A geomorphic history based on topographic map evidence

The Niobrara River-Snake Creek drainage divide area discussed here is located in western Nebraska, USA. Although detailed topographic maps of the Niobrara River-Snake Creek drainage divide area have been available for more than fifty years detailed map evidence has not previously been used to interpret the region’s geomorphic history. The interpretation provided here is based entirely on topographic map evidence. The Niobrara River-Snake Creek drainage divide area is interpreted to have been eroded during immense southeast-oriented flood events, the first of which flowed on a topographic surface at least as high as the highest points in the present-day drainage divide area. Flood waters probably deposited sediments from which Nebraska sand hills were developed. Flood erosion ended when headward erosion of the east-oriented Niobrara River valley captured all southeast-oriented flood flow.

Preface:

The following interpretation of detailed topographic map evidence is provided as evidence in the Missouri River drainage basin landform origins research project, which is compiling similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with and within certain adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored geomorphology paradigm, which is briefly described in the introduction below. 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 western Nebraska Niobrara River-Snake Creek drainage divide area landform origins. 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 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 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 similar essays is a thick North American ice sheet, comparable in thickness to the present day Antarctic ice sheet, occupied approximately the North American region usually recognized to have been glaciated and through its weight and erosive actions created a “deep” North American “hole”, 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 Nebraska Niobrara River-Snake Creek drainage divide area landform evidence will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Niobrara River-Snake Creek drainage divide area general location map

Figure 1: Niobrara River-Snake Creek drainage divide area general 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 general location map for the western Nebraska Niobrara River-Snake Creek drainage divide area. The state of Nebraska is enclosed by the yellow boundary line and the state of Wyoming is west of the purple boundary line. The Niobrara River flows in a southeast, east, northeast, and southeast direction across northwestern Nebraska. The labeled Niobrara tributary in the Niobrara River-Snake Creek drainage divide area is Box Butte Creek. Snake Creek is the unlabeled stream originating southeast of the Agate Fossil Beds National Monument and which flows generally in a southeast direction to east of Alliance, Nebraska. Much of the region east of the Niobrara River-Snake Creek drainage divide area is located in the Nebraska Sand Hills region and Snake Creek disappears as a surface stream when it enters the sand dune region. The Sand Hills are stabilized sand dunes that post date the region’s major drainage network development. Sand dunes obscure much of the topographic map evidence required to interpret the region’s drainage history and this essay relies on what limited evidence is available. Landform evidence illustrated in this essay is interpreted in the context of an immense southeast-oriented flood flowing across the entire figure 1 map area and which was systematically captured and diverted east and perhaps even northeast by headward erosion of deep valleys eroded into a topographic surface at least as high as the figure 1 region highest elevations today. In the figure 1 map region headward erosion of the Snake Creek valley first captured the southeast-oriented flood flow and then headward erosion of the much deeper east-oriented Niobrara River valley and its various tributary valleys captured southeast-oriented flood flow moving to what was then an actively eroding and newly eroded southeast-oriented Snake Creek valley. Detailed maps below provide evidence supporting this interpretation. Evidence of southeast-oriented flood flow in adjacent regions is described in essays under Niobrara River on the sidebar category list and also in essays listed under White River, which describes landform origins in the major east-oriented drainage basin immediately to the north of the Niobrara River drainage basin.

Niobrara River-Snake Creek drainage divide area detailed location map

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

Figure 2 provides a detailed location map for the Niobrara River-Snake Creek drainage divide area. Sioux and Box Butte Counties are located in Nebraska. The Niobrara River flows southeast and east across the northern figure 2 map area. Snake Creek headwaters originate southeast of Agate Fossil Beds National Monument and flow southeast to southwest Box Butte County where Snake Creek turns to flow towards Alliance and the Nebraska sand hills region east of Alliance. Note the numerous southeast tributaries flowing to the east-oriented Niobrara River from the north and the numerous southeast-oriented tributaries to Snake Creek and to northeast-oriented Box Butte Creek (which is a Niobrara River tributary from the south). These parallel southeast-oriented valleys were probably initiated as interconnected channels in a large southeast-oriented anastomosing channel complex formed during an immense southeast-oriented flood, which was first captured by headward erosion of the Snake Creek valley and subsequently captured by headward erosion of the deeper Niobrara River valley and the valleys of northeast-oriented Niobrara River tributaries (such as the northeast-oriented Box Butte Creek valley). Sand dune regions cover much of the area east of figure 2 and evidence for Snake Creek valley orientations east of the Alliance area cannot be determined from topographic maps. West of the sand hills region drainage history can be reconstructed from topographic map evidence. While the sand dunes obscure some desired topographic map evidence, the large sand hills region provides evidence large amounts of sandy sediment were deposited east of the figure 2 map region. Further north in North Dakota and Manitoba for example, sand dune regions are developed on sandy deltas where large glacial melt water floods entered what are usually considered to have been large standing bodies of water (or lakes). Evidence presented here is not adequate to determine whether or not the Nebraska Sand Hills region originated as such a deltaic deposit, although evidence presented here and in other essays makes a strong case for immense southeast-oriented floods moving to and across the present day Nebraska Sand Hills region.

Niobrara River-Whistle Creek drainage divide area

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

Figure 3 illustrates the Niobrara River-Whistle Creek drainage divide area southeast of Agate Fossil Beds National Monument. The Niobrara River flows southeast, northeast, and east across the figure 3 top half. Whistle Creek originates as an east-southeast oriented stream in the Royville Flat area (figure 3 south center) and then turns north and north to flow to the east-oriented Niobrara River. Note the southeast-oriented tributaries flowing to northeast and north-oriented Whistle Creek. Also note the numerous northwest-oriented tributary valleys to the northeast-oriented Niobrara River valley segment. The northwest-oriented Niobrara River tributaries and the southeast-oriented Whistle Creek tributaries are evidence the Whistle Creek valley eroded south and southwest to capture multiple southeast-oriented flood flow channels and that subsequently the deeper Niobrara River valley eroded west and southwest to capture the same southeast-oriented flood flow. Further, note the southeast-oriented Niobrara River tributary valleys on the northwest side of the northeast-oriented Niobrara River valley segment. The northwest-oriented tributary valleys were eroded by reversed flood flow on the northwest ends of the beheaded southeast-oriented flood flow routes. The southeast-oriented flood flow was probably moving in anastomosing channels (meaning the channels were interconnected) and as a result reversed flood flow moving to the deeper newly eroded Niobrara River valley head would have been able to capture flood waters from yet to be beheaded flood flow routes further to the west and southwest. Such captures of yet to be beheaded flood flow routes enabled reversed flow channels to erode deeper than might otherwise have been possible. The east-southeast oriented Royville Flat valley was probably eroded by southeast-oriented flood flow prior to headward erosion of the Niobrara River valley. The north-northeast oriented Niobrara River tributary valley extending south-southwest from Agate, Nebraska probably eroded south-southwest to capture flood flow eroding the Royville Flat valley.

Detailed map of Niobrara River-Whistle Creek drainage divide in Agate Fossil Beds National Monument area

Figure 4: Detailed map of Niobrara River-Whistle Creek drainage divide in Agate Fossil Beds National Monument area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates a detailed map of the Niobrara River-Whistle Creek drainage divide area west of Agate Fossil Beds National Monument. Northwest-oriented valleys across the figure 4 top half drain to the northeast-oriented Niobrara River. Southeast-oriented valleys in the figure 4 south half drain to the Royville Flat area and  east-southeast, northeast, and north oriented Whistle Creek. Note the southeast-oriented valley draining to the figure 4 southeast corner. Note how that southeast-oriented Whistle Creek tributary valley is linked by a through valley to a northwest-oriented Niobrara River tributary valley. Through valleys such as this one are frequently overlooked, although they provide evidence water once flowed across what are today drainage divides. In this case water was flowing southeast to what was at that time the newly eroded east-southeast, northeast, and north oriented Whistle Creek valley, which had eroded headward from what was an actively eroding Niobrara River valley headcut to capture southeast-oriented flood flow moving on yet to be beheaded flood flow routes (yet to be beheaded by Niobrara River valley headward erosion). Niobrara River valley headward erosion then captured the southeast-oriented flood flow routes and beheaded flood flow moving across the present day Niobrara River-Whistle Creek drainage divide. Flood waters on northwest ends of beheaded flood flow routes reversed flow direction to flow northwest into what was then the newly eroded and deeper northeast-oriented Niobrara River valley. There probably was not much of a time difference between headward erosion of the Whistle Creek valley and headward erosion of the northeast-oriented Niobrara River valley, so erosion on both sides of the present day Niobrara River-Whistle Creek drainage divide occurred at approximately the same time, although headward erosion of southeast-oriented Whistle Creek tributary valleys slightly preceded headward erosion of northwest-oriented Niobrara River tributary valleys.

Niobrara River-Dry Creek drainage divide area

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

Figure 4 illustrates the Niobrara River-Dry Creek drainage divide area east of the figures 3 and 4 map areas and there is no overlap. The east and northeast-oriented Niobrara River is located in the figure 5 northwest quadrant and north center. Dry Creek originates as a southeast-oriented stream and then turns northeast to flow through the figure 5 center before turning southeast, northeast, and east to flow to the figure 5 east edge and through Sand Canyon (east of the figure 5 map area) before turning northeast to flow to the Niobrara River. Southeast-oriented drainage in the figure 5 southeast quadrant flows to southeast-oriented Hemingford Creek (seen further to the southeast in figure 6 below). Note how nearly all Niobrara River tributaries from the south are northwest-oriented. This northwest orientation of Niobrara River tributaries is evidence the Niobrara River valley eroded headward across multiple southeast-oriented flood flow routes such as might be found in a southeast-oriented anastomosing channel complex. The northwest-oriented tributary valleys were eroded by reversals of flood flow on the northwest ends of the beheaded southeast-oriented flood flow routes. Southeast-oriented Dry Creek headwaters, the southeast-oriented Dry Creek valley segment, and the multiple southeast-oriented Hemingford Creek tributary headwaters provide evidence the Dry Creek valley eroded headward across the multiple southeast-oriented flood flow routes prior to headward erosion of the Niobrara River valley (although Niobrara River valley headward erosion probably closely followed Dry Creek valley headward erosion). Prior to Dry Creek valley headward erosion flood waters were flowing southeast to Hemingford Creek, which today flows southeast to the sand hills region east of Alliance, although which probably was a tributary to the east or southeast-oriented Snake Creek valley which had eroded headward to capture the flood flow.

Snake Creek tributaries west of Alliance, Nebraska

Figure 6 illustrates Snake Creek tributaries west of Alliance, Nebraska. The town located in the figure 6 southeast corner is Alliance. Snake Creek meanders along the figure 6 south edge area and is joined by multiple southeast-oriented tributaries. The predominance of southeast-oriented drainage is evidence  east-oriented Snake Creek eroded west across multiple southeast-oriented flood flow routes to capture  southeast-oriented flood flow and to divert flood waters east. Not all of the southeast-oriented streams today flow to Snake Creek. Berea Creek and Hemmingford Creek (both located north of Alliance) flow southeast to the sand hills region and appear to be headed for the east-oriented Snake Creek valley, but topographic map evidence is not adequate to say for sure. Because Snake Creek flows into the sand hills region east of Alliance and is lost as a surface stream topographic map evidence does not indicate where the Snake Creek valley eroded from, nor is it possible to say for sure that the Berea Creek and Hemingford Creek valleys eroded northwest from it. However, based on the available evidence it seems reasonable to speculate the southeast-oriented Hemingford Creek and Berea Creek valleys eroded headward from a newly eroded Snake Creek valley along southeast-oriented flood flow routes. The different orientations of the southeast-oriented Snake Creek tributaries may be reflections of the anastomosing channel patterns that existed just prior to Dry Creek valley and Niobrara River valley headward erosion to the north (which beheaded southeast-oriented flood flow to what was then the newly eroded Snake Creek valley). For example Point of Rocks Creek flows southeast from the figure 6 northwest quadrant to join east-oriented Snake Creek in the figure 6 south center. The South Branch of Point of Rocks Creek flows in a more east-southeast direction from the figure 6 west edge to join Point of Rocks Creek and south of the South Branch is southeast-oriented Barrell Springs Creek. Figure 6 evidence suggests the South Branch of Point of Rocks Creek eroded west-northwest to capture southeast-oriented flood flow moving to what had been the actively eroding southeast-oriented Barrell Springs Creek valley. Such captures would be commonplace in an ever-changing anastomosing channel complex.

Niobrara River-Sand Canyon drainage divide area

Figure 7: Niobrara River-Sand Canyon drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Niobrara River-Sand Canyon drainage divide area east of the figure 5 map area and does include overlap areas with figure 5. East of the figure 7 map area the stream flowing through Sand Canyon is named Dry Creek and was seen in figure 5. In figure 7 the stream is named Sand Canyon Creek. Note how Sand Canyon Creek is northeast-oriented, then east-oriented, southeast-oriented, and finally northeast-oriented. Note southeast-oriented tributaries to the east-oriented Niobrara River from the north and northwest-oriented tributaries from south (west of Box Butte Reservoir and near the figure 5 east edge). Also note how the northeast-oriented Sand Canyon Creek valley in the figure 7 east center has southeast-oriented tributaries from the north and northwest-oriented tributaries from the south. The southeast and northwest orientations of the Niobrara River and Sand Canyon Creek tributaries are again evidence those valleys eroded headward across multiple southeast-oriented flood flow routes such as might be found in a southeast-oriented anastomosing channel complex, The northeast-oriented Sand Canyon Creek valley (in the figure 7 east center) would have eroded southwest from what was then the actively eroding Niobrara River valley headcut to capture southeast-oriented flood flow on routes not yet beheaded by Niobrara River valley headward erosion. Headward erosion of the deep Niobrara River then beheaded the southeast-oriented flood flow to the newly eroded Sand Canyon Creek valley and directly captured the flood flow. Northeast-oriented Sand Canyon Creek tributary valleys (e.g. South Branch) eroded southwest from the actively eroding Sand Canyon Creek valley headcut in sequence (from east to west) to capture southeast-oriented flood flow that had not yet been beheaded by Sand Canyon Creek (Dry Creek) valley headward erosion. As the Sand Canyon Creek (Dry Creek) valley eroded headward (or west) it captured the southeast-oriented flood flow moving to the northeast-oriented tributary valleys and as a result headward erosion of those tributary valleys ceased.

South Branch Sand Canyon Creek-Box Butte Creek drainage divide area

Figure 8: South Branch Sand Canyon Creek-Box Butte Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the South Branch Sand Canyon Creek-Box Butte Creek drainage divide area southeast of figure 7. The northeast-oriented South Branch of Sand Canyon Creek is located in the figure 8 northwest corner. Box Butte Creek headwaters originate southeast of the northeast-oriented South Branch and flow to southeast-oriented Box Butte Creek, which in the figure 8 southeast corner turns northeast to flow to the Niobrara River (see figure 9 below). Parallel to southeast-oriented Box Butte Creek head waters, but to the southwest is southeast-oriented Hemingford Creek (which is located just south of Hemingford, Nebraska). Unlike Box Butte Creek there is no evidence Hemingford Creek turns northeast. Instead Hemingford Creek appears headed to join east-oriented Snake Creek, but both Heminford Creek and Snake Creek are lost as surface streams in the sand hills region before they meet. Southwest of Hemingford Creek is southeast-oriented Berea Creek, which also is lost as a surface stream when it reaches the sand hills region. What can be determined from the figure 8 evidence (and also figure 9 evidence) is the northeast-oriented Box Butte Creek valley eroded southwest from what was then the actively eroding Niobrara River valley headcut to capture southeast-oriented flood flow routes that had not been beheaded by Niobrara River valley headward erosion. The southeast-oriented Box Butte Creek headwaters and tributary streams provide evidence headward erosion of the Box Butte Creek valley did indeed capture multiple southeast-oriented flood flow routes. Subsequently headward erosion of the Niobrara River valley and its tributary Sand Canyon Creek and South Branch Sand Canyon Creek tributary valley beheaded flood flow to the newly eroded Box Butte Creek valley and diverted the flood water more directly to the newly eroded Niobrara River valley. Beheading of southeast-oriented flood flow across the figure 8 map area probably occurred before headward erosion of the northeast-oriented Box Butte Creek valley could erode further southwest to capture southeast-oriented flood flow eroding valleys now occupied by southeast-oriented Hemingford Creek and Berea Creek.

Niobrara River-Box Butte Creek drainage divide area

Figure 9: Niobrara River-Box Butte Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Niobrara River-Box Butte Creek drainage divide area northeast of the figure 8 map area and there is no overlap. The east-oriented Niobrara River flows across the figure 9 north edge area. Box Butte Creek flows north from the figure 9 south edge center and then turns northeast to join the Niobrara River in the figure 9 northeast corner. Figure 9 topography, especially in the southeast corner suggests this map area is on the margin of the sand hills region, which probably means surface drainage is limited to major streams. Note how northeast-oriented Box Butte Creek does have a few northwest-oriented tributaries and also has a southeast-oriented tributary. This limited evidence suggests the northeast-oriented Box Butte Creek valley eroded southwest from what was then the actively eroding Niobrara River valley headcut to capture southeast-oriented flood flow that had not yet been captured by Niobrara River valley headward erosion. The northwest-oriented Box Butte Creek tributary valleys were eroded by reversed flow on the northwest ends of beheaded flood flow routes. The reversed flood flow on those beheaded flood flow routes flowed northwest to the newly eroded northeast-oriented Box Butte Creek valley. Note how the southeast-oriented Box Butte Creek tributary has a northeast-oriented tributary that apparently eroded southwest from the southeast-oriented valley to capture yet to be beheaded southeast-oriented flood flow further to the south and southwest. Headward erosion of the deep Niobrara River valley subsequently captured all southeast-oriented flood flow moving across what is today the Niobrara River-Box Butte Creek drainage divide. Apparently flood waters deposited significant amounts of sandy sediment in the figure 9 region and sand dunes have developed more recently.

Niobrara River in the Pine Creek-Deer Creek drainage divide area

Figure 10: Niobrara River in the Pine Creek-Deer Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 illustrates the northeast-oriented Niobrara River valley in the northwest-oriented Pine Creek and Deer Creek region. Hills in the figure 10 map area appear to be sand dunes and probably are not water eroded landscape features. The sand hills have obscured all but the major drainage routes limiting evidence useful for constructing the figure 10 drainage history. The Niobrara River flows northeast across the figure 10 region to the figure 10 northeast corner. Pine Creek meanders in a northwest direction across the figure 10 center area to join the northeast-oriented Niobrara River in the figure 10 north center. Short northwest-oriented Niobrara River tributaries can be seen in the figure 10 southwest quadrant. Northwest-oriented Deer Creek joins the northeast-oriented Niobrara near the figure 10 northeast corner. Southeast-oriented Spring Creek (in the figure 10 west center) is the only figure 10 Niobrara River tributary from the north. Based on the limited evidence available the northeast-oriented Niobrara River valley eroded southwest across the figure 10 map area to capture southeast-oriented flood flow. The northwest-oriented Deer Creek and Pine Creek valleys and the short northwest-oriented Niobrara River tributary valleys originated when flood waters on the northwest ends of beheaded flood flow routes reversed flow direction to flow northwest into the newly eroded and deeper northeast-oriented Niobrara River valley. Probably the present day Deer Creek and Pine Creek valley meanders developed at least to some extent as a result of sand deposition in the original northwest-oriented valleys. The southeast-oriented Spring Creek valley eroded headward along a southeast-oriented flood flow channel from the newly eroded Niobrara River valley northwest wall.

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.