flow channel moving flood water to the actively eroding Oak Creek channel and the newly eroded Salt Creek valley. Headward erosion of the northeast-oriented Wahoo Creek valley segment beheaded that south-southeast oriented flood flow route, causing flood waters on the north end to reverse flow direction and to create the present day Wahoo Creek-Oak Creek drainage divide at Touhy. Just north of Touhy in section 35 note several shallow northwest-southeast oriented through valleys eroded across the drainage divide between a north-northeast oriented Wahoo Creek tributary valley and the east-oriented Rock Creek headwaters valley. Those through valleys provide evidence of multiple south-southeast oriented flood flow channels that existed prior to headward erosion of the present day valleys. The Rock Creek valley eroded headward into the region first to capture the south-southeast oriented flood flow. Next headward erosion of the Wahoo Creek valley beheaded the south-southeast-oriented flood flow channels and the north-northeast oriented Wahoo Creek tributary valley was eroded by a reversal of flood flow. Interestingly, headward erosion of the Rock Creek valley did not capture south-southeast oriented flood flow in the through valley at Touhy. Probably headward erosion of the Wahoo Creek valley beheaded south-southeast oriented flood flow routes to the Rock Creek valley before the Rock Creek valley could erode further to the west. Close study of the figure 8 map area reveals many other shallow through valleys eroded across the Wahoo Creek-Rock Creek drainage divide.

Oak Creek and Salt Creek valleys near Lincoln

Figure 9: Oak Creek and Salt Creek valleys near Lincoln.United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 illustrates the Oak Creek and Salt Creek valleys near Lincoln. Lincoln is the city located along the figure 9 south edge. Oak Creek flows in a south-southeast direction from the figure 9 northwest corner to the Municipal Airport area in the figure 9 southwest corner. Oak Creek appears to have been moved so as to flow around the airport, but it does join northeast-oriented Salt Creek near West Lincoln. Salt Creek flows in a northeast direction from the figure 9 southwest corner to the figure 9 northeast corner and continues beyond the figure 9 map area in a northeast direction to join southeast-oriented Wahoo Creek near Ashland. Waverly is the small town located in the figure 9 northeast corner. Note other southeast and south-southeast oriented Salt Creek tributaries and also the northwest and north-northwest oriented Salt Creek tributaries. The tributary orientations provide evidence the Salt Creek valley eroded headward across multiple southeast and/or south-southeast oriented flood flow channels, such as might be found in a southeast or south-southeast oriented anastomosing channel complex. The southeast and south-southeast oriented tributary valleys eroded headward along the flood flow channels from the newly eroded and what was the deep northeast-oriented Salt Creek north valley wall. The northwest and north-northwest oriented tributary valleys were eroded by reversals of flood flow on the north ends of beheaded southeast and south-southeast oriented flood flow channels.  Flood waters on the north ends of those reversed flood flow channels reversed flow direction to eroded the north-oriented Salt Creek tributary valleys. Remember, the Salt Creek valley eroded headward and beheaded the south-southeast and southeast oriented flood flow channels one channel at a time. Also, remember the flood flow channels were anastomosing or interconnected. This meant reversed flood flow on a newly beheaded flood flow channel could capture yet to be beheaded flood flow from adjacent yet to be beheaded flood flow channels further to the west. Such captures of yet to be beheaded flood flow provided quantities of flood waters required to erode significant northwest and north-northwest oriented valleys.

Mosquito Creek-Robinson Branch drainage divide area

Figure 10: Mosquito Creek-Robinson Branch drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the Mosquito Creek-Robinson Branch drainage divide area located north and east of the figure 9 map area. The south-southeast oriented Platte River can be seen in the figure 10 northeast corner. Ashland is the town located in the figure 10 east center area. Greenwood is the town located along the figure 10 south center edge and Memphis is the smaller town located in the figure 10 northeast quadrant near the north edge. Southeast-oriented Wahoo Creek flows from Memphis to join the Platte River just east of the figure 10 map area. Mosquito Creek is the east-northeast oriented Wahoo Creek tributary flowing to the Wahoo Creek valley near Memphis. Northeast-oriented Salt Creek flows from Greenwood to join southeast-oriented Wahoo Creek near Ashland. The North Fork Rock Creek flows in a southeast direction from the figure 10 northwest corner to join east-oriented Rock Creek and then to join northeast-oriented Salt Creek south of the figure 10 map area. Southeast-oriented Robinson Creek flows across the figure 10 center area to join northeast-oriented Salt Creek north of Greenwood. Note northwest-oriented Greenwood Creek and Callahan Creek flowing to northeast-oriented Salt Creek (Greenwood Creek is northwest-oriented south of the figure 10 map area). What has happened here is southeast-oriented flood water initially flowed across the entire figure 10 map area on a topographic surface at least as high as the highest figure 10 elevations today. The deep Platte River valley eroded headward into the figure 10 map area (from what was then the newly eroded Missouri River valley to the east) to capture the southeast-oriented flood flow. The Platte River then eroded headward along a major south-southeast oriented flood flow channel. At the same time the southeast oriented Wahoo Creek valley eroded headward and the northeast-oriented Salt Creek valley eroded to the southwest to capture southeast-oriented flood flow west of the actively eroding Platte River valley. Southeast and south-southeast oriented Salt Creek tributary valleys eroded headward along southeast-oriented flood flow channels from the newly eroded Salt Creek valley north wall. The east-northeast oriented Mosquito Creek valley eroded headward from the newly eroded Wahoo Creek valley to capture southeast-oriented flood flow that was moving to the actively eroding southeast-oriented Robinson Branch valley. Northwest-oriented Salt Creek tributary valleys were eroded by reversals of flood flow along the north ends of the beheaded flood flow channels.

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.