Lodgepole Creek-Crow Creek drainage divide area landform origins in the Wyoming Laramie Mountains, USA

Authors

 

Abstract:

This essay uses topographic map evidence to interpret landform origins in the Lodgepole Creek-Crow Creek drainage divide area in the Wyoming Laramie Mountains. Lodgepole Creek and Crow Creek headwaters originate near each other in the Sherman Mountains area of the Wyoming Laramie Mountains and flow in roughly east directions to converge either in the Laramie Mountains or on the Great Plains just east of the Laramie Mountains with Lodgepole Creek being located north of Crow Creek. Once east of the Laramie Mountains Lodgepole Creek flows in an east direction into western Nebraska before finally turning in a southeast direction to join the northeast oriented South Platte River. Crow Creek also continues to flow in an east direction, but near the southeast corner of Wyoming makes an abrupt turn to flow in a south and south-southwest direction to join the east and northeast oriented South Platte River. Lodgepole Creek and Crow Creek headwaters and tributary orientations, water gaps, elbows of capture, and drainage divide characteristics are interpreted in the context of immense melt water floods that once flowed to and across the Laramie Mountains. Floodwaters were derived from the western margin of a thick North American ice sheet and flowed from western Canada into and across Wyoming. At that time the Laramie Mountains were emerging and did not stand high above surrounding regions as they do today. Lodgepole Creek and Crow Creek headwaters and tributary drainage routes originated as diverging and converging flood flow channels in a large anastomosing channel complex that crossed the emerging mountain mass. Headward erosion of a deeper south oriented flood flow channel on the present day south oriented Crow Creek alignment captured east and southeast oriented flood flow channels that are today Crow Creek headwaters and tributary drainage routes and probably also captured present day east oriented Lodgepole Creek headwaters and tributary drainage routes. Headward erosion of a deeper east oriented Lodgepole Creek valley from an actively eroding and deep northeast oriented South Platte River valley head recaptured the east oriented Lodgepole Creek headwaters and tributary drainage routes and beheaded a south and southeast oriented flood flow channel that had been supplying floodwaters to the east, south, and south-southwest oriented Crow Creek flood flow channel. The Gangplank, which is a major transportation route across the Laramie Mountains, preserves a surface on which the east oriented floodwaters once flowed.

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 Lodgepole Creek-Crow Creek drainage divide area landform origins in the Wyoming Laramie Mountains. 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 Lodgepole Creek-Crow Creek drainage divide area landform evidence in the Wyoming Laramie Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Lodgepole Creek-Crow Creek drainage divide area location map

Fig1 locmap

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

Figure 1 provides a location map for the Lodgepole Creek-Crow Creek drainage divide area in the Wyoming Laramie Mountains and illustrates a region in northern Colorado with southeast Wyoming to the north and the southwest corner of the Nebraska panhandle in the northeast corner. The Laramie Mountains (labeled “Mountains” in figure 1) are the north-to-south oriented mountain range in Wyoming located immediately east of Laramie, Wyoming. The southern extension of the Laramie Mountains in Colorado is known as the Front Range (not labeled in figure 1), which achieves higher elevations than elevations in the Laramie Mountains. The South Platte River flows in a north-northeast direction from the south center edge of figure 1 to Denver and Greeley and then turns in an east and northeast direction to the east center edge of figure 1. East of figure the South Platte River joins the southeast oriented North Platte River (which flows across the northeast corner of figure 1) to form the Nebraska Platte River, which then flows to the Missouri River. Lodgepole Creek originates near the west edge of the Laramie Mountains and just east of Laramie, Wyoming and then flows in an east direction to the east edge of figure 1 (slightly north of center). East of figure 1 Lodgepole Creek turns to flow in a southeast direction to join the northeast oriented South Platte River. Crow Creek originates near the Lodgepole Creek headwaters in the Laramie Mountains and flows in an east and east-southeast direction on the north side of the Wyoming-Colorado border before turning in a south and south-southwest direction to join the South Platte River east of Greeley. Horse Creek originates in the Laramie Mountains just north of the Lodgepole Creek headwaters and flows in an east-northeast, north, and northeast direction to join the North Platte River near the north edge of figure 1 (and also near the Wyoming-Nebraska border). The Lodgepole Creek-Crow Creek drainage divide area in the Laramie Mountains investigated in this essay is located east of Laramie and west of Cheyenne and is primarily south of Lodgepole Creek and north of Crow Creek.

Drainage routes in Wyoming, Nebraska, Colorado, and adjacent states developed during immense melt water floods from the western margin of a thick North American ice sheet at a time when regional mountain ranges were emerging. Floodwaters flowed from western Canada to and across the region seen in figure 1. Mountain ranges emerged as floodwaters flowed across them and deeply eroded surrounding regions and as ice sheet related crustal warping raised mountain masses and entire regions. Flood flow routes were constantly evolving as deep valleys eroded headward into the region and as ice sheet related crustal warping uplifted mountain masses and plateau regions. Present day drainage routes reflect conditions at the time floodwaters ceased to flow into and/or along those drainage routes. The north oriented South Platte River drainage route and tributary drainage routes in the Denver region originated as south oriented flood flow channels moving floodwaters along the eastern margin of the emerging Front Range probably to what at that time was the newly eroded southeast oriented Arkansas River valley (south of figure 1). The south oriented flood flow was beheaded by headward erosion of the deeper east and northeast oriented South Platte River valley. Floodwaters on north ends of beheaded south oriented flood flow channels reversed flow direction to flow to the much deeper east and northeast oriented South Platte River valley and to create north oriented South Platte River and tributary drainage routes. Flood flow routes were beheaded and reversed in sequence from east to west enabling newly beheaded and reversed flood flow channels to capture yet to be flood flow from flood flow channels further to the west. Ice sheet related crustal warping, which was raising elevations in Colorado, probably played a significant role in the flood flow reversals. Further to the north in southeast Wyoming floodwaters moved in east directions from west of the emerging Laramie Mountains to what at that time were the much deeper South Platte River and North Platte River valleys. As the Laramie Mountains emerged floodwaters were channeled into deeper valleys and east oriented flood flow to the newly developed Crow Creek, Lodgepole Creek, and Horse Creek drainage routes was abandoned in favor of deeper valleys to the south and north. Over time flood flow channels north of the Lodgepole Creek drainage route eroded much deeper valleys across the Laramie Mountains than flood flow channels south of Lodgepole Creek and were able to capture all flood flow west of the Laramie Mountains and to divert that flood flow to the actively eroding and deep southeast oriented North Platte River valley. That diversion of flood flow caused a major flood flow reversal in the Laramie Basin (between the Medicine Bow and Laramie Mountains) that created the north oriented Laramie River drainage route on the west side of the Laramie Mountains. The north oriented Laramie River turns to flow in an east and northeast direction across the Laramie Mountains before flowing to reach the southeast oriented North Platte River. The regional drainage history is complex, but significant pieces of that history can be determined from topographic map evidence.

Detailed location map for Lodgepole Creek-Crow Creek drainage divide area

Fig2 detlocmap

Figure 2: Detailed location map Lodgepole Creek-Crow Creek 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 Lodgepole Creek-Crow Creek drainage divide area in the Wyoming Laramie Mountains. The Wyoming-Colorado state line extends in a west to east direction across figure 2 (north of south edge). The Wyoming-Nebraska state line is located near the east edge of figure 2 and is north of the Colorado border. Green colored areas are National Forest lands, which are generally located in mountain regions. The north oriented river flowing from Laramie to the northwest corner of figure 2 is the Laramie River, which north of figure 2 turns to flow in an east and northeast direction across the Laramie Mountains and then to join the southeast oriented North Platte River. Lodgepole Creek originates in the green colored area east of Laramie, Wyoming and flows in an east-northeast and east-southeast direction to the east edge of figure 2 (north half). East of figure 2 Lodgepole Creek flows in an east direction into Nebraska before turning in a southeast direction to join the northeast oriented South Platte River. Lodgepole Creek headwaters in the Laramie Mountains actually are in the form of east oriented North Lodgepole Creek, east-northeast oriented Middle Lodgepole Creek (not labeled), and east-northeast and north oriented South Lodgepole Creek. The northeast oriented South Fork just north of the North Lodgepole Creek headwaters and flowing to the north center edge of figure 2 is the South Fork Horse Creek with water eventually reaching the southeast oriented North Platte River in Nebraska. Crow Creek originates in the Wyoming green colored area just south of the South Lodgepole Creek headwaters and also consists of several different tributaries, which include North Fork Crow Creek, Middle Crow Creek, and South Crow Creek (the South Crow Creek shown between North Crow Creek and Middle Crow Creek is a tributary to North Crow Creek). These east and east-southeast tributaries converge on the east side of the Laramie Mountains and flow in an east direction to Cheyenne and the east edge of figure 2. East of figure 2 Crow Creek turns to flow in a south and south-southwest direction to join the east and northeast oriented South Platte River. Spring Creek is an east and southeast oriented North Fork Crow Creek tributary near the center of figure 2 and on the east side of the Laramie Mountains. Lone Tree Creek originates just south of the Wyoming green colored area and flows in a southeast and east direction near highway 30 before turning near Speer to flow in a south direction to the south edge of figure 2. South of figure 2 Lone Tree Creek flows to the east and northeast oriented South Platte River a short west of where Crow Creek joins the South Platte River. The east oriented drainage routes flowing from the Laramie Mountains originated as diverging and converging flood flow channels in what was once a large-scale east oriented anastomosing channel complex. At that time the Laramie Mountains did not stand high above the Laramie Basin to the west and there was no north oriented Laramie River. Headward erosion of south oriented flood flow channels from south oriented channels on the present day north oriented South Platte River and tributary alignments captured the east oriented Lone Tree Creek flood flow channel east of the Laramie Mountains and diverted the floodwaters in a south direction. Likewise headward erosion of south oriented flood flow channels east of figure 2 captured the east oriented Crow Creek flood flow channel. Probably at about that point of time east oriented flood flow to the Crow Creek, Lodgepole Creek, and Horse Creek headwaters was beheaded by headward erosion of a deeper southeast oriented valley along the route now used by the highway from Laramie to Tie Siding and Virginia Dale. However, south and southeast oriented flood flow on that route was beheaded and reversed by headward erosion of the much deeper east and northeast oriented Laramie River valley across the emerging Laramie Mountains from the much deeper southeast oriented North Platte River valley. The history of that valley is addressed in a separate Laramie River-North Fork Cache la Poudre River drainage divide area essay.

South Lodgepole Creek-North Branch North Crow Creek drainage divide area

Fig3 SLodgepoleNBrNCrow

Figure 3: South Lodgepole Creek-North Branch North Crow Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the South Lodgepole Creek-North Branch North Crow Creek drainage divide area. The map contour interval for figure 3 is 20 meters. The west flank of the Laramie Mountains is located near the west edge of figure 3 and the Laramie Basin is located west of figure 3. Elevations in the Laramie Basin west of figure 3 are in the 2200 meters range. The Sherman Mountains are located in the south center area of figure 3 and are mall range in the larger Laramie Mountains. Elevations in the northern Sherman Mountains exceed 2700, which is 500 meters higher than the Laramie Basin floor elevation to the west. South Lodgepole Creek originates near the Ski Lifts on the north side of the Sherman Mountains and flows in an east direction to the east edge of figure 3 (north of center). The Middle and North Branches of Middle Lodgepole Creek originate just north of the South Lodgepole Creek headwaters and flow in east directions to converge and form east-northeast oriented Middle Lodgepole Creek, which flows to the east edge of figure 3 (north half). North Lodgepole Creek originates north of the North Branch Middle Lodgepole Creek and flows in a northeast and east direction to the northeast corner of figure 3. The North and South Branches of North Fork Crow Creek originate east of the Sherman Mountains and converge at Upper North Crow Reservoir to form east oriented North Fork Crow Creek, which flows to the east edge of figure 3 (south of center). Middle Crow Creek originates on the west side of the Sherman Mountains and flows in a south-southeast direction to the south center edge of figure 3 and south of figure 3 turns to flow in an east direction. The highway in Telephone Canyon makes use of a shallow through valley or notch in the Laramie Mountains crest ridge linking the northwest oriented Telephone Canyon valley with the east oriented South Lodgepole Creek valley and the south-southeast oriented Middle Crow Creek valley. The through valley floor elevation is between 2620 and 2640 meters. Elevations to the north and south of the through valley rise to more than 2700 meters suggesting the through valley is at least 60 meters deep. While today a minor landform the through valley is a water-eroded feature and was eroded by east oriented flood flow moving from west of the Laramie Mountains to the Lodgepole Creek and Crow Creek valleys. Other similar through valleys or notches can be found at heads of other Lodgepole Creek and Crow Creek tributaries. These through valleys or notches were eroded at a time when elevations west of the Laramie Mountains were at least as high as elevations in the Laramie Mountains. Since that time crustal warping has raised the Laramie Mountains and floodwaters have eroded the Laramie Basin with the combined result that today there is almost a 500 meter difference in elevation between the Laramie Basin floor to the west and elevations of the through valleys or notches crossing the Laramie Mountains.

Detailed map of South Lodgepole Creek-North Fork Crow Creek drainage divide area

Fig4 detSLodgepoleMCrow

Figure 4: Detailed map of South Lodgepole Creek-North Fork Crow 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 South Lodgepole Creek-North Fork Crow Creek drainage divide area just south of figure 3 and seen in less detail in figure 5. The map contour interval for figure 4 is 40 feet. Telephone Canyon drains to the northwest corner of figure 4. Middle Crow Creek originates near the Rest Area in section 26 and flows in a south-southeast direction to the south center edge of figure 4. South of figure 4 Middle Crow Creek turns to flow in more of an east direction. South Lodgepole Creek originates in section 23 and flows in an east and east-northeast direction to the northeast corner of figure 4. A through valley or pass is located in section 23 and links the northwest oriented Telephone Canyon valley with the east oriented South Lodgepole Creek valley and has an elevation of 8590 feet. Elevations in the Sherman Mountains to the southeast of the through valley exceed 9000 feet and while not seen in figure 4 elevations north of the through valley exceed 8800 feet. These elevations suggest the through valley is at least 210 feet deep. The highway interchange in section 26 is located in a through valley or pass linking the northwest oriented Telephone Canyon valley with the south-southeast oriented Middle Crow Creek valley. The elevation of this second through valley or pass is between 8600 and 8620 feet. Elevations in section 3 (near southwest corner of figure 4) exceed 8720 feet suggesting the second through valley is at least 100 feet deep. These two through valleys or passes are used today by a major transcontinental highway and tell an interesting story. The through valleys or passes were eroded by converging and diverging east oriented flood flow channels at a time when the Laramie Mountains had yet to emerge. At that time floodwaters could flow from west of figure 4 (where elevations today are 1500 feet lower than the through valley or pass elevations) across the emerging Laramie Mountains and then in an east direction toward deep valleys eroding headward into western Nebraska. Uplift of the Laramie Mountains, which occurred as floodwaters were flowing across them, and deep erosion of the Laramie Basin on the west side of the Laramie Mountains beheaded the east oriented flood flow channels and probably first diverted the floodwaters in a south and southeast direction. Later the south and southeast oriented flood flow route was blocked by uplift and reversed when headward erosion of much deeper east and northeast oriented valleys across the Laramie Mountains beheaded flood flow routes in the Laramie Basin to create the north oriented Laramie River drainage route. Middle Crow Creek flows in an east direction from the west edge of figure 5 (near southwest corner) to Granite Springs Reservoir and then in southeast direction

South Lodgepole Creek-North Fork Crow Creek drainage divide area

Fig5 SLodgepoleNCrow

Figure 5: South Lodgepole Creek-North Fork Crow Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the South Lodgepole Creek-North Fork Crow Creek drainage divide area east and slightly north of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. Figure 5 illustrates the east side of the Laramie Mountains. Middle Lodgepole Creek flows in a northeast direction across the northwest corner of figure 5. South Lodgepole Creek flows in an east, northeast, east, and northeast direction from the west edge of figure 5 (north half) to the north edge of figure 5 (east half). North of figure 5 South Lodgepole Creek flows in a north direction to join east-northeast oriented Middle Lodgepole Creek and to form east-northeast oriented Lodgepole Creek. South Lodgepole Creek has eroded a 120-meter deep or deeper water gap across the north end of Mesa Mountain near the north center edge of figure 5. East oriented Bean Creek has eroded an equally deep water gap at Cheyenne Pass just to the north of the South Lodgepole Creek water gap. The water gaps provide evidence of diverging and converging flood flow channels on an erosion surface at least 120 meters higher than the floors of the valleys today. The North and South Branches of North Fork Crow Creek flow from the west center edge area of figure 5 to Upper North Crow Reservoir to form North Fork Crow Creek, which then flows in an east, southeast, east, and southeast direction to join east oriented Crow Creek, which flows to the east edge of figure 5 (near southeast corner). North Fork Crow Creek has eroded a 140-meter deep water gap at the south end of Table Mountain (near center of figure 5), which provides more evidence that drainage routes were established at a time when Mesa and Table Mountains did not stand high above surrounding regions. Spring Creek is a south-southeast oriented North Fork Crow Creek tributary in the east half of figure 5. Middle Crow Creek flows in an east direction from the west edge of figure 5 (near southwest corner) to Granite Springs Reservoir and then in a southeast direction to Crystal Lake Reservoir before turning to flow in an east direction to join northeast oriented South Crow Creek (near the southeast corner of figure 5) and to form east oriented Crow Creek. The railroad in the east half of figure 5 is located in major through valley linking the northeast and north oriented South Lodgepole Creek valley with the south-southeast oriented Spring Creek valley and the southeast oriented North Fork Crow Creek valley. The through valley continues in a north direction and further to the north is crossed by east-northeast oriented Horse Creek and still further to the north is drained by northeast and north oriented Chugwater Creek. The through valley was eroded along the east side of the Laramie Mountains by south oriented flood flow, which was captured near the southeast corner of figure 5 by headward erosion of the east oriented Crow Creek valley. North of figure 5 it was captured by headward erosion of the east-northeast oriented Lodgepole Creek valley and still further to the north it was captured by headward erosion of the east-northeast oriented Horse Creek valley. These and other captures occurred as deeper east oriented valleys eroded headward into the region from the deep northeast oriented South Platte River valley and the deep southeast oriented North Platte River valley, which were eroding headward into the region and capturing south oriented flood flow east of the Laramie Mountains and later in the Laramie Mountains and still later in the region west of the Laramie Mountains.

Detailed map of South Lodgepole Creek-North Fork Crow Creek drainage divide area

Fig6 detSLodgepoleNCrow

Figure 6: Detailed map of South Lodgepole Creek-North Fork Crow 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 South Lodgepole Creek-North Fork Crow Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 20 feet. Middle Lodgepole Creek flows in a northeast direction across the northwest corner of figure 6. South Lodgepole Creek flows in an east, northeast, east-southeast, east, and northeast direction from the west center edge of figure 6 to the east edge of figure 6 (near northeast corner). In the northeast quadrant of figure 6 northeast oriented South Lodgepole Creek has eroded a deep water gap across the north end of Mesa Mountain. South Lodgepole Creek crosses the 7100-foot contour line in the water gap. Elevations on either side of the water gap rise to more than 7600 feet suggesting the water gap is at least 500 feet deep. A short distance north of the South Lodgepole Creek water gap is a second water gap at Cheyenne Pass. Bean Creek is the east oriented South Lodgepole Creek tributary flowing through Cheyenne Pass. The Bean Creek valley in Cheyenne Pass has an elevation of about 7050 feet. Elevations on the ridge north of Cheyenne Pass rise to 7566 feet suggesting the Cheyenne Pass water gap is also approximately 500 feet deep. Today Bean Creek originates in the north center area of figure 6 and is linked with a north to south oriented through valley in the southwest quadrant of section 10 with the northeast oriented South Lodgepole Creek water gap. The Bean Creek-South Lodgepole Creek through valley floor elevation is 7290 feet and elevations both to the east and to the west exceed 7600 feet suggesting the through valley is more than 300 feet deep. The through valley is probably a strike valley, but it is also a water-eroded valley. Probably it was eroded by south oriented flood flow moving along the west side of Mesa Mountain and Table Mountain at the same time the Cheyenne Pass and South Lodgepole Creek water gaps were being eroded. Probably the northeast oriented South Lodgepole Creek water gap originated as a southwest oriented flood flow channel, which was subsequently beheaded and reversed to create the northeast oriented drainage route seen today. Upper North Crow Reservoir straddles the south edge of the southwest quadrant of figure 6. The North Fork Crow Creek flows in east direction from Upper North Crow Reservoir to the southwest corner of section 26 where it turns to flow in a southeast direction to the south edge of figure 6 (just west of Table Mountain). South oriented flood flow west of Mesa Mountain and Table Mountain was probably flowing to the southeast oriented North Fork Crow Creek valley near the southeast corner of figure 6, which at some point was captured by headward erosion of the deep east oriented Crow Creek valley (south and east of figure 6).

South Lodgepole Creek-Spring Creek drainage divide area

Fig7 SLodgepoleSpring

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

Figure 7 illustrates the South Lodgepole Creek-Spring Creek drainage divide area south of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 20 meters. South Lodgepole Creek flows in an east and north direction from the west edge of figure 7 (slightly north of center) to join east-northeast oriented Middle Lodgepole Creek (which flows from the west edge of figure 7-near northwest corner) and to form east-northeast oriented Lodgepole Creek, which flows to the north edge of figure 7 (slightly west of center). North and east of figure 7 Lodgepole Creek flows in an east direction into western Nebraska and eventually turns in a southeast direction to join the northeast oriented South Platte River. The North Fork Crow Creek flows in an east and southeast direction from the west edge of figure 7 (near southwest corner) to the south edge of figure 7 (west half). South of figure 7 North Fork Crow Creek flows in a southeast direction to join east oriented Crow Creek, which after flowing in an east direction turns to flow in a south and south-southwest direction to join the east and northeast oriented South Platte River. Spring Creek originates on Mesa Mountain (west of figure 7) and flows from the west center edge of figure 7 before turning in a south and south-southeast direction to the south edge of figure 7 (west of center). The small town of Federal is located in a north to south oriented through valley linking the south-southeast oriented Spring Creek valley with the north oriented South Lodgepole Creek segment. The through valley floor elevation is between 2060 and 2080 meters. Elevations east of the through valley rise to more than 2120 meters suggesting the through valley is at least 40 meters deep. The through valley was eroded headward by south oriented flood flow, which had been captured by headward erosion of the east oriented Crow Creek valley. At that time a diverging south oriented flood flow channel roughly followed the alignment of present day east and north oriented South Lodgepole Creek (as seen in figure 7) Headward erosion of the east-northeast oriented Lodgepole Creek valley then captured south oriented flood flow in the through valley near the present day Chadwick Reservoir Number 3 (near northwest corner of figure 7). Floodwaters on the north end of the beheaded flood flow channel on the present day east and north oriented South Lodgepole Creek alignment reversed flow direction to create an east and north oriented drainage route. This reversal suggests elevations west of figure 7 were being raised and contributed to the South Lodgepole Creek flood flow reversal, because south of Federal there was not a reversal of drainage. Perhaps the most intriguing features in figure 7 are the numerous east oriented drainage routes, which were beheaded by headward erosion of the south oriented flood flow channel from the Crow Creek valley. Today these east oriented drainage routes flow to Lodgepole Creek east of figure 7. These east oriented drainage routes originated as diverging and converging flood flow channels in a large anastomosing channel complex crossing the entire region. Headward erosion of the south oriented flood flow channel (now through valley) beheaded the east oriented flood flow channels, but headward erosion of a deeper flood flow channel on the Lodgepole Creek alignment from the  actively eroding and much deeper northeast oriented South Platte River valley then beheaded and reversed the newly eroded south oriented flood flow channel to create the through valley at Federal.

Detailed map of South Lodgepole Creek-Lodgepole Creek drainage divide area

Fig8 detSlodgepoleLodgepole

Figure 8: Detailed map of South Lodgepole Creek-Lodgepole Creek 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 South Lodgepole Creek-Lodgepole Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 20 feet. Contour lines are faint and hard to read, but enough can be seen to illustrate key points. South Lodgepole Creek flows in a north-northeast and north direction from the west edge of figure 8 (south half) to the north edge of figure 8 (west half). North of figure 8 South Lodgepole Creek joins east-northeast oriented Middle Lodgepole Creek to form east-northeast, east-southeast, and east oriented Lodgepole Creek, which eventually turns in a southeast direction to join the northeast oriented South Platte River. The railroad in the west half of figure 8 is located in the north to south oriented through valley linking the north oriented South Lodgepole Creek valley with the south and southeast oriented Spring Creek valley. The small town of Federal is located on the railroad just south of the south edge of figure 8 and the through valley floor elevation is between 6780 and 6800 feet. East oriented streams in the east half of figure 8 flow in east directions to eventually join Lodgepole Creek. These east oriented drainage routes originated as diverging and converging east oriented flood flow channels in an east oriented anastomosing channel complex. The east oriented flood flow channels were beheaded by headward erosion of a deeper south oriented flood flow channel on the alignment now used by the railroad in figure 8, with a diverging southwest oriented flood flow channel on the present day north-northeast oriented South Lodgepole Creek alignment. Evidence the east oriented flood flow channels were beheaded is found in west to east oriented through valleys linking headwaters of present day east oriented drainage routes with the north to south oriented through valley. An excellent example of such a through valley is located just north of the corner of sections 2, 3, 10, and 11 and has a floor elevation of between 6880 and 6900 feet. Elevations north and south of this west to east oriented through valley rise to more than 6940 feet suggesting the east oriented flood flow channel was at least 40 feet deep. Headward erosion of a deeper valley along the Lodgepole Creek drainage route (from the actively eroding and deep northeast oriented South Platte River valley) then beheaded flood flow in the north to south oriented through valley and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented South Lodgepole Creek drainage route seen in figure 8.

South Fork Crow Creek-Lone Tree Creek drainage divide area

Fig9 SCrowLoneTree

Figure 9: South Fork Crow Creek-Lone Tree Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the South Fork Crow Creek-Lone Tree Creek drainage divide area south and west of figure 5 and there is an overlap area with figure 5. The map contour interval for figure 9 is 20 meters. The Sherman Mountains are located near the northwest corner of figure 9. Middle Crow Creek flows in a south-southeast direction from the northwest corner of figure 9 and between Twin Mountain and Turtle Rock turns to flow in an east direction to Granite Springs Reservoir. From Granite Springs Reservoir Middle Crow Creek flows in a southeast direction to Crystal Lake Reservoir and then in an east direction to the east center edge of figure 9. East of figure 9 Middle Crow Creek joins South Crow Creek and North Fork Crow Creek to form east oriented Crow Creek, which eventually turns in a south and south-southwest direction to join the east and northeast oriented South Platte River. The North Fork Crow Creek flows in a southeast and east direction across the northeast corner of figure 9. South Crow Creek originates south of Turtle Rock and flows in an east-southeast and east-northeast direction to the east edge of figure 9 (south of center) and east of figure 9 flows to east oriented Crow Creek. The South Fork Crow Creek originates north of the highway interchange located between the towns of Granite and Buford and flows in an east, north, and east direction to the east edge of figure 9. East of figure 9 South Fork Crow Creek flows in a northeast direction to join east oriented Crow Creek. Lone Tree Creek originates in the southwest quadrant of figure 9 on the south side of the highway and flows in a southeast and south direction on the south side of the highway to the east edge of figure 9 (near southeast corner). East of figure 9 Lone Tree Creek flows in an east direction before turning to flow in a south direction to join the east and northeast oriented South Platte River. The highway and railroad are located on the South Fork Crow Creek-Lone Tree Creek drainage divide, which today serves as a major transportation route and is sometimes referred to as the Gangplank. What is remarkable about the Gangplank drainage divide is that Crow Creek headwaters and Lone Tree Creek headwaters in the area west of Buford are flowing almost adjacent to each other and then flow roughly parallel to each other for a considerable distance before Lone Tree Creek makes an abrupt turn to flow in a south direction while Crow Creek continues to flow in an east direction (before making its turn to flow in a south direction-see figures 1 and 2). The east and southeast oriented Crow Creek and Lone Tree Creek headwaters in the present day Laramie Mountains originated as diverging and converging east oriented flood flow channels crossing what were at that time the emerging Laramie Mountains. Headward erosion of a deep south oriented valley probably from a south oriented flood flow channel on the alignment of the present day north oriented South Platte River or of a present day north oriented South Platte River tributary captured the southeast and east oriented Lone Tree Creek flood flow channel and diverted floodwaters in a south direction and the deeper valley head or knick point then eroded headward along the Lone Tree Creek alignment. The capture took place east of figure 9 and did not include flood flow channels on the South Fork Crow Creek or the South Crow Creek alignments. Subsequently headward erosion of a south oriented flood flow channel captured the east oriented Crow Creek flood flow channel and the deep valley head or knick point eroded headward along the Crow Creek alignment. Headward erosion of these deeper valleys on either side of the drainage divide preserved the Gangplank as a remnant of the surface on which the east oriented anastomosing flood flow channels once flowed.

Detailed map of South Fork Crow Creek-Lone Tree Creek drainage divide area

Fig10 detSCrowLoneTree

Figure 10: Detailed map of South Fork Crow Creek-Lone Tree 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 South Fork Crow Creek-Lone Tree Creek drainage divide area seen is less detail in figure 9. The map contour interval for figure 10 is 20 feet. The highway and railroad extending in west to east direction across figure 10 are located on the Gangplank or the South Fork Crow Creek-Lone Tree Creek drainage divide. Lone Tree is located south of the Gangplank and flows in an east-northeast and east-southeast direction from the south edge of figure 10 (west half) to the east edge of figure 10. The South Fork Crow Creek flows in an east, southeast, north, and east direction from the west edge of figure 10 (north of center) to the north edge of figure 10 (near northeast corner). Spring Branch is a northeast oriented South Fork Crow Creek tributary in the northeast quadrant of figure 10. A through valley in section 8 (near Granite Springs) links the southeast and north South Fork Crow Creek valley with the northeast oriented Spring Branch valley. The through valley floor elevation is 7034 feet. The hill to the north rises to 7313 feet and the Gangplank to the south has an elevation of about 7300 feet (depending on where it is determined-the Gangplank slopes in an east direction). These elevations suggest the through valley is approximately 270 feet deep. The through valley provides evidence of diverging and converging flood flow channels typical of flood formed anastomosing channel complexes. An east oriented Lone Tree Creek tributary flows on the Gangplank surface in section 13 and near Granite in section 18 turns to flow in a southeast direction to join Lone Tree Creek. That Lone Tree Creek tributary provides further evidence of the anastomosing flood flow channels that once crossed the region. Lone Tree Creek south of Granite has an elevation of approximately 7150 feet and South Fork Crow Creek north of Granite has an elevation of about 7170 feet. The Bench Mark elevation at Granite reads 7321 feet suggesting the Gangplank at Granite is approximately 250 feet high. Near the east edge of figure 10 the Gangplank stands more than 300 feet above the surrounding valleys, but also begins to widen. The Gangplank provides evidence vast quantities of floodwaters once flowed across what was at that time an emerging mountain range. Uplift of the mountain mass and erosion in the Laramie Basin to the west ended all east oriented flood flow across the Laramie Mountains.

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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