Abstract:

This essay uses topographic map evidence to interpret landform origins in the Beaver Creek-Arikaree River drainage divide area in Arapahoe, Elbert, Lincoln, and Washington Counties, Colorado. The Arikaree River originates on an escarpment surrounded upland surface and flows in an east and northeast direction to eventually join the east oriented Republican River. Beaver Creek is a north, north-northeast, and north oriented tributary to the east and northeast oriented South Platte River and Beaver Creek. Middlemist, Vega, and Sand Creeks are north-northeast and north oriented Beaver Creek tributaries, which have eroded the northwest-facing escarpment on the northwest side of the Arikaree River headwaters area. Big Sandy Creek has eroded a deep southeast oriented valley on the southeast side of the Arikaree River headwaters area and eventually flows to the east oriented Arkansas River. A deep north-to-south oriented through valley at Cedar Point (just west of the Arikaree River headwaters) links the north oriented Beaver Creek valley with the southeast oriented Big Sandy Creek valley. Shallower through valleys link the north oriented Beaver Creek tributary valleys with east and northeast oriented Arikaree River headwaters and tributary valleys. Landform features observed on topographic maps of the Beaver Creek-Arikaree River drainage divide area are interpreted to have been eroded by immense south oriented melt water floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across eastern Colorado at a time when deep east oriented valleys were eroding headward from the developing Mississippi-Missouri River drainage system to capture the massive melt water flood flow. Headward erosion of the southeast and south oriented Big Sandy Creek valley from what was at time the newly eroded east oriented Arkansas River valley first captured the south oriented flood flow. Next headward erosion of the east and northeast oriented Arikaree River valley beheaded south oriented flood flow routes to the newly eroded Big Sandy Creek valley, but was unable to capture south oriented flood flow on the Beaver Creek alignment, which had eroded a deep valley just west of Cedar Point. Headward erosion of the deep east and northeast oriented South Platte River valley next beheaded and reversed south oriented flood flow channels to the newly eroded Arikaree River and Big Sandy Creek valleys. Flood flow channels were beheaded and reversed in sequence from east to west, which meant newly beheaded and reversed flood flow channels could capture south oriented flood flow from flood flow channels further to the west. The reversal of flood flow on the Sand Creek alignment captured south oriented flood flow on the Vega Creek alignment, which was then beheaded and reversed to capture flood flow on the Middlemist Creek alignment, which was subsequently beheaded and reversed to capture south oriented flood flow on the Beaver Creek alignment, which was then beheaded and reversed to end flood flow in the Beaver Creek-Arikaree River drainage divide area.

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 the Beaver Creek-Arikaree River drainage divide area landform origins in Arapahoe, Elbert, Lincoln, and Washington Counties, Colorado. 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 Beaver Creek-Arikaree River drainage divide area landform evidence in Arapahoe, Elbert, Lincoln, and Washington Counties, Colorado will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Beaver Creek-Arikaree River drainage divide area location map

Figure 1: Beaver Creek-Arikaree 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 Beaver Creek-Arikaree River drainage divide area in Arapahoe, Elbert, Lincoln, and Washington Counties, Colorado and illustrates northeast Colorado with small areas of northwest Kansas and southwest Nebraska along the east edge. The Wyoming border is located along the north edge of figure 1 (west of Nebraska). The South Platte River flows in a north-northeast direction from the west edge of figure 1 (near southwest corner) to Denver and then to near Greeley where it turns to flow in a southeast and east direction to flow to Fort Morgan before turning in a northeast direction to flow to the north edge of figure 1 (near northeast corner of Colorado). North and east of figure the South Platte River joins the North Platte River to form the Platte River with water eventually reaching the Missouri and Mississippi Rivers. North oriented South Platte River tributaries seen in the southwest quadrant of figure 1 are flowing on the Colorado Piedmont and include Kiowa Creek, Bijou Creek, and Beaver Creek. Beaver Creek originates near the south edge of figure 1 (west of center) and flows in a north-northeast direction to join the South Platte River near Brush. The South Fork Republican River flows in a northeast direction across the southeast corner of figure 1. East of figure 1 the South Fork Republican River flows into southern Nebraska and joins the east oriented Republican River, which eventually turns in a southeast direction to flow into Kansas and to join the Kansas River with water eventually reaching the Missouri and Mississippi Rivers. The Arikaree River originates near the Beaver Creek headwaters and flows in a northeast direction to Haigler (in southwest corner of Nebraska) and then joins the east oriented Republican River. The Beaver Creek-Arikaree River drainage divide area investigated in this essay is located in the south center area of figure 1 and is east of Beaver Creek, north of the Arikaree River, and south of the highway passing through the towns of Last Chance and Lindon.

The South Platte, Arikaree, and Republican Rivers and other drainage routes seen in figure 1 developed during immense south oriented floods from the western margin of a thick North American ice sheet. Floodwaters flowed from western Canada to and across the region seen in figure 1 at a time when deep east oriented valleys were eroding headward into Colorado from a developing Mississippi-Missouri River drainage system. South oriented flood flow was captured south of figure 1 by headward erosion of the east and southeast oriented Arkansas River. Next headward erosion of east oriented Kansas River tributary valleys captured the south oriented flood flow and beheaded flood flow routes to the newly eroded Arkansas River valley. Headward erosion of the Smoky Hill River and Smoky Hill River tributary valleys into eastern Colorado (south of figure 1) captured the south oriented flood flow, with headward erosion of the South Fork Republican River valley next capturing the flood flow and headward erosion of the Arikaree River valley subsequently beheading flood flow routes to the newly eroded South Fork Republican River valley. Headward erosion of the southeast, east, and northeast oriented South Platte River valley from western Nebraska next beheaded south oriented flood flow routes to the newly eroded Arikaree River and then proceeded to behead south oriented flood flow on the Colorado Piedmont west of the newly eroded Arikaree River valley head. Floodwaters on north ends of the beheaded flood flow routes reversed flow direction to flow in north directions to the deeper southeast, east, and northeast oriented South Platte River and to create north oriented South Platte River tributary drainage routes and the north-northeast oriented South Platte River drainage route (south of Greeley). South oriented flood flow channels were beheaded and reversed in sequence from east to west, which permitted newly beheaded and reversed flood flow channels to capture yet to be beheaded flood flow from flood flow channels further to the west. These captures of yet to beheaded flood flow played an important role in the development of north oriented South Platte River tributary drainage systems such as the Beaver Creek drainage system.

Detailed location map for Beaver Creek-Arikaree River drainage divide area

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

Figure 2 provides a detailed location map for the Beaver Creek-Arikaree River drainage divide area in Arapahoe, Elbert, Lincoln, and Washington Counties, Colorado. County lines are shown and Adams, Arapahoe, Elbert, and Washington Counties are labeled. Lincoln County is east of Elbert County, south of Washington County, and west of Kit Carson County. Cedar Point is a small town (railroad siding) in eastern Elbert County. Beaver Creek originates near Cedar Point and flows in a north-northeast direction across the east margin of Arapahoe County and then across the northwest corner of Washington County to reach the north edge of figure 2 (east of center). North of figure 2 Beaver Creek flows in a north direction to join the east and northeast oriented South Platte River with water eventually reaching the Platte, Missouri, and Mississippi Rivers. Just west of Cedar Point are headwaters of a north-northwest oriented stream, which near Agate joins north-northwest oriented East Bijou Creek, which in Adams County joins West Bijou Creek to form north-northeast oriented Bijou Creek. North of figure 2 Bijou Creek flows to the east and northeast oriented South Platte River. Big Sandy Creek flows in a northeast direction from the south edge of figure 2 (west half) to the towns of Ramah, Simla, Matheson, Resolis, and River Bend (near Cedar Point) and then turns to flow in a southeast direction to Limon and Hugo before reaching the south edge of figure 2. South of figure 2 Big Sandy Creek flows in a southeast and south direction to join the east oriented Arkansas River, which eventually flows directly to the Mississippi River. The Arikaree River originates north of River Bend and flows in an east-northeast and northeast direction to near the northeast corner of Lincoln County and then flows in a northeast direction to Cope and the east edge of figure 2. East of figure 2 the Arikaree River flows in a northeast direction to join the east oriented Republican River with water eventually reaching the Kansas, Missouri, and Mississippi Rivers. An important Arikaree River tributary in this essay is its North Fork, which originates near the northwest corner of Lincoln County and which flows in an east-northeast direction to join the Arikaree River in southern Washington County. North of the North Fork is east-northeast and east-southeast oriented Gordon Creek, which flows primarily in southern Washington County and which joins the Arikaree River west of Cope. Important Beaver Creek tributaries in this essay include Middlemist Creek, Plum Bush Creek, and Sand Creek. Middlemist Creek originates just north of the Arikaree River headwaters and flows in a north direction to join Beaver Creek near the northeast corner of Arapahoe County. Plum Bush Creek originates near the southwest corner of Washington County with the West and East Forks flowing in north directions to join north of Last Chance and to form north oriented Plum Bush Creek. Sand Creek originates south of Lindon and flows in a north direction to Lindon and then in a north and north-northwest direction to join Beaver Creek near the northwest corner of Washington County. The long unlabeled northeast, north, northeast, and north oriented Sand Creek tributary located between Sand Creek and Plum Bush Creek is Vega Creek, which is another important stream in this essay. As seen in figure 2 the Beaver Creek and Arikaree River headwaters is a major triple drainage divide with water flowing in north directions to the South Platte River, in south directions to the Arkansas River , and in east and east-northeast directions to the Arikaree-Republican River.

Beaver Creek-Big Sandy Creek drainage divide area

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

Figure 3 provides a topographic map of Beaver Creek-Big Sandy Creek drainage divide area. The map contour interval for figure 3 is 10 meters. Cedar Point is a railroad siding name near the west edge of figure 3. South oriented streams originating near Cedar Point are tributaries to southeast oriented Big Sandy Creek, which eventually joins the east-oriented Arkansas River. Other south oriented streams flowing to the south edge of figure 3 are also Big Sandy Creek tributaries. Beaver Creek originates a short distance north of Cedar Point and flows in a north and north-northeast direction to the north edge of figure 3 (west half). North of figure 3 Beaver Creek flows in a north-northeast and north direction to join the east and northeast oriented South Platte River. Cedar Point is also the name of a landform in the west center area of figure 3. The Cedar Point landform is the western tip of an escarpment surrounded upland surface drained by the east and east-northeast oriented Arikaree River, which flows to the east edge of figure 3 (north half). East of figure 3 the Arikaree River flows in an east-northeast and northeast direction to eventually join the east oriented Republican River. The Cedar Point landform is a triple drainage divide with drainage to the south being to the Arkansas River, drainage to the north being to the South Platte River, and drainage to the east being to the Arikaree and Republican Rivers. The Cedar Point landform has an elevation (at the Radio Tower) greater than 1820 meters. Between the Cedar Point railroad siding and the Cedar Point landform is a north to south oriented through valley linking the north oriented Beaver Creek valley with south oriented Big Sandy Creek tributary valleys. The Cedar Point railroad siding is also located in a through valley linking south oriented Big Sandy Creek tributary valleys with north-northwest oriented Bijou Creek tributary valleys (west of figure 3), with Bijou Creek being a north oriented South Platte River tributary. South and west of these two through valleys (and of figure 3) elevations rise to more than 1820 meters. The deepest through valleys in the Cedar Point region have elevations of between 1740 and 1750 meters suggesting the through valleys are at least 70 meters deep. The through valleys were eroded by south and south-southeast oriented flood flow moving from the present day north oriented Beaver Creek and Bijou Creek alignments to the southeast and south oriented Big Sandy Creek valley and then to what at that time was the newly eroded east oriented Arkansas River valley. Prior to erosion of the deep through valleys floodwaters flowed on a surface at least as high as the upland surface drained today by the east oriented Arikaree River. The south oriented Lake Creek drainage basin (seen in southeast quadrant of figure 3) was eroded by south oriented flood flow crossing the upland surface prior to headward erosion of the shallow east oriented Arikaree River valley, which drained the upland surface at the time when headward erosion of the much deeper east and northeast oriented South Platte River valley (north of figure 3) was beheading and reversing flood flow routes to create north oriented South Platte River tributary drainage routes including the north oriented Beaver Creek and Bijou Creek drainage routes.

Detailed map of Beaver Creek-Big Sandy Creek drainage divide area

Figure 4: Detailed map of Beaver Creek-Big Sandy Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Beaver Creek-Big Sandy Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. The landform Cedar Point is located in the northwest quadrant of section 8 and reaches an elevation of 5991 feet. North oriented streams flowing to the north edge of figure 4 are headwaters of north oriented Beaver Creek, which north of figure 4 flows to the east and northeast oriented South Platte River. South oriented streams flowing to the south edge of figure 4 are tributaries to southeast and south oriented Big Sandy Creek (south of figure 4), which flows to the east oriented Arkansas River. The northeast oriented stream on the upland surface in section 4 (near northeast corner of figure 4) is the Arikaree River. East and north of figure 4 the Arikaree River flows in an east-northeast and northeast direction to join the east oriented Republican River. A north-to-south oriented through valley in the southwest corner of section 7 links a north oriented Beaver Creek headwaters valley with a south oriented Big Sandy Creek tributary valley and has an elevation of between 5680 and 5700 feet.  In the northeast corner of section 14 another through valley has an elevation of between 5700 and 5720 feet. South and west of figure 4 elevations rise to more than 5940 feet suggesting the through valleys are approximately 200 feet deep. The through valleys are probably deeper channels eroded by diverging and converging south oriented flood flow channels into the floor of a broader through valley between the high points. The south oriented flood flow was moving from the present day north oriented Beaver Creek alignment to the southeast and south oriented Big Sandy Creek valley and then to what at that time was the newly eroded east oriented Arkansas River valley. The purpose of figure 4 is to document that south oriented flood flow once crossed the region prior to headward erosion of the deeper east and northeast oriented South Platte River valley (north of figure 4). Headward erosion of the South Platte River valley beheaded the south oriented flood flow channels in sequence from east to west. Floodwaters on north ends of the beheaded flood flow reversed flow direction to create north oriented South Platte River tributary drainage routes including the north oriented Beaver Creek drainage route. Note shallow through valleys (defined by a single contour line on each side) crossing the Cedar Point upland surface. These through valleys are evidence south oriented flood flow once crossed that upland surface.

Beaver Creek-Middlemist Creek drainage divide area

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

Figure 5 illustrates a topographic map of the Beaver Creek-Middlemist Creek drainage divide area north and east of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 5 is 10 meters. The Arikaree River flows in an east and east-northeast direction across the south margin of the southeast quadrant of figure 5. East of figure 5 the Arikaree River flows in an east-northeast and northeast direction to join the east oriented Republican River. Middlemist Creek originates north of the south center edge of figure 5 and flows in a northeast, north, and northeast direction (near the Elbert-Lincoln County line) to the north edge of figure 5 (east of center). North of figure 5 Middlemist Creek flows in a north direction to join north-northeast and north oriented Beaver Creek. Beaver Creek flows in a north-northeast and north-northwest direction from the west edge of figure 5 (south half) to the north edge of figure 5 (west half) and north of figure 5 flows to the east and northeast oriented South Platte River. Prior to headward erosion of the deep east and northeast oriented South Platte River valley north of figure 5 this region was crossed by south oriented flood flow. Headward erosion of the deep South Platte River valley beheaded the south oriented flood flow routes in sequence from east to west and floodwaters on north ends of beheaded flood flow routes reversed flow to create north oriented drainage routes. Because flood flow routes were beheaded in sequence from east to west and because flood flow channels were anastomosing (diverging and converging) reversed flood flow on a newly beheaded and reversed flood flow route could capture south oriented flood on a yet to be beheaded flood flow route further to the west. To illustrate how such captures took place note the Beaver Creek-Middlemist Creek drainage divide area just east of where Beaver Creek turns to flow in a north-northwest direction.  Not only are Beaver Creek and Middlemist Creek quite close together at that point, there is a shallow through valley linking the Beaver Creek and Middlemist Creek valleys. The through valley is defined by one 10-meter contour line on the northeast side and a series of similar through valleys to the northeast link north-northwest oriented Beaver Creek tributary valleys with the north-northeast oriented Middlemist Creek valley. These through valleys were eroded by south-southeast oriented flood flow moving to the newly reversed flood flow route on the present day north-northeast oriented Middlemist Creek alignment. In other words flood flow on the Middlemist Creek alignment was beheaded and reversed while flood flow was still moving in a south direction on the Beaver Creek alignment and reversed flood flow on the Middlemist Creek alignment captured south oriented flood flow still moving on the Beaver Creek alignment.

Detailed map of Beaver Creek-Middlemist Creek drainage divide area

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

Figure 6 provides a detailed topographic map of the Beaver Creek-Middlemist Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet except near the south edge where the contour interval is 10 feet. Beaver Creek flows in a northeast direction from the south edge of figure 6 (west half) to section 27 and then turns to flow in a north-northwest direction to the west edge of figure 6 (near northwest corner). West and north of figure 6 Beaver Creek flows in a north-northeast and north direction to join the east and northeast oriented South Platte River. Middlemist Creek flows in a north and north-northeast direction from the south center edge of figure 6 to the northeast corner of figure 6. North and east of figure 6 Middlemist Creek turns to flow in a north and north-northwest direction to join north oriented Beaver Creek. North-northwest oriented streams flowing to the north edge of figure 6 are tributaries to north-northeast oriented Beaver Creek. A through valley near the east center edge of section 27 links the north-northwest oriented Beaver Creek valley with a northeast oriented Middlemist Creek tributary valley. The through valley floor elevation appears to be approximately 5250 feet. Elevations to the north rise to at least 5300 feet suggesting the through valley is approximately 50 feet deep. Shallower through valleys in sections 23, 24, and 18 link north-northwest oriented Beaver Creek tributary valleys with the north-northeast oriented Middlemist Creek valley. The through valleys were eroded by south-southeast oriented flood flow moving to reversed flood flow on what at that time was the newly beheaded and reversed Middlemist Creek alignment. Not all south oriented flood flow on the Beaver Creek alignment was captured by reversed flood flow on the Middlemist Creek alignment. Some of the south oriented flood flow moved in a south direction on the present day northeast oriented Beaver Creek alignment to the Big Sandy Creek alignment as seen in figures 3 and 4. This south oriented flood flow eroded the a deeper Beaver Creek valley prior to being beheaded and reversed to create the present day Beaver Creek drainage route. Today the Beaver Creek valley floor in section 27 is approximately 100 feet lower in elevation than the Middlemist Creek valley floor in section 25 immediately to the east.

Middlemist Creek-North Fork Arikaree River drainage divide area

Figure 7: Middlemist Creek-North Fork Arikaree River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates a topographic map of the Middlemist Creek-North Fork Arikaree River drainage divide area north and east of figure 5 and there is an overlap area with figure 5. The map contour interval for figure 7 is 10 meters. Middlemist Creek flows in a north-northeast and north direction from the west edge of figure 7 (south half) to the north edge of figure 7 (west half). North of figure 7 Middlemist Creek joins north-northeast and north oriented Beaver Creek, which flows to the east and northeast oriented South Platte River. Vega Creek originates near the south edge of figure 7 (west half) and flows in a northeast, north, and northeast direction to the north center edge of figure 7. North of figure 7 Vega Creek flows in a northeast and north direction to join north-northwest and north oriented Sand Creek, which joins north oriented Beaver Creek. The North Fork Arikaree River flows in a northeast and east direction across the southeast corner of figure 7. East of figure 7 the North Fork flows in an east direction to join the northeast oriented Arikaree River, which flows to the east oriented Republican River. Gordon Creek originates in the center of figure 7 and flows in a northeast direction to the east edge of figure 7 (north half). East of figure 7 Gordon Creek flows in a northeast, southeast, and east-southeast direction to join the northeast oriented Arikaree River. To visualize in very simplistic terms how south oriented floodwaters eroded the north oriented valleys seen in figure 7 think of south oriented flood flow channels first being captured by headward erosion of the northeast oriented North Fork Arikaree River valley, which caused floodwaters to flow in southeast direction to reach the deeper North Fork valley. Headward erosion of the Gordon Creek valley then captured south and southeast oriented flood flow in the east half of figure 7. Headward erosion of the deep east and northeast oriented South Platte River valley north of figure 7 next began to behead and reverse the south oriented flood flow channels in sequence from east to west. Flood flow on the Sand Creek alignment (north and east of figure 7-see figure 9) was beheaded and reversed first and headward erosion of a northeast oriented valley captured yet to be beheaded flood flow from the Vega Creek alignment. Headward erosion of that northeast oriented valley began to create the northwest-facing escarpment along the northwest side of the Arikaree River upland surface. When the next south oriented flood flow channel was beheaded and reversed to create the north oriented Vega Creek the process was repeated with the Middlemist Creek and Beaver Creek drainage routes to create the northwest-facing escarpment and the northeast oriented segments of the north oriented Vega, Middlemist, and Beaver Creek drainage routes with each successive valley (from east to west) being deeper than the valley immediately to the east. Many additional details can be added to this simplistic explanation to fully explain evidence seen in figure 7.

Detailed map of Middlemist Creek-North Fork Arikaree River drainage divide area

Figure 8: Detailed map of Middlemist Creek-North Fork Arikaree River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 provides a detailed topographic map of the Middlemist Creek-North Fork Arikaree River drainage divide area seen in less detail figure 7. The map contour interval for figure 8 is 20 feet except near the south edge where the contour interval is 10 feet. North-northwest oriented streams in the northwest corner of figure 8 are tributaries to north oriented Middlemist Creek, which joins north-northeast and north oriented Beaver Creek, which then flows to the east and northeast oriented South Platte River. Vega Creek flows in a northeast, east, north-northeast, and north direction from the south edge of figure 8 (near southwest corner) to the north edge of figure 8 (east of center). North of figure 8 Vega Creek flows in a north, northeast, and north direction to join north-northwest oriented Sand Creek, which flows  to north oriented Beaver Creek. The North Fork Arikaree River flows in a northeast and east direction from the south edge of figure 8 (west of center) to the east edge of figure 8 (south half). East of figure 8 the North Fork flows in an east direction to join the northeast oriented Arikaree River, which eventually joins the east oriented Republican River. Evidence for through valleys crossing drainage divides can be seen in figure 8. For example in the northeast quadrant of section 30, the northwest corner of section 29, and in section 20 through valleys can be seen crossing the Vega Creek-North Fork Arikaree River drainage divide. Most of the through valleys are defined by a single contour line and are shallow, but the through valleys provide evidence for southeast and south oriented flood flow channels that once crossed the region. A shallow through valley in section 24 links a northeast and east oriented Vega Creek tributary valley with a southeast oriented Vega Creek tributary valley. The southeast oriented Vega Creek tributaries provide additional evidence headward erosion of the Vega Creek valley captured southeast oriented flood flow. North-northwest oriented Vega Creek tributaries were created by reversals of flood flow on north and northwest ends of beheaded flood flow routes. North-northwest oriented Middlemist Creek tributary valleys in the northeast quadrant of section 23 and the southwest corner of section 14 are also linked by a through valley with the with the northeast and east oriented Vega Creek tributary valley.

Vega Creek-Gordon Creek drainage divide area

Figure 9: Vega Creek-Gordon Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates topographic map of the Vega Creek-Gordon Creek drainage divide area north and east of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 10 meters. Vega Creek flows in a north, northeast, and north direction from the south edge of figure 9 (near southwest corner) to the north edge of figure 9 (west of center). North of figure 9 Vega Creek flows in a north direction to join north-northwest oriented Sand Creek, which flows to north oriented Beaver Creek, which flows to the east and northeast oriented South Platte River. Gordon Creek flows in a northeast, southeast, and east direction from the south edge of figure 9 (west of center) to the east edge of figure 9. East of figure 9 Gordon Creek flows in a northeast, southeast, and east-southeast direction to join the northeast oriented North Fork Arikaree River, which eventually flows to the east oriented Republican River. The unlabeled north-northwest and north-northeast oriented stream originating north and slightly west of where Gordon Creek changes its direction of flow (from northeast to southeast) and flowing to the north edge of figure 9 (east half) is Sand Creek, which north of figure 9 flows in a north-northwest and north direction to join Beaver Creek. A through valley slightly east of the north center edge area of figure 9 links the north-northeast oriented Sand Creek valley with the northeast oriented Vega Creek valley segment and is approximately 30 meters deep (based on elevations just north of figure 9). Remember the progression of north-northeast and north oriented valleys seen along the northwest side of the northwest-facing escarpment bounding the Arikaree River drainage basin surface. First was Beaver Creek, then Middlemist Creek with Vega Creek next, and here in figure 9 is Sand Creek. The escarpment was probably carved as a northeast oriented flood flow channel was formed and then systematically beheaded and reversed as headward erosion of the deeper east and northeast oriented South Platte River valley north of figure 9 beheaded and reversed south oriented flood flow channels supplying floodwaters to the evolving northeast oriented flood flow channel. Because the south oriented flood flow channels were beheaded and reversed in sequence from east to west each successive flood flow channel reversal resulted in a deeper north-northeast and north oriented valley, which is a reverse of the regional slope (which is to the northeast).

Detailed map of Vega Creek-Sand Creek drainage divide area

Figure 10: Detailed map of Vega Creek-Sand Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Vega Creek-Sand Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. Vega Creek meanders in a north direction near the west edge of figure 10. North of figure 10 Vega Creek flows in a north-northwest and north direction to join north-northwest oriented Sand Creek, which flows to north oriented Beaver Creek, which then flows to the east and northeast oriented South Platte River. A northwest oriented tributary originates near the south center edge of figure 10 and joins Vega Creek near the south edge of section 12 (in northwest corner of figure 10). Sand Creek flows in a north direction from the south edge of figure 10 (east half) into section 15 and then turns to flow in a northeast direction to the north edge of figure 10 (east half). North of figure 10 Sand Creek turns to flow in a north-northwest and north direction to eventually join north oriented Beaver Creek. A through valley near the corner of sections 16, 17, 20, and 21 links a northeast oriented Sand Creek tributary valley with the northwest oriented Vega Creek tributary valley. The through valley floor elevation at the road intersection is shown as being 5003 feet. Elevations in section 9 to the north rise to 5088 feet suggesting the through valley is approximately 80 feet deep. The through valley was eroded at the time headward erosion of the deep east and northeast oriented South Platte River valley north of figure 10 was beheading and reversing south oriented flood flow channels crossing the region seen in figure 10. Flood flow channels were beheaded and reversed in sequence, which meant flood flow on the Sand Creek alignment was beheaded and reversed to flow in a north direction while flood flow was still flowing in south direction on the Vega Creek alignment. South oriented flood flow on the Vega Creek alignment was captured by the reversed flood flow on the Sand Creek alignment and flowed in a southeast and northeast direction to reach the newly reversed Sand Creek drainage route. Headward erosion of the South Platte River valley north of figure 10 next beheaded and reversed flood flow on the Vega Creek alignment and floodwaters on the northwest end of the captured southeast-northeast oriented flood flow route reversed flow direction to create the northwest oriented Vega Creek tributary drainage route.

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.