A geomorphic history based on topographic map evidence

The southeast-oriented Cedar River and North Loup River valleys in Valley, Greeley, and adjacent counties drain to the northeast-oriented Loup River, which flows along the north edge of the large northeast-oriented Platte River valley. Topographic map evidence demonstrates the southeast-oriented Loup River tributary valleys and their tributary valleys in this Cedar River-North Loup River drainage divide area were eroded headward by an immense southeast-oriented flood, which converged with a massive northeast-oriented flood in the Platte River valley area. Drainage orientations, anastomosing channel complexes, and through valleys across drainage divides are some of the evidence supporting this interpretation. Convergence of two large-scale floods in Nebraska probably resulted in ponding of flood waters, which probably affected much larger regions than this drainage divide area. Flood waters probably have eroded some of the flood deposited sediments. Sand dunes have formed on what were probably flood deposited deltaic sediments.

• The purpose of this essay is to use topographic map interpretation methods to explore Cedar River-North Loup River drainage divide area landform origins in Valley, Greeley and adjacent 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 Cedar River-North Loup River drainage divide area landform origins in Valley, Greeley, and adjacent 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.

Cedar River-North Loup River drainage divide area location map

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

Figure 1 provides a location map for the Cedar River-North Loup River drainage divide area in Valley, Greeley, and adjacent counties, Nebraska. The Missouri River flows in an east-southeast direction from the figure 1 north center edge to Sioux City and then in a south-southeast direction to Omaha, located near the figure 1 east edge. A large area in eastern Nebraska occupies most of the figure 1 map area with a small area in northwestern Iowa located east of the Big Sioux River and Missouri River in the figure 1 northeast area and a small area of southeast South Dakota located north of the Missouri River and west of the Big Sioux River. The Platte River flows in a southeast direction from North Platte (near the figure 1 west edge) to Kearney and then northeast to Columbus and Fremont before turning to flow south and east to flow to the south-southeast oriented Missouri River. The Loup River is located north of the northeast-oriented Platte River segment and joins the Platte River near Columbus. Major Loup River tributaries are southeast-oriented and from east to west area, Beaver Creek, which flows through Albion and St Edward to join the Loup River near Genoa; Cedar River (unlabeled on figure 1), which flows through Ericson and Cedar Rapids to join the Loup River near Fullerton; North Loup River, which flows through Brewster, Burwell, Ord, North Loup, and Elba; Middle Loup River, which flows through Thedford, Dunning, Arcadia, and Loup City to join the Loup River near Boelus; and the South Loup River, which flows through Stapleton, Arnold, and Calloway before turning to flow in a northeast direction at Pleasanton. Longer Loup River tributaries originate in the Nebraska Sand Hills region (area labeled “HILLS” on figure 1) and flow in a southeast direction through what is commonly considered to be a loess covered region. North of the Loup River drainage basin in the east is the southeast-oriented Elkhorn River drainage basin and further to the west is the east-oriented Niobrara River drainage basin. This essay focuses on the Cedar River-North Loup drainage divide area, located east of the North Loup River (downstream from Burwell) and west of the Cedar River (downstream from Spalding). Further northwest the North Loup River and the Cedar River headwaters are located in the Sand Hills region. The Beaver Creek-Cedar River drainage divide area between the South Fork Elkhorn River and Loup River essay describes the region located east of the present study area and the Elkhorn River-North Loup River drainage divide area in Rock, Holt, and Garfield Counties describes the region located north of the this study area and can be found under Loup River or Elkhorn River on the sidebar category list. Additional essays describing regions north and east of the present study area can be found in under Niobrara River and Platte River (NE) on the sidebar category list.

Cedar River-North Loup River drainage divide area detailed location map

Figure 2: Cedar River-North Loup 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 Cedar River-North Loup River drainage divide area in Valley, Greeley, and adjacent counties. Loup, Garfield, Wheeler, Valley, Greeley, Boone, Nance, Sherman, Howard, and Merrick are Nebraska county names and the county boundaries are shown. The northeast oriented Platte River can just barely be seen along the Merrick County southeast border in the figure 2 southeast corner. The Cedar River originates near Ericson in the southwest corner of Wheeler at the confluence of southeast oriented Big Cedar Creek and Dry Cedar Creek. From Ericson the Cedar River flows across the Greeley County northeast corner, Boone County southwest corner, and into Nance County where it joins the Loup River near Genoa. Cedar River tributaries of importance in this discussion are Dry Cedar Creek in southeast Garfield County, Freeman Creek in northeast Greeley County, and the North and South Branches of Timber Creek, which flows to Cedar River in northwest Nance County. The North Loup River flows in a southeast direction across Loup County to Burwell in the Garfield County southwest corner. From Burwell the North Loup River flows in southeast direction across Valley County and the Greeley County southwest corner to Elba in Howard County. At Elba the North Loup River turns to flow to join the northeast oriented Loup River south of Cushing. The southeast and south oriented stream originating north of Greeley in Greeley County and joining the Loup River near Cushing is Spring Creek. Note how with the exception of the Loup River and Platte River area in the figure 2 southeast corner almost all figure 2 drainage routes are southeast-oriented. This predominance of southeast-oriented drainage routes is interpreted to have resulted from a massive southeast-oriented flood, which flowed across the entire figure 2 map area. Other Missouri River drainage basin landform origins research project essays published on this website have demonstrated the flood waters can be traced headward in a northwest direction from Nebraska to north central Montana and southern Alberta. Note in the figure 2 southeast corner how there are multiple northeast oriented streams or rivers flowing roughly parallel to each other. This region is interpreted here to be where a large northeast and east oriented valley containing an anastomosing channel complex developed as a massive southeast-oriented flood from the northwest converged with an immense northeast- and east-oriented flood from the west. Flood waters from the northwest, once they entered this northeast-oriented valley, were forced by flood waters from the west to flow along the valley’s north edge, which explains why the Loup River valley is today located along the north edge of the large northeast-oriented Platte River valley.

Timber Creek-Loup River drainage divide area

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

Figure 3 illustrates the Timber Creek-Loup River drainage divide area west of Fullerton. The Loup River flows in a northeast direction in the figure 3 southwest quadrant. The Cedar River flows in a south and southeast direction from the figure 3 north edge to join the Loup River just east of the figure 3 map area near Fullerton. Timber Creek flows in an east and southeast direction from the figure 3 northwest corner area to join the Cedar River northwest from Fullerton. North Star is the small community located near the figure 3 center. The larger south and south-southeast oriented stream west of North Star is Horse Creek, which joins the Loup River south of the figure 3 map area. Note how the figure 3 drainage divide areas appear to be fairly level erosion surfaces. These erosion surfaces were probably formed by southeast-oriented flood water moving across the figure 3 region prior to headward erosion of what was then the deep northeast oriented Loup River valley (and parallel Platte River valley to the southeast). Headward erosion of the deep Loup River valley lowered base level and deep southeast-oriented valleys began to erode headward along the southeast-oriented flood flow routes. Some of these valleys were able to erode headward faster than others and were able to behead southeast-oriented flood flow routes to other southeast-oriented valleys. For example, the Timber Creek valley eroded headward to behead southeast-oriented flood flow to what was then the newly eroded Horse Creek valley. The Loup River in figure 3 is flowing along the north edge of what is a broad northeast oriented Platte River valley. The northeast-oriented Platte River channel, which is flowing near the valley center, is almost 20 kilometers to the southeast. Why do the Loup River and Platte River flow parallel to each other in this large valley rather than joining to become one northeast-oriented river? The parallel channels are evidence that two immense floods converged in Nebraska at the time the northeast- and east-oriented Platte River valley eroded headward across the state. One flood came from the northwest while the other flood was from the west. Prior to headward erosion of what was then the deep Platte River valley there probably was considerable ponding of flood waters, with deltaic sediments being deposited further to the west and north and finer grained silts probably being deposited to the east and perhaps in the figure 3 map area (and other map areas illustrated in this essay). Once the deep Platte River-Loup River valley eroded headward across the region flood waters drained from the region and deep tributary valleys eroded to the northwest. However, flood waters from the northwest flowing into the newly eroded Platte River valley had to flow along the valley’s north edge because further to the southeast the valley was filled with large volumes of flood waters from the west.

Spring Creek-Timber Creek drainage divide area

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

Figure 4 illustrates the Spring Creek-Timber Creek drainage divide area and the Timber Creek headwaters area northwest of the figure 3 map area. The Cedar River flows in a southeast direction across the figure 4 northeast corner. The town of Cedar Rapids is located along the Cedar River just east of the figure 4 map area. The North Branch Timber Creek flows in a southeast direction to the figure 4 southeast corner and originates along the Greeley County-Boone County border area in the figure 4 north center area. The South Branch Timber Creek flows in a south-southeast direction almost to the figure 4 south center edge and then jogs northeast before flowing southeast to the figure 4 south edge and to join the southeast-oriented North Branch south of the figure 4 map area. West of the south-southeast oriented South Branch Timber Creek near the figure 4 west edge (south half) is south-southeast oriented East Branch Spring Creek. North-northeast drainage in the figure 4 northwest quadrant is flowing to east-oriented Freeman Creek (see figure 5 below), which is a Cedar River tributary. Note how the south-southeast oriented East Branch Spring Creek valley has beheaded southeast-oriented flood routes to the South Branch Timber Creek headwaters area. A close look at the drainage divide reveals through valleys, which provide evidence of flood flow routes to what was then the actively eroding South Branch Timber Creek valley prior to headward erosion of the East Branch Spring Creek valley. Also note how the north-northeast oriented Freeman Creek tributary valley has beheaded southeast-oriented flood flow routes to the North Branch Timber Creek headwaters. Again there are through valleys linking the north-northeast oriented Freeman Creek tributary valley with the southeast-oriented North Branch Timber Creek headwaters valleys. The size of the East Branch Spring Creek valley (better seen in figure 5 below) and the north-northeast oriented Freeman Creek tributary valley suggest the figure 4 region is underlain by easily eroded material, which flood waters were able to easily flush out of the region as flood waters eroded the region. The north-northeast oriented Freeman Creek tributary valley probably formed as a reversal of flood flow when headward erosion of the east-oriented Freeman Creek valley beheaded southeast-oriented flood flow routes. Flood waters on the north ends of the beheaded southeast-oriented flood flow routes reversed flow direction to flow north to the newly eroded and deeper Freeman Creek valley.

Spring Creek-Freeman Creek drainage divide area

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

Figure 5 illustrates the Spring Creek-Freeman Creek drainage divide area west and north of the figure 4 map area and includes overlap areas with figure 4. Greeley is the town located in the northeast corner of the figure 5 southwest quadrant. Belfast is the much smaller town in the figure 5 northwest corner and O’Connor is the smaller town located near the figure 5 south edge (east of the center area). Spring Creek originates south of Belfast and flows in a southeast direction to Greeley and O’Connor before flowing to the figure 5 south edge. As noted in the figure 2 discussion Spring Creek flows directly to the northeast-oriented Loup River. Freeman Creek flows east in the figure 5 northeast quadrant (near the north edge) and is a Cedar River tributary. South-southeast oriented South Branch Timber Creek headwaters are located in the figure 5 southeast corner. The East Branch Spring Creek flows in southeast and south-southeast direction to join Spring Creek just east of O’Connor near the figure 5 south edge.The West Branch Spring Creek flows in a southeast direction in the Boston Valley area located southwest of Greeley. The Spring Creek drainage basin in this figure 5 map area is a maze of anastomosing channels and provides evidence the region was eroded by a large south-southeast oriented flood. Prior to headward erosion of the Spring Creek valley flood waters were flowing southeast to what was then the actively eroding Timber Creek valley system. At that time flood waters were flowing on a topographic surface at least high as the highest figure 5 elevations today. Headward erosion of the southeast-oriented Cedar River valley and its east-oriented Freeman Creek tributary valley beheaded southeast-oriented flood flow to the actively North Branch Timber Creek valley and caused a significant reversal of flood flow to erode the large north-northeast oriented Freeman Creek tributary valley. At the same time the deep Spring Creek valley eroded headward into the figure 5 map area and appears to have rapidly drained flood waters and easily eroded sediments from the region, especially in the region between Spring Creek and East Spring Creek. Streamlined hills are erosional residuals between south-southeast oriented flood flow channels.

Spring Creek-North Loup River drainage divide area

Figure 6: Spring Creek-North Loup River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Spring Creek-North Loup River drainage divide area south and west of the figure 5 map area and includes overlap areas with figure 5. Greeley is located near the figure 6 north edge. Spring Creek flows southeast and east from the Greeley area to O’Connor (southeast from Greeley) and to join the south-southeast oriented East Branch Spring Creek. The West Branch Spring Creek flows in a southeast direction from the Boston Valley area (southwest from Greeley) to the figure 6 southeast corner. Wallace Creek flows in a south direction from north of Horace (in the figure 6 northwest corner) to join the North Loup River near Scotia (located near the figure 6 west edge). Fish Creek is the south-oriented stream located east of south-oriented Wallace Creek. Note how the Wallace Creek drainage basin looks like funnel, suggesting flood waters flood waters flushed large amounts of easily eroded sediment from that drainage basin. A similar flushing action is suggested for the Spring Creek drainage basin and the north-northeast oriented Freeman Creek tributary valley seen in figure 5. This flushing action suggests the region was/is covered with easily eroded material (possibly material that when it gets wet it can be easily moved). Again, prior to headward erosion of the present day deeper valleys flood waters flowed across the entire figure 6 map area on a topographic surface at least as high as the highest figure 6 elevations today. The Spring Creek valley eroded headward first and apparently began to rapidly capture flood flow as flood waters rapidly eroded the easily eroded underlying sediment. Headward erosion of the West Branch Spring Creek valley captured some of the south-oriented flood flow before being beheaded by headward erosion of the Spring Creek valley (figure 7 below provides a detailed map of the Spring Creek-West Branch Spring Creek drainage divide south of Greeley). At about the same time headward erosion of the North Loup River valley-Fish Creek valley entered the region and soon thereafter the Wallace Creek valley eroded north and beheaded southeast-oriented flood flow to the newly eroded Fish Creek valley. Headward erosion of the Wallace Creek valley flushed out considerable sediment west of the Spring Creek drainage basin. It is possible there were flood waters still ponded further to the north and northwest and this flushing action occurred as those ponded flood waters rapidly flowed from the region.

Detailed map of Spring Creek-West Branch Spring Creek drainage divide area

Figure 7: Detailed map of Spring Creek-West Branch Spring 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 Spring Creek-West Branch Spring Creek drainage divide area south of Greeley seen in less detail in figure 6 above. Spring Creek flows south from the figure 7 north center edge and then turns to flow east and east-southeast to the figure 7 east edge. The West Branch Spring Creek flows in a southeast, south, and east-southeast direction from the Boston Valley area near the figure 7 west edge to the figure 7 south center edge. Figure 7 illustrates numerous north-south oriented through valleys linking the Spring Creek valley with the West Branch Spring Creek valley. The deepest of the through valleys are located in the figure 7 center area and are used by the north-south railroad line (now abandoned) and by the north-south road immediately east of the railroad line. Those through valleys are approximately 100 feet deep and link a north-oriented Spring Creek tributary with south-oriented West Branch Spring Creek tributary. Those valleys plus the numerous other north-south oriented through valleys in figure 7 provide evidence that prior to headward erosion of the present day Spring Creek valley multiple south-oriented channels moved flood water from the present day Spring Creek drainage basin to what was at one time the actively eroding West Branch Spring Creek valley. These multiple north-south oriented valleys suggest the presence of a south-oriented anastomosing channel complex. The anastomosing channel complex hypothesis is supported by the existence of an anastomosing channel complex eroded into the Spring Creek drainage basin floor north of the figure 7 map area (see figure 5). An anastomosing channel complex provides evidence the region was eroded by a large south-oriented flood and existence of through valleys at different elevations suggests flood waters originally flowed across a topographic surface at least as high as the highest figure 7 elevations today. Headward erosion of the West Branch Spring Creek valley first captured south-oriented flood water and diverted the captured water southeast. Next headward erosion of the Spring Creek valley beheaded the south-oriented flood flow channels to the newly eroded West Branch Spring Creek valley. Flood waters on north ends of beheaded flood flow channels reversed flow direction to flow north to the newly eroded Spring Creek valley. These reversed flood flow channels account for present day north-oriented Spring Creek tributary valleys.

Dry Cedar Creek-North Loup River drainage divide area

Figure 8: Dry Cedar Creek-North Loup River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Dry Cedar Creek-North-Loup River drainage divide north and west of the figure 6 map area. Ord is the town located in the figure 8 southwest corner. The North Loup River flows in a southeast direction across the figure 8 southwest corner. Southeast-oriented Dry Cedar Creek is located north of the figure 8 northeast quadrant (see figures 9a and 10 below) and flows to the join southeast-oriented Big Cedar Creek at Ericson and to form the southeast-oriented Cedar River (see figures 1 and 2). Headwaters of south-oriented Wallace Creek are located in the figure 8 southeast corner. East of the figure 8 southeast quadrant are headwaters of south-oriented Spring Creek and East Branch Spring Creek seen in figure 5 (Belfast seen in the figure 5 northwest corner is almost directly east of Ord and is just east of the figure 8 map area). Note how multiple south-oriented North Loup River tributary valleys have eroded headward into the higher region northeast of the southeast-oriented North Loup River valley. Through valleys link these south-oriented North Loup River tributary valleys with a large southeast-oriented flood eroded valley occupying the figure 8 northeast region. The southwest-wall of that flood eroded valley appears as northwest-southeast oriented escarpment. Figure 9 below provides a more detailed of the region where the north and northeast oriented highway from Ord crosses that northwest-southeast oriented flood eroded valley wall. The south-oriented stream originating in that through valley is Elm Creek and a close look at figure 8 reveals Elm Creek has northwest-oriented headwaters. Today the floor of that large southeast-oriented valley is covered with dunes, suggesting the valley floor is covered by sand and/or silt. The multiple south-oriented North Loup River tributaries valleys and the through valleys linking those south-oriented tributary valleys with the large southeast-oriented valley provide evidence large volumes of water once flowed south from that large southeast-oriented valley to what was then the newly eroded southeast-oriented North Loup River valley, probably prior to headward erosion of the large southeast-oriented valley. As seen in figures below the large southeast-oriented valley south of the southeast-oriented Dry Cedar Creek valley apparently was partially drained by the Wallace Creek and Spring Creek valleys. Large volumes of sediment were removed from this large valley, suggesting whatever covered this figure 8 map area was easily eroded and easily transported.

Detailed map of Dry Cedar Creek-North Loup River drainage divide area

Figure 9: Detailed map of Dry Cedar Creek-North Loup River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a detailed map of the Dry Cedar Creek-North Loup River drainage divide area seen in less detail in figure 8 above. The southwest valley wall of the large northwest-southeast oriented valley seen in figure 8 above extends in a northwest-southeast direction across the figure 9 map area. Hills southwest of the large southeast-oriented valley wall are more than 100 feet higher in elevation than the floor of the large southeast-oriented valley to the northeast. Note how Elm Creek headwaters begin in section 22 and flow in a northwest direction before turning to flow southwest in section 21. Also, in section 16 there are northwest-oriented headwaters for a south-oriented Elm Creek tributary (flowing south in near the section 17 east border). These northwest-oriented headwaters are evidence headward erosion of the southwest and south oriented Elm Creek valley beheaded southeast-oriented flood water in the larger southeast-oriented valley and the southeast-oriented flood water was moving at an elevation much higher than the present day elevations in the figure 9 northeast quadrant. Flood flow on the northwest ends of the beheaded flood flow routes reversed flow direction to flow northwest to the newly eroded southwest and south oriented valleys. Note how the northwest-oriented Elm Creek headwaters flow in a shallow valley eroded along the edge of the much larger southeast-oriented valley wall and not on the larger valley floor. These northwest-oriented Elm Creek headwaters provide evidence the large southeast-oriented valley was still being eroded at the time the Elm Creek valley eroded headward into the figure 9 map area. However, the failure of the south-oriented Elm Creek valley to erode a deeper valley suggests the larger southeast-oriented valley drained primarily in other directions (i.e. to the Wallace Creek. Spring Creek, and Cedar River valleys).

• Figure 9a below uses reduced size maps to provide a big picture view of the Cedar River-North Loup River drainage divide area east of Ord. Ord is located on the figure 9a west edge and Spalding is located near the figure 9a east edge. Greeley is in the figure 9a southeast quadrant near the figure 9a south edge. Ericson is located near the figure 9a north center edge. Big Cedar Creek flows in a south-southeast direction from the figure 9a north center edge to join southeast-oriented Dry Cedar Creek at Ericson and then to flow as the Cedar River to Spalding and the figure 9a east edge. The southeast-oriented North Loup River is located in the figure 9a southwest quadrant. East-oriented Freeman Creek can be seen flowing to join the Cedar River just east of the figure 9a map area. The south-southeast oriented Spring Creek drainage basin can be seen in the Greeley area and the south-oriented Wallace Creek drainage basin is located between the Spring Creek drainage basin and the North Loup River valley. Elevations decease to the south and the region northeast of the northwest-southeast oriented valley wall seen in figures 8 and 9 is higher in elevation than the highest elevations in the Spring Creek and Timber Creek drainage basins to the south. In other words, the large southeast-oriented through valley was probably eroded at a time prior to headward erosion of the deep northeast-oriented Loup River valley (south of the figure 9a map area). Headward erosion of the deep Cedar River, Timber Creek, Spring Creek, and North Loup River valleys probably occurred very late in region’s erosion history. Most sediments eroded from the region northeast of the northwest-southeast oriented valley wall was carried by flood waters to points southeast of the present day northeast-oriented Loup River valley.

Figure 9a: Big picture view of Cedar River-North Loup River drainage divide area east from Ord. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Big Cedar Creek-Dry Cedar Creek drainage divide area

Figure 10 illustrates the Big Cedar Creek-Dry Cedar Creek drainage divide area north and west of the figure 9a map area. The North Loup River is located in the figure 10 southwest corner and flows northeast to join the southeast oriented Calamus River and then flows southeast to the figure 10 south edge. The reservoir located along the figure 10 west edge is Calamus Reservoir and is located on the Calamus River. Burwell is the town located in the figure 10 southwest quadrant. Big Cedar Creek flows in an east-southeast and southeast direction from the figure 10 north center edge area to join southeast oriented Dry Cedar Creek near the figure 10 southeast corner. Dry Cedar Creek flows from the figure 10 center area to join Big Cedar Creek near Ericson in the figure 10 southeast corner (and to form the southeast-oriented Cedar River, which flows in a southeast direction from the figure 10 map area). Little Cedar Creek is the southeast- and east-oriented Big Cedar Creek tributary in the figure 10 north center area. The northwest end of the northwest-southeast oriented valley wall seen in figures 8, 9, and 9a above is located in the figure 10 south center area. Note how the Little Cedar Creek and Big Cedar Creek valleys have eroded west-northwest in the figure 10 north center area probably to behead southeast-oriented flood flow routes that were moving flood water to what was then the actively eroding Dry Cedar Creek valley. Sand dunes appear to cover most of the figure 10 map area. These dunes suggest the region is covered by flood deposited silts and/or sands that subsequent wind action has been able to move and deposit as dunes. The sand dunes obscure much of the figure 10 flood eroded drainage channels and prevent a more detailed topographic map analysis than is possible from the surface drainage routes seen today. As previously noted the northwest-southeast oriented valley wall provides evidence that southeast-oriented flood waters removed significant amounts of material from the region northeast of that valley wall. Probably the entire region northeast of that valley wall was covered by whatever material forms the hills southwest of the valley wall. The fact the material was removed suggests it is easily eroded material and it could even be sediments deposited during still earlier flood stages. The presence of silts and/or sand covering the region suggests at least some of the flood deposited sediments still remain. Most of the sediment removal occurred before headward erosion of the northeast-oriented Loup River valley and was carried by flood waters further to the southeast and perhaps all the way to the Gulf of Mexico.

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.