Elkhorn River-Loup River drainage divide area landform origins in Rock, Holt, and Garfield Counties, Nebraska, USA

· Elkhorn River, Loup River, Nebraska
Authors

A geomorphic history based on topographic map evidence

Abstract:

The Elkhorn River-Loup River drainage divide area in Rock, Holt, and Garfield Counties, Nebraska was eroded by a massive southeast-oriented flood, which also deposited deltaic sediments in the region. Subsequent eolian activity has created sand dunes and otherwise obscured the regional drainage history, although present day drainage routes support the flood origin interpretation. Prior to headward erosion of the Elkhorn River valley southeast-oriented flood waters were moving to the northeast-oriented Loup River valley and were eroding southeast-oriented Loup River tributary valleys headward into the present day drainage divide area. Headward erosion of the Elkhorn River valley and various Elkhorn River tributary valleys in an identifiable sequence beheaded southeast-oriented flood flow to what was then the actively eroding southeast-oriented Loup River tributary valleys.

Preface:

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

Introduction:

  • The purpose of this essay is to use topographic map interpretation methods to explore Elkhorn River-Loup River drainage divide area landform origins in Rock, Holt, and Garfield 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-Loup River drainage divide area landform origins in Rock, Holt, and Garfield 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-Loup River drainage divide area location map

Figure 1: Elkhorn River-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 is a location map for the Elkhorn River-Loup River drainage divide area in Rock, Holt, and Garfield Counties. With the exception of a small area in the northeast corner area figure 1 provides a map of a large area in the state of Nebraska. Immediately north of Nebraska is South Dakota, which is the state seen in the figure 1 northeast corner. The east and southeast oriented Missouri River forms the South Dakota-Nebraska border in the figure 1 northeast corner area. The Platte River flows across the figure 1 south half and flows in a southeast direction from North Platte (in the figure 1 southwest quadrant( to Kearney and then in a northeast direction to Columbus and North Bend. East of the figure 1 map area the Platte River turns to flow in a south and then east direction to join the south-southeast oriented Missouri River. Flowing in an east direction across the figure 1 north edge area is the Niobrara River, which joins the Missouri River near Niobrara, Nebraska (in figure 1 northeast quadrant). The Elkhorn River originates near Basset (located in the figure 1 north center) and flows southeast and then northeast to Stuart. From Stuart the Elkhorn River flows in a southeast direction to Norfolk and Stanton, where the Elkhorn River makes a northeast jog before flowing southeast to the figure 1 east edge. The North Loup River originates west of the figure 1 map area and flows east and southeast to Brownlee and then southeast to Brewster, Taylor, Burwell, Ord, North Loup, Cotesfield, and Elba before joining the northeast-oriented Loup River, which joins the Platte River near Columbus. The Calamus River is a North Loup River tributary, which originates at Moon Lake (in the figure 1 northwest quadrant) and flows in a southeast direction to join the North Loup River near Burwell. Cedar River is an unlabeled stream originating north of Burwell and flowing in a southeast direction to Ericson, Spalding, Cedar Rapids, and Belgrade before joining the northeast-oriented Loup River near Fullerton. Beaver Creek is a labeled stream immediately east of Cedar River and flows in a southeast direction to Albion and St Edward and joins the Loup River near Genoa. This essay addresses the region between the Elkhorn River headwaters and the southeast-oriented Calamus River and southeast-oriented Cedar River. Additional essays describing evidence near the Elkhorn River-Loup drainage divide area illustrated and discussed here can be found under Loup River, Elkhorn River, or Niobrara River on the sidebar category list.

Elkhorn River-Loup River drainage divide area detailed location map

Figure 2: Elkhorn River-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 map of the Elkhorn River-Loup River drainage divide area in Rock, Holt, and Garfield Counties. Rock, Holt, Antelope, Loup, Garfield, Wheeler, and Boone are Nebraska county names and the county boundaries are shown. The Elkhorn River originates south of Bassett in Rock County (figure 1 northwest corner area) and flows southeast and northeast to near Stuart in western Holt County (near figure 1 north edge). From Stuart the Elkhorn River flows in a southeast direction across Holt County into and across Antelope County to the figure 2 east edge. Elkhorn River tributaries of importance in the maps and discussions below include the North Branch, which originates near Bassett and flows east to join the Elkhorn River near Stuart; Keegan Creek, which flows in a northeast direction to join the Elkhorn River southeast from Stuart; Holt Creek, which flows in an east and northeast direction to join the Elkhorn River near Emmet; Dry Creek, which flows in a northeast direction to join the Elkhorn River near O’Niel; the South Fork Elkhorn River, which flows in an east direction to join the Elkhorn River near Ewing; Cache Creek, which flows in a northeast direction to join the Elkhorn River southeast from Ewing; and Clearwater Creek, which flows in an east and northeast direction to join the Elkhorn River near Clearwater. Note how Beaver Creek originates in northeast Wheeler County south of the Clearwater Creek headwaters and flows in a southeast direction into Boone County and joins the Loup River southeast from the figure 2 map area. Note also that Cedar River headwaters include Big Cedar Creek, which originates in northern Garfield County just south of the South Fork Elkhorn River headwaters, and flows in a southeast direction to become the southeast-oriented Cedar River and to join the Loup River south of the figure 2 map area. Further note southeast-oriented Calamus River tributaries originating in southern Rock County, including Gracie Creek, Bloody Creek, and Skull Creek. These southeast-oriented Calamus River tributaries originate south of the Elkhorn River headwaters, located further north in Rock County. West of Rock County in the figure 2 northwest corner are headwaters of north-oriented Long Pine Creek, which flows to the east-oriented Niobrara River north of the figure 2 map area. In other words, west of the Elkhorn River headwaters area there is no east-oriented river between the east-oriented Niobrara River north of the figure 2 map area and the southeast-oriented Calamus River (see figure 1). The Niobrara River-North Loup River drainage divide area essay describes the region located west of the Elkhorn River headwaters. Hundreds of Missouri River drainage basin landform origins research project essays published on this website have established a strong case for an immense southeast-oriented flood that moved across the present day Niobrara River drainage basin into the present day Elkhorn River drainage basin. Prior to headward erosion of the Niobrara and Elkhorn River valleys these southeast-oriented flood waters flowed southeast to what was then probably an actively eroding Loup River drainage basin.

North Branch-Elkhorn River drainage divide area

Figure 3: North Branch-Elkhorn River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the North Branch Elkhorn River-Elkhorn River drainage divide area east and southeast of Bassett. Bassett is the town located on the figure 3 west edge. The Elkhorn River originates in the figure 3 southwest quadrant and flows in a southeast direction to the figure 3 south center area and then turns to flow in a northeast direction to the figure 3 east edge. Dry Creek is a southeast, northeast, north-northwest, northeast, and north oriented Elkhorn River located in the figure 3 southeast quadrant. The North Branch Elkhorn River originates in the figure 3 northwest quadrant and flows in an east-oriented direction to the figure 3 northeast corner. From limited evidence available in figure 3 it is possible to suggest headward erosion of present day valleys occurred during a large southeast-oriented flood. As the northeast-oriented Elkhorn River began to erode headward into the figure 3 map area the Dry Creek valley eroded south and southwest and beheaded a south-southeast-oriented flood flow route, which reversed flow direction to flow north-northwest. The Dry Creek valley then eroded southwest from that newly reversed north-northwest flood flow route to capture a southeast-oriented flow route, which was soon thereafter beheaded by Elkhorn River valley headward erosion. The northeast-oriented Elkhorn River valley then eroded headward or to the southwest into the figure 3 map area to capture southeast-oriented flood flow and beheaded the Dry Creek headwaters and then eroded further to capture the southeast-oriented Elkhorn River headwaters. The North Branch Elkhorn River valley then eroded west to behead southeast-oriented flood flow to the newly eroded Elkhorn River valley. The figure 3 map area is on the northeast margin of the Nebraska Sand Hills region and south of the Elkhorn River are sand dunes. The figure 3 map area appears to be remarkably level and much of the map area lacks an integrated drainage pattern. A possible explanation for the lack of drainage routes is soils are sandy and wind-blown sand has filled intermittent drainage channels. If so, the sand origin is of interest. From figure 3 map evidence alone it is impossible to suggest a sand origin. However, using evidence illustrated in essays written for drainage basins located north and northwest of the figure 3 map area (e.g. essays listed under Niobrara River, White River, and Cheyenne River on the sidebar category list) it is possible to suggest the sand was transported to the figure 3 map region by immense southeast-oriented floods. If flood waters were temporarily ponded in this figure 3 region sediment being carried by the southeast-oriented flood waters would probably have been deposited. Subsequent wind action has since created dunes and spread sand deposits across the region, which obscures drainage routes required to work out drainage histories.

Elkhorn River-Keegan Creek drainage divide area

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

Figure 4 illustrates the Elkhorn River-Keegan Creek drainage divide area east of the figure 3 map area and includes a significant overlap area with figure 3. The north-south Rock-Holt County border is located slightly west of the figure 4 center. Stuart is the town in Holt County (figure 4 northeast quadrant). The North Branch Elkhorn River flows across the figure 4 northwest quadrant in an east direction to join the northeast-oriented Elkhorn River in the figure 4 north center just northwest from Stuart. The Elkhorn River turns from flowing southeast to flowing northeast in the figure 4 southwest corner area and flows to join the east-oriented North Branch just northwest of Stuart. From the Stuart area the Elkhorn River flows in a southeast direction to the figure 4 east center edge. Dry Creek can be seen flowing in a southeast, northeast, north-northwest, northeast, and north direction to join the northeast-oriented Elkhorn River in Rock County. East of Dry Creek is northeast-oriented Keegan Creek, which joins the southeast oriented Elkhorn River in the figure 4 east center area. Other unnamed northeast-oriented Elkhorn River tributaries are also present in Holt County. Note how Keegan Creek headwaters originate just southeast of the north-northwest oriented Dry Creek valley segment. This evidence suggests the northeast Keegan Creek valley eroded headward prior to headward erosion of the northeast-oriented Elkhorn River valley and that headward erosion of the Keegan Creek valley captured southeast oriented flood flow moving along the present day north-northwest oriented Dry Creek valley segment alignment. Headward erosion of the northeast-oriented Elkhorn River-Dry Creek valley beheaded the southeast-oriented flood flow to what was then the newly eroded Keegan Creek valley and flood waters on the northwest end of the beheaded flood flow route reversed flow direction to create the present day north-northwest oriented Dry Creek valley segment. This evidence suggests northeast-oriented Elkhorn River tributary valleys were eroded headward in sequence as the southeast-oriented Elkhorn River valley eroded headward (to the northwest). The tributaries apparently eroded to the southwest to capture southeast-oriented flood flow routes located south and west of the southeast-oriented Elkhorn River valley. Note how some of the northeast oriented Elkhorn River tributaries have southeast-oriented headwaters and/or southeast- or northwest-oriented valley segments. Again figure 4 drainage evidence is limited, and much better evidence for a massive southeast-oriented flood is found in regions northwest and southeast of the figure 4 map area.

Holt Creek-Dry Creek drainage divide area

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

Figure 5 illustrates the Holt Creek-Dry Creek drainage divide area located south and east of the figure 4 map area. Holt Creek flows in an east-northeast direction near the figure 5 north edge. Dry Creek (not the same Dry Creek as seen in figures 3 and 4) flows north from the figure 5 south center edge and then turns to flow in northeast direction to the figure 5 east center edge. Both Holt Creek and Dry Creek flow to join the southeast-oriented Elkhorn River (see figure 2). Hills in the figure 5 map area are probably sand dunes, which suggests the entire figure 5 map area is underlain by sandy soils. Note the southeast-oriented Dry Creek tributaries. These southeast-oriented tributaries routes have probably been altered by wind-blown sediment, although the southeast-orientation also probably provides evidence the northeast oriented Dry Creek valley eroded headward to capture southeast-oriented flood flow. As previously noted, based on evidence from drainage basins to the northwest and also to the southeast, an immense southeast-oriented flood flowed across this figure 5 map area. Sandy sediments in this figure 5 map region probably are flood deposited materials that have since been altered by wind action. Evidence presented in the Beaver Creek-Cedar River drainage divide area essay, the Elkhorn River-Loup River drainage divide area between Shell Creek and Beaver Creek essay, and the Elkhorn River-Shell Creek drainage divide area in Antelope, Madison, Boone, and Platte Counties essay suggests southeast-oriented flood water was merged in the southern Loup River drainage basin area with northeast and east oriented flood water in what is today the northeast and east oriented Loup River and Platte River valley area. Merging of a massive southeast-oriented flood with a large northeast and east oriented flood probably caused significant ponding of flood waters in north central and western Nebraska. Ponding of these flood waters probably resulted in the deposition of deltaic deposits that subsequently became ideal locations for sand dune formation. The southeast-oriented flood and the northeast and east oriented flood occurred at the same time, however came from different source areas or traveled by very different routes from the same source. Missouri River drainage basin landform origins research project essays published on this website  can be used to trace the southeast-oriented flood waters headward into north central Montana and southern Alberta. Essays also demonstrate the northeast and east oriented floods flowed from the Platte River headwaters area in the Wyoming and Colorado Rocky Mountains, although the source of those flood waters was also far to the northwest and west. While this interpretation requires looking at flood flow movements over a much large region than can be illustrated and discussed in this essay, the interpretation is consistent with evidence being seen in maps being illustrated here.

Cache Creek-Clearwater Creek drainage divide area

Figure 6: Cache Creek-Clearwater Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates the Cache Creek-Clearwater Creek drainage divide area south and east of the figure 5 map area. The southeast-oriented Elkhorn River is located in the figure 6 northeast corner. Clearwater Creek flows in an east-southeast direction in the figure 6 south center area and then turns northeast and east-northeast to flow to the Elkhorn River east of the figure 6 map area. Note several southeast-oriented Clearwater Creek tributaries in the figure 6 south center area and north and north-northwest oriented tributaries in the figure 6 southeast quadrant. Cache Creek flows in a northeast direction from the figure 6 west edge (south half) to join the Elkhorn River in the figure 6 northeast corner. Note an east-oriented Cache Creek segment in the figure 6 north center area and a short southeast-oriented Cache Creek segment in the figure 6 northeast quadrant. Cache Creek has no tributaries shown in the figure 6 map area. The stream in the figure 6 northwest quadrant is a different Dry Creek (from the previously seen Dry Creek) and flows east and north-northeast to join the east-southeast and east-northeast South Fork Elkhorn River located along the figure 6 north edge. Hills in the figure 6 map area again are probably sand dunes and provide evidence the figure 6 map area is underlain by sandy soils. The presence of wind-blown sand probably explains the lack of tributaries to the identifiable figure 6 map area streams. Clearwater Creek tributaries do provide evidence the Clearwater Creek valley eroded headward across multiple southeast-oriented flood flow routes. The southeast-oriented tributaries are evidence of southeast-oriented tributary valleys that were eroded headward from what was at one time the newly eroded northeast-oriented Clearwater Creek valley wall. The southeast-oriented tributary valleys were eroded by southeast-oriented flood flow moving into the newly eroded Clearwater Creek valley. Headward erosion of the northeast-oriented Cache Creek valley beheaded the southeast-oriented flood flow routes to what were then the actively eroding Clearwater Creek tributary valleys. The north and north-northwest oriented Clearwater Creek tributary valleys were eroded by reversals of flood flow on the north ends of beheaded southeast-oriented flood flow routes, which had been beheaded by headward erosion of the Clearwater Creek valley.

Elkhorn River-Loup River drainage divide area big picture view

Figure 7: Elkhorn River-Loup River drainage divide area big picture view. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 is an enlarged version of the figure 2 map to better illustrate the Elkhorn River-Loup River drainage divide area in southern Rock and Holt Counties. As already seen the Elkhorn River-Loup River drainage divide area is located in a sand dune region, where there are large areas without surface drainage routes. Reconstructions of drainage history must be made using what few surface drainage routes do exist. The  Elkhorn River originates southeast of Bassett in Rock County near the figure 7 north edge and flows southeast and northeast to the near Stuart in Holt County (also near the figure 7 north edge). From Stuart the Elkhorn River flows in a southeast direction to Atkinson, Emmet, and O’Neil before reaching the figure 7 east edge. Note Holt Creek, which is one of the longer Elkhorn River tributaries shown. Holt Creek originates near Frazier Lake in Rock County and flows in a southeast direction into western Holt County and then turns to flow in an east-northeast and northeast direction to the southeast-oriented Elkhorn River at Emmet. Note how southeast of the Holt Creek southeast-oriented valley segment and the east-southeast oriented headwaters of South Fork Elkhorn River (near Swan Lake in southwest Holt County) and further to the southeast are east-southeast oriented Cache Creek headwaters. Also note how south of Swan Lake are southeast-oriented headwaters of Big Cedar Creek and the Little Cedar Creek, which flow to the southeast-oriented Cedar River. The southeast-oriented Calamus River is located in the figure 7 southwest corner and headwaters of southeast-oriented Calamus River tributaries are found in southern Rock County. The figure 7 drainage history can be interpreted in the context of headward erosion of valleys to capture a massive southeast-oriented flood. Flood waters flowed across the entire figure 7 map area to what were at that time actively eroding southeast-oriented Loup River tributary valleys, including the Cedar River and the North Loup River-Calamus River valleys. As the Cedar River valley eroded northwest the Elkhorn River valley eroded into the figure 7 map area and the South Fork Elkhorn River valley eroded west and southwest from the newly eroded Elkhorn River valley to capture southeast-oriented flood flow routes. Headward erosion of the South Fork beheaded flow that had been moving to the newly eroded Cache Creek valley and may have beheaded flow to the southeast-oriented Big Cedar Creek valley. Headward erosion of the Elkhorn River-Holt Creek valley next beheaded flood flow routes to the newly eroded South Fork valley and beheaded any remaining southeast-oriented flood flow routes to the Cedar River headwaters. Headward erosion of the Elkhorn River valley subsequently beheaded flood flow routes to the newly eroded Holt Creek valley and perhaps some flood flow routes to actively eroding Calamus River tributary valleys. Subsequently headward erosion of the Niobrara River valley (north of the figure 7 map area) beheaded all southeast-oriented flood flow routes to the newly eroded Calamus River valley. Wind action has since created dunes and obscured all but the largest of the surface drainage routes.

Holt Creek headwaters along Rock County-Holt County border

Figure 8: Holt Creek headwaters along Rock County-Holt County border. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Holt Creek headwaters area near the Rock County-Holt County border. The north-south oriented Rock County-Holt County border is located toward the figure 8 west edge. Frazier Lake is in Rock County and is located in the figure 8 northwest corner. Holt Creek flows from west of the figure 8 west edge and is located south of Frazier Lake and flows in a southeast direction to the figure 8 southeast quadrant , where Holt Creek turns to flow in an east-northeast direction and northeast direction to join the Elkhorn River as seen in figure 7 above. Hills in the figure 8 map area appear to be stabilized sand dunes and the wind-blown sediment has definitely affected the Holt Creek route. However, the southeast-oriented Holt Creek headwaters seen here are evidence the northeast-oriented Holt Creek valley eroded headward from what at one time was the actively eroding Elkhorn River valley to capture southeast-oriented flood flow. Further north in North Dakota and in Manitoba sand dunes are commonly found on what are sometimes interpreted to be deltaic deposits associated with large glacial lakes. While the thick ice sheet that melted fast geomorphology paradigm interprets glacial history in North Dakota and Manitoba differently than the commonly accepted glacial lake interpretation, the development of sand dunes on the surface of deltaic deposits where glacial melt water floods flowed into large glacial lakes does suggest an origin for the sandy sediments responsible for the Nebraska Sand Hills development. As previously described central and western Nebraska was a location where flood waters using two completely routes came together and merged. Combining these two massive floods probably caused considerable ponding of flood waters in western and central Nebraska and flood waters flowing into this region of ponded flood water would have deposited sediments to create sandy deltaic deposits. Subsequent wind activity acting on these deltaic deposits then created the dunes seen today. As already mentioned one of the immense floods came from the northwest, flowing across central Montana, northeast Wyoming and western South Dakota, to reach north central Nebraska. The other flood flowed southeast in the present day Rocky Mountain region and was captured by headward erosion of the South and North Platte River valleys. The two floods converged in central and western Nebraska and were drained by headward erosion of what were then the deep Missouri River, Platte River, and Loup River valleys.

Holt Creek-South Fork Elkhorn River drainage divide area

Figure 9: Holt Creek-South Fork Elkhorn River drainage divide areaUnited States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Holt Creek-South Fork Elkhorn River drainage divide area south of the figure 8 map area and includes an overlap area with figure 8. Southeast and east-northeast-oriented Holt Creek is located near the north edge in the figure 9 northwest quadrant. The South Fork Elkhorn River originates north of Swan Lake in the figure 9 southeast quadrant and flows in an east, northeast, and southeast direction to the figure 9 east edge. Dry Creek originates in the Long Lake area (north of Swan Lake) and flows in a northeast direction to the figure 9 east center edge. Two southeast-oriented tributaries join Dry Creek near the figure 9 east center edge. Drainage routes in the figure 9 map area have been obscured by wind-blown sediments, however the routes that exist do provide some drainage history clues. The southeast-oriented South Fork segment, southeast-oriented Dry Creek tributaries, and the southeast-oriented Holt Creek headwaters provide evidence of southeast-oriented flood flow routes that were captured by headward erosion of the northeast-oriented South Fork Elkhorn River valley, the northeast-oriented Dry Creek valley, and the northeast-oriented Holt Creek valley in that order. Headward erosion of the South Fork Elkhorn River valley beheaded southeast-oriented flood flow to what was then the actively eroding Cedar River valley system (seen in figure 10 below). Headward erosion of the Dry Creek valley beheaded southeast-oriented flood flow to what was then the newly eroded South Fork Elkhorn River valley. Headward erosion of the Holt Creek valley next beheaded southeast-oriented flood flow to what was then the newly eroded Dry Creek valley. And, headward erosion of the Elkhorn River valley beheaded southeast-oriented flood flow to what was then the newly eroded Holt Creek valley. Valleys were probably eroded into flood-deposited deltaic sediments and wind action has subsequently created the sand dunes and obscured much of the regional drainage history evidence.

South Fork Elkhorn River-Cedar River drainage divide in Holt County

Figure 10: South Fork Elkhorn River-Cedar River drainage divide in Holt County. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10: illustrates the South Fork Elkhorn River-Cedar River drainage divide in the Holt County southwest corner and is located south of the figure 9 map area and includes overlap areas with figure 9. Note the north-south oriented Rock County-Holt County border in the figure 10 northwest quadrant and the west to east oriented Holt County-Garfield County boundary in the figure 10 south center area. South Fork Elkhorn River headwaters are located north of Swan Lake in the figure 10 northeast quadrant. The South Fork Elkhorn River as seen in figures 2 and 7 above flows generally in a northeast direction to the join the southeast-oriented Elkhorn River. Headwaters of southeast-oriented Big Cedar Creek are located in the west half of the figure 10 southeast quadrant. Big Cedar Creek as seen in figure 2 above flows to the southeast-oriented Cedar River, which flows to the northeast oriented Loup River. While figure 10 evidence is not convincing, it appears the South Fork Elkhorn River valley was eroding headward to capture southeast-oriented flood flow moving to what had been the actively eroding Cedar River valley. As seen in figures above headward erosion of the Holt Creek valley subsequently beheaded southeast-oriented flood flow to the figure 10 map area and headward erosion of he Elkhorn River valley later beheaded southeast-oriented flood flow to what was then the newly eroded Holt Creek valley. Again sand dunes and wind-blown sediments obscure much of the figure 10 drainage history evidence. The sand probably is derived from flood deposited deltaic sediments located where southeast-oriented flood waters were ponded as they converged with northeast and east oriented flood waters from west of Nebraska. Sand dunes and other eolian deposits post date the flood eroded drainage routes and have probably filled all, but the most significant of the surface drainage routes.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

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