North Platte River-Laramie River drainage divide area landform origins in the Colorado Medicine Bow Mountains, USA

Authors

 

Abstract:

This essay uses topographic map evidence to interpret landform origins in the North Platte River-Laramie River drainage divide area in the Colorado Medicine Bow Mountains. The Medicine Bow Mountains extend in a north-northwest direction from near the northwest corner of Rocky Mountain National Park in Colorado into southern Wyoming. The Laramie River originates near the south end of the Medicine Bow Mountains and flows in a north-northwest direction along the east side of the Medicine Bow Mountains into Wyoming before turning in a northeast direction. West of the Medicine Bow Mountains the north oriented North Platte River flows from North Park into Wyoming with its northwest oriented Canadian River tributary flowing along the Medicine Bow Mountains southwest side. Southwest oriented streams flow from the Medicine Bow Mountains to the northwest oriented Canadian River and to the north oriented North Platte River as barbed tributaries and are aligned with northeast oriented streams flowing from the Medicine Bow Mountains to the north oriented Laramie River. North-northwest to south-southeast oriented through valleys link headwaters valleys of Canadian River and North Platte River tributary valleys west of the present day Medicine Bow Mountains crest and also link headwaters valleys of Laramie River tributary valleys east of the Medicine Bow Mountains crest ridge. Through valleys on both sides of the present day drainage divide also provide evidence of former diverging and converging or anastomosing drainage channels. The barbed tributaries, through valleys, and anastomosing channels are interpreted in the context of immense melt water floods that crossed region as the Medicine Bow Mountains were emerging. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing to and across the Medicine Bow Mountain region. At first the Medicine Bow Mountains had not emerged and floodwaters could flow in south and southwest directions across what is today a major mountain range. The Medicine Bow Mountains emerged as south oriented floodwaters deeply eroded valleys on either side and as ice sheet related crustal warping raised the emerging mountain mass. As the Medicine Bow Mountains emerged floodwaters were channeled into south-southeast oriented flood flow channels on either side of the emerging mountain range. Headward erosion of deeper valleys east of the rising mountain crest ridge systematically beheaded southwest oriented flood flow channels. Floodwaters on north ends of beheaded flood flow routes reversed flow direction to create north and northeast oriented Laramie River tributary drainage routes. At the same time headward erosion of deeper southwest oriented valleys from a deeper south oriented flood flow channel west of the rising mountains beheaded and reversed south-southeast oriented flood flow channels west of the rising mountain crest ridge. Subsequently south oriented flood flow on the Laramie River alignment was beheaded and reversed and still later south oriented flood flow on the North Platte River alignment was beheaded and reversed to create the north oriented drainage systems seen today. Crustal warping that was raising the Medicine Bow Mountains and the entire region contributed to flood flow reversals on the Laramie River and North Platte River alignments.

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 North Platte River-Laramie River drainage divide area landform origins in the Colorado Medicine Bow 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 North Platte River-Laramie River drainage divide area landform evidence in the Colorado Medicine Bow Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

North Platte River-Laramie River drainage divide area location map

Figure 1: North Platte River-Laramie 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 North Platte River-Laramie River drainage divide area in the Colorado Medicine Bow Mountains and illustrates a region in north central and northwest Colorado and with a region in southeast Wyoming to the north of Colorado. Rocky Mountain National Park is located in the southeast quadrant of figure 1. The Medicine Bow Mountains extend in a north-northwest direction from the northwest corner of Rocky Mountain National Park into southern Wyoming. The Laramie River originates just east of the south end of the Medicine Bow Mountains and flows in a north-northwest direction to just north of the Wyoming-Colorado state line and then turns to flow in a northeast, north, and northeast direction to join the southeast oriented North Platte River near the northeast corner of figure 1. East of figure 1 the North Platte River flows into Nebraska with water eventually reaching the Platte, Missouri, and Mississippi Rivers and the Gulf of Mexico. The North Platte River originates west of Rocky Mountain National Park and flows in a north-northwest direction between the Medicine Bow Mountains and the Sierra Madre Range into Wyoming and then in a north direction to the north edge of figure 1 (west of center). North of figure 1 the North Platte River flows into central Wyoming and around the northwest end of the Laramie Mountains and then turns to flow in a southeast direction across the northeast corner of figure 1. The Colorado River originates near the northwest corner of Rocky Mountain National Park and flows in a south and southwest direction to the south center edge of figure 1 with water eventually reaching the Pacific Ocean. The North Platte River-Laramie River drainage divide area in the Colorado Medicine Bow Mountains investigated in this essay is located east of the North Platte River, west of the Laramie River, south of the Wyoming-Colorado state line, and north of Rocky Mountain National Park.

The North Platte and Laramie River drainage routes developed during immense melt water floods from the western margin of a thick North American ice sheet. Floodwaters were flowing from western Canada to and across the region seen in figure 1 at a time when the regional mountain ranges were just beginning to emerge. At first mountain ranges including the Medicine Bow Mountains had not emerged and floodwaters could flow across and along what are today major mountain barriers. Mountain ranges emerged as ice sheet related crustal warping raised the mountain ranges and uplifted the entire region seen in figure 1 and also as floodwaters deeply eroded adjacent valleys. The north oriented Laramie River drainage route east of the Medicine Bow Mountains and the north oriented North Platte River drainage route west of the Medicine Bow Mountains originated as south oriented flood flow channels delivering floodwaters to the south and southwest oriented Colorado River valley. Uplift of Colorado mountain ranges combined with headward erosion of the deep southeast oriented North Platte River valley across the south oriented flood flow routes caused reversals of flood flow on the present day north oriented Laramie River and North Platte River drainage routes. Flood flow on the Laramie River alignment east of the Medicine Bow Mountains was beheaded and reversed first to create the north, northeast, north, and northeast oriented Laramie River drainage route seen today at a time when floodwaters were still flowing in a south direction west of the Medicine Bow Mountains. For a time the newly formed Laramie River drainage route captured some of the flood flow from west of the Medicine Bow Mountains and the captured flood flow made a large U-turn around the south end of the Medicine Bow Mountains. Headward erosion of the deep southeast oriented North Platte River valley around the northwest end of the Laramie Mountains (north of figure 1) next beheaded the south oriented flood flow channels on the present day north oriented North Platte River alignment. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow in a north direction to the much deeper southeast oriented North Platte River valley and to create the north oriented North Platte River drainage route west of the Medicine Bow Mountains. These reversals of flood flow ended all flood flow to the newly eroded Colorado River valley (in the east half of figure 1), although uplift of the regional mountain ranges and entire region continued to create the high mountains seen today.

Detailed location map for North Platte River-Laramie River drainage divide area

Figure 2: Detailed location map North Platte River-Laramie 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 North Platte River-Laramie River drainage divide area in the Colorado Medicine Bow Mountains. The west to east oriented Wyoming-Colorado state line is located near the north edge of figure 2. Green colored areas are National and State Forest lands, which in this region are generally located in mountainous regions. The Medicine Bow Mountains extend in a south-southeast direction from the north center edge area of figure 2 to the south edge of figure 2 (east half). The area west of the Medicine Bow Mountains in Jackson County, Colorado is known as North Park (not labeled in figure 2). Walden is the largest town in North Park and is located in the southwest quadrant of figure 2. The North Platte River is formed west of Walden at the confluence of its south oriented North Fork and southeast and northeast oriented Roaring Fork and then flows in a north direction to the north edge of figure 2 (west half). The Michigan River flows in a northwest direction from the south center edge of figure 2 to Walden and then in a north and north-northwest direction to join the north oriented North Platte River near Cowdrey. The Canadian River flows in a northwest direction along the west side of the Medicine Bow Mountains to also join the North Platte River near Cowdrey. Southwest oriented streams flow from the Medicine Bow Mountains to join the northwest oriented Canadian River as barbed tributaries. Camp Creek is a labeled southwest oriented stream originating in the Medicine Bow Mountains near the state line and flows to the north oriented North Platte River as a barbed tributary. Chambers Lake is located just east of the Medicine Bow Mountains near the south edge of figure 2. The Laramie River originates near Chambers Lake and flows in a north, north-northwest, and north direction to the north edge of figure 2 (east of center). Labeled Laramie River tributaries originating in the Medicine Bow Mountains (from south to north) include McIntyre Creek, La Garde Creek, and Stuck Creek. These and other Laramie River tributaries flow in north and northeast directions from the Medicine Bow Mountains to join the north oriented Laramie River, although a southeast oriented stream flows to northeast oriented La Garde Creek as a barbed tributary. Study of the region seen in figure 2 reveals other barbed tributaries. The barbed tributaries provide evidence of drainage reversals on what are today north oriented drainage routes. The northeast oriented Laramie River tributaries are roughly aligned with the southwest oriented Canadian River tributaries suggesting the possibility the drainage routes were initiated by southwest oriented flood flow channels crossing the emerging Medicine Bow Mountains. If correctly interpreted headward erosion of a much deeper south oriented flood flow channel on the present day north oriented Laramie River drainage route combined with uplift of the Medicine Bow Mountains beheaded and reversed the southwest oriented flood flow channels to create northeast oriented Laramie River tributary drainage routes.

Canadian River-Laramie River drainage divide area

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

Figure 3 provides a topographic map of Canadian River-Laramie River drainage divide area. The map contour interval for figure 3 is 50 meters. The Medicine Bow Mountains extend in a north to south direction from the north edge to the south edge of figure 3 (east of center). Chambers Lake is located near the southeast corner of figure 3. Joe Wright Creek (not labeled in figure 3) flows in a north direction to Chambers Lake and then in a north-northeast direction to the east edge of figure 3. East of figure 3 Joe Wright Creek flows to the north and east oriented Cache la Poudre River with water eventually reaching the South Platte River and then the Nebraska Platte River. Fall Creek is an east-southeast oriented stream flowing into Chambers Lake. The Laramie River flows in a north direction from Chambers Lake to the north edge of figure 3 (near northeast corner). The West Branch Laramie River originates north of Clark Peak and flows in a northeast direction to join the north oriented Laramie River. A northwest to southeast oriented through valley between Clark Peak and Cameron Peak links the northeast oriented West Branch valley with the east-southeast oriented Fall Creek valley. Blue Lake is located in the through valley. The through valley elevation at the drainage divide is between 3350 and 3400 meters. Cameron Peak has an elevation of 3696 meters and Clark Peak has an elevation of 3947 meters. These elevations suggest the Blue Lake through valley is almost 300 meters deep. Rawah Creek is a northeast oriented Laramie River tributary further to the north. North to south oriented through valleys link the north oriented Rawah Creek tributary valleys with south and southeast oriented West Branch tributary valleys. South oriented flood flow channels eroded these through valleys at a time when the deep Laramie River valley to the east did not exist and when the Medicine Bow Mountains were still emerging. The through valleys also provide evidence floodwaters probably flowed on an erosion surface as high, if not higher, than the Medicine Bow Mountains crest.

West of the Medicine Bow Mountains the Michigan River flows in a northwest direction across the southwest corner of figure 3 and west of figure 3 joins the north oriented North Platte River. The South Fork Canadian River originates at Jewell Lake (near crest of Medicine Bow Mountains near south edge of figure 3) and flows in a southwest, northwest, and north-northwest direction to join the North Fork Canadian River and to form the north-northwest oriented Canadian River, which flows to the north edge of figure 3 (west half). North and west of figure 3 the Canadian River joins the north oriented North Platte River.  The North Fork Canadian River originates high in the Medicine Bow Mountains (west of Clark Peak and south of Kelly Lake) and flows in a south, west, and northwest direction to join the South Fork and to form the north-northwest oriented Canadian River. Kelly Lake drains in a north direction to north, west, and northwest oriented Kelly Creek, which flows to the north-northwest oriented Canadian River. A north to south oriented through valley links the north oriented Kelly Creek headwaters valley with the south oriented North Fork Canadian River headwaters valley. The through valley was eroded by a south oriented flood flow channel at a time when floodwaters were still flowing in a south direction along what is today the crest of the Medicine Bow Mountains. Further to the north several southwest oriented streams flow from the Medicine Bow Mountains to join the north-northwest oriented Canadian River as barbed tributaries. These barbed tributaries provide evidence of south oriented drainage routes prior to the reversal of flood flow west of what were at that time the emerging Medicine Bow Mountains.

Detailed map of West Branch Laramie River-Fall Creek drainage divide area

Figure 4: Detailed map of West Branch Laramie River-Fall 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 West Branch Laramie River-Fall Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 40 feet. Chambers Lake is located in the southeast quadrant of figure 4. Joe Wright Creek flows in a southwest direction from Chambers Lake toward Barnes Meadow Reservoir and then turns to flow in a northeast direction to the east edge of figure 4 (south of center). East of figure 4 Joe Wright Creek joins the north and east oriented Cache la Poudre River, which eventually joins the South Platte River. The Laramie River flows in a north direction from Chambers Lake to the north edge of figure 4. North of figure 4 the Laramie River flows in a north, northeast, north, and northeast direction to eventually reach the southeast oriented North Platte River. Clark Peak is located near the southwest corner of figure 4. Fall Creek originates east of Clark Peak and flows in an east-southeast direction to Chambers Lake. The West Branch Laramie River originates north of Clarks Peak and flows in a north-northeast direction to the north edge of figure 4 (west half) and north of figure 4 joins the north oriented Laramie River. A through valley between Clark Peak and Cameron Peak links the north-northeast oriented West Branch valley with the valley of a southeast oriented Fall Creek tributary. Blue Lake is located in the through valley and drains to Fall Creek. The Blue Lake Trail crosses the drainage divide north of Blue Lake at an elevation of between 11,000 and 11,040 feet. Cameron Peak rises to 12,127 feet and Clark Peak rises to 12,956 feet suggesting the through valley is more than 1000 feet deep. The through valley was eroded by a south oriented flood flow channel that probably at one time diverged from a south oriented flood flow channel on the present day north oriented Laramie River alignment and then converged with that south oriented flood flow channel in the Chambers Lake area. Also converging with the south oriented flood flow channel in the Chambers Lake area was a south-west oriented flood flow channel on the present day north oriented Joe Wright Creek alignment. South of the Chambers Lake area the south oriented flood flow channel continued on the present day north-northeast oriented Joe Wright Creek alignment to Cameron Pass and then across the present day Michigan River headwaters area to the south oriented Colorado River valley (see Michigan River-Colorado River drainage divide area along the continental divide in the Colorado Never Summer Mountains essay). Headward erosion of a deeper south oriented flood flow channel on the Laramie River alignment beheaded the diverging south-southwest and southeast oriented flood flow channel Floodwaters on the north-northeast end of the beheaded flood flow channel reversed flow direction to flow to the deeper and more direct flood flow channel on the Laramie River alignment. Later flood flow on the Laramie River alignment was reversed to create the north oriented Laramie River drainage route seen today. After flood flow across the region had ended and after the Medicine Bow Mountains had emerged as a high mountain range valley glaciers filled some of the valleys seen in figure 4. The glaciers filled pre-existing valleys and deepened and otherwise altered those flood-eroded valleys (although the glaciers did not erode new valleys).

McIntyre Creek-Rawah Creek drainage divide area

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

Figure 5 illustrates the McIntyre Creek-Rawah Creek drainage divide area north of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 50 meters. The Laramie River flows in a north direction from near the southeast corner of figure 5 to the north edge of figure 5 (near northeast corner). North of figure 5 the Laramie River flows in a north, northeast, north, and northeast direction to join the southeast oriented North Platte River. Rawah Creek originates at Rawah Lakes in the high Medicine Bow Mountains (near south center edge of figure 5) and flows in a north-northeast and northeast direction to join the north oriented Laramie River near Middle Mountain. McIntyre Creek originates at McIntyre Lake (north of Rawah Lakes) and flows in a north-northwest and northeast direction to join the north oriented Laramie River north of figure 5. The Canadian River flows in a north-northwest and northwest direction from the south edge of figure 5 (west half) to the west edge of figure 5 (north half) and west of figure 5 joins the north oriented North Platte River, which flows into central Wyoming before turning to flow in a southeast direction to where it is joined by the Laramie River and then into Nebraska. Canadian River tributaries from the Medicine Bow Mountains are generally oriented in southwest directions while Laramie River tributaries from the Medicine Bow Mountains are generally oriented in northeast directions, although McIntyre Creek headwaters flow in a north-northwest direction. North of the McIntyre Creek elbow of capture (where McIntyre Creek turns to flow in a northeast direction) are north-northwest headwaters of the South Fork La Garde Creek, which are better seen in figures 7 and 8. A north-northwest to south-southeast oriented through valley links the South Fork La Garde Creek headwaters valley with the north-northwest oriented McIntyre Creek headwaters valley and with the Rawah Creek headwaters area. The through valley is evidence of a south-southeast oriented flood flow channel that was beheaded by headward erosion of deeper northeast oriented Laramie River tributary valleys. The south-southeast oriented flood flow channel was probably linked with a south oriented flood flow channel on the Laramie River alignment by various diverging southwest oriented flood flow channels. As a deeper south oriented valley eroded headward along the Laramie River alignment these diverging southwest oriented flood flow channels were beheaded and reversed to create northeast oriented Laramie River tributary drainage routes. Middle Mountain illustrates how diverging and converging flood flow channels eroded valleys into the region. Nunn Creek flows in a west and north direction to join the Laramie River north of Middle Mountain and is linked by a through valley with a south oriented barbed tributary flowing to the north oriented Laramie at the south end of Middle Mountain. At one time the north to south oriented through valley was a diverging and converging flood flow channel, which was beheaded by headward erosion of a deeper valley on the present day Laramie River route.

Detailed map of McIntyre Creek-Rawah Creek drainage divide area

Figure 6: Detailed map of McIntyre Creek-Rawah 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 McIntyre Creek-Rawah Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. The Laramie River flows in a north-northwest direction across the northeast corner of figure 6. The crest of the Medicine Bow Mountains is shown with a dashed line extending across the southwest corner of figure 6. McIntyre Lake is located in section 31 (in southwest quadrant of figure 6) and McIntyre Creek flows in a north-northeast and then north-northwest direction from McIntyre Lake to the northwest corner of figure 6. North of figure 6 McIntyre Creek turns to flow in a northeast direction to reach the north oriented Laramie River. Rawah Creek flows in a north-northeast direction from south of figure 6 into section 32 and then turns to flow in a northeast direction to join the north oriented Laramie River near the northeast corner of figure 6. A through valley in the northwest corner of section 32 links the north-northwest oriented McIntyre Creek valley with the valley of a southeast oriented Rawah Creek tributary. The through valley floor elevation is between 10,520 and 10,560 feet. Elevations to the northeast of the through valley rise to 10,756 feet and elevations to the west of the through valley (near south edge of figure 6) exceed 12,000 feet suggesting the through valley is at least 200 feet deep. While not deep the through valley provides evidence of a south-southeast oriented flood flow channel supplying floodwaters to what at that time was the deeper northeast oriented Rawah Creek valley. Study of drainage divide divides in figure 6 reveals numerous similar through valleys linking north and northeast oriented Laramie River tributary headwaters valleys with the north-northwest oriented McIntyre Creek valley and with each other. For example Camp Lake is located near the south center edge of figure 6 and is drained by north oriented Camp Creek. A through valley links Camp Lake with the valley of a north-northwest oriented Rawah Creek tributary and is just one of many through valleys seen near the south edge of figure 6. These diverging and converging through valleys continue in a south direction to the east-northeast oriented North Fork Laramie River valley south of figure 6 and provide a continuation of the south-southeast oriented McIntyre Creek-Rawah Creek through valley. Headward erosion of the deep North Fork Laramie River valley (south of figure 6) captured the south-southeast oriented flood flow first. Next headward erosion of the deep northeast oriented Rawah Creek captured the south-southeast oriented flood flow. Floodwaters on north ends of beheaded flood flow reversed flow direction to create north oriented Rawah Creek tributary drainage routes. Next headward erosion of the deep northeast oriented McIntyre Creek valley (north of figure 6) captured the south-southeast oriented flood flow. Floodwaters on the north-northwest end of the beheaded flood flow channel reversed flow direction to create the north-northwest oriented McIntyre Creek headwaters drainage route. The flood flow captures and reversals were greatly aided by crustal warping that was raising the Medicine Bow Mountains as floodwaters flowed across them.

La Garde Creek-McIntyre Creek drainage divide area

Figure 7: La Garde Creek-McIntyre Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the La Garde Creek-McIntyre Creek drainage divide area north and west of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 50 meters. The Laramie River flows in a north, northwest, and north direction across the northeast corner of figure 7. North of figure 7 the Laramie River flows in a northeast, north and northeast direction to the southeast oriented North Platte River. The Canadian River flows in a northwest and west direction across the southwest corner of figure 7. West of figure 7 the Canadian River flows in a northwest direction to join the north oriented North Platte River. The Laramie River-Canadian River drainage divide follows the crest of the Medicine Bow Mountains and is shown with a dashed line extending from the north edge of figure 7 to the south center edge of figure 7. McIntyre Creek flows in a north, northeast, north direction from the south edge of figure 7 (east of center) to join the Laramie River near the landing strip (near northeast corner of figure 7). The South Fork La Garde Creek flows in a north-northwest direction in Shipman Park (north of McIntyre Creek headwaters) and joins southeast oriented North Fork La Garde Creek to form northeast oriented La Garde Creek, which joins the north oriented Laramie River near the north edge of figure 7. The north-northwest oriented South Fork La Garde Creek drainage route originated as a southeast and south-southeast oriented flood flow channel, which continued in a south-southeast direction on the present day north-northwest oriented McIntyre Creek headwaters alignment (south of figure 7 and seen in figure 5). A through valley near the south edge of figure 7 links the north-northwest oriented South Fork La Garde Creek valley with the valley of a south-southeast and northeast oriented McIntyre Creek tributary.  The through valley is defined by three contour lines on the east suggesting the through valley is at least 100 meters deep. Pine Creek is a northeast oriented McIntyre Creek tributary located north of the northeast oriented McIntyre Creek segment seen in figure 7 and is linked by a somewhat shallower through valley with the south end of the north-northwest oriented Shipman Park valley. Study of the Medicine Bow Mountains crest reveals shallow through valleys or notches at the head of present day southwest oriented Canadian River tributary valleys. The Shipman Park drainage history determinable from evidence described above begins with diverging and converging southwest oriented flood flow channels flowing across the emerging Medicine Bow Mountains probably from a south oriented flood flow channel on the Laramie River alignment to a south oriented flood flow channel west of the present day Medicine Bow Mountains. As the Medicine Bow Mountains began to emerge a south-southeast oriented flood flow channel paralleling what is today the crest of the Medicine Bow Mountains eroded headward along the present day north-northwest oriented McIntyre Creek headwaters and South Fork La Garde Creek and southeast oriented North Fork La Garde Creek alignments and ended flood flow across the rising Medicine Bow Mountains crest ridge. Next headward erosion of a much deeper south oriented flood flow channel on the Laramie River alignment beheaded the diverging southwest oriented flood flow channels to the newly formed south-southeast oriented flood flow channel adjacent to the Medicine Bow Mountains crest ridge in sequence from south to north. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow in northeast and north directions to the much deeper south oriented flood flow channel on the Laramie River alignment. Headward erosion of these deeper northeast and north oriented valleys also beheaded and reversed the south-southeast oriented flood flow channel on the North and South Fork La Garde Creek and McIntyre Creek headwaters alignments to create the north-northwest oriented McIntyre Creek and South Fork La Garde Creek drainage routes. Crustal warping that was raising the Medicine Bow Mountains as these flood flow capture and reversal events took place greatly aided in the process.

Detailed map of South Fork La Garde Creek-McIntyre Creek drainage divide area

Figure 8: Detailed map of South Fork La Garde Creek-McIntyre 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 Fork La Garde Creek-McIntyre Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. McIntyre Creek flows in a north, northeast, and north direction from the south center edge of figure 8 to the north edge of figure 8 (near northeast corner) and north of figure 8 joins the north oriented Laramie River. Shipman Park is the north-northwest oriented basin and non-forested area extending from the west center area of figure 8 to the north edge of figure 8 (near northwest corner) and is drained by north-northwest oriented South Fork La Garde Creek. North of figure 8 north-northwest oriented South Fork La Garde Creek joins southeast oriented North Fork La Garde Creek to form northeast oriented La Garde Creek, which then flows to the north oriented Laramie River. Housmer Park is located south of the south end of Shipman Park and is drained by south-southeast and northeast oriented Housmer Creek, which flows to northeast oriented McIntyre Creek. A through valley links the north-northwest oriented South Fork La Garde Creek valley (Shipman Park) with the south-southeast oriented Housmer Creek valley (Housmer Park). The through valley elevation is shown as being 9632 feet. East of the through valley elevations rise to 10,100 feet and west of the through valley elevations rise much higher. These elevations suggest the through valley is approximately 450 feet deep. A similar through valley is located to the northeast and links the northeast oriented Pine Creek valley with the south end of the Shipman Park basin. Pine Creek flows in a northeast direction to join north oriented McIntyre Creek just north of the northeast corner of figure 8. This second through valley has an elevation of 9648 feet and is also approximately 450 feet deep. These two through valleys were eroded by floodwaters moving in a south-southeast direction on the present day north-northwest oriented South Fork La Garde Creek alignment and then flowing in a northeast direction to a deeper valley on the Laramie River alignment. Because the northeast oriented Pine Creek valley and northeast and north oriented McIntyre Creek valley captured the south-southeast oriented flood flow prior to headward erosion of the northeast oriented La Garde Creek valley (north of figure 8) the deeper Laramie River valley at that time was still probably a south oriented flood flow channel, which was eroding headward along the present day north oriented Laramie River alignment. The reversal of flood flow in the Laramie River valley probably took place after all flood flow in the region seen in figure 8 had ended.

Camp Creek-Lawrence Creek drainage divide area

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

Figure 9 illustrates the Camp Creek-Lawrence Creek drainage divide area west and north of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. The west to east oriented Wyoming-Colorado state line extends across the north half of figure 9. Streams in the northeast corner of figure 9 drain to the north oriented Laramie River (located east of figure 9). The North Platte River “meanders” in a north direction from the south edge of figure 9 (near southwest corner) to the northwest corner of figure 9. Kings Canyon is a place-name on the highway in the south center area of figure 9. Pinkham Creek originates near the south edge of the southeast quadrant of figure 9 and then flows in a northwest and west direction to join the North Platte River (near the southwest corner of figure 9). Lawrence Creek is a south oriented stream flowing next to the highway to join Pinkham Creek near Kings Canyon. Camp Creek originates near the center of figure 9 and flows in a north-northwest direction to near where the highway crosses the state line and then turns in a south-southwest, west, and southwest direction to join the north oriented North Platte River as a barbed tributary. Mountain Home is a place-name on the highway north of the state line. Pelton Creek flows in a west and northwest direction from Mountain Home to the north edge of figure 9 (west half). North of figure 9 Pelton Creek joins south and northwest oriented Douglas Creek at the south end of the Douglas Creek U-turn with Douglas Creek then flowing to the north oriented North Platte River. The highway and railroad (now abandoned) between Mountain Home and Kings Canyon are located in north to south oriented through valley drained in the south by south oriented Lawrence Creek and in the middle by the south-southwest oriented Camp Creek segment. The through valley floor elevation is between 2600 and 2650 meters. Elevations west of the through valley rise to more than 2800 meters and elevations east of the through valley rise even higher. These elevations suggest the through valley is at least 150 meters deep. The through valley was eroded by south oriented flood flow, which probably flowed in a south direction to the south edge of figure 9 (east of Sentinal Mountain and then to a south oriented flood flow channel on the present day north oriented North Platte River alignment. The west and southwest oriented Camp Creek valley was probably eroded by a diverging west and southwest oriented flood flow channel, which was able to erode a slightly deeper valley and capture the south oriented flood flow. The north oriented North Platte River drainage route seen in figure 9 originated as a south oriented flood flow channel. Uplift of the region south of figure 9 probably played a significant role in the reversal of flow on the North Platte River alignment.

Detailed map of Camp Creek-Lawrence Creek drainage divide area

Figure 10: Detailed map of Camp Creek-Lawrence 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 Camp Creek-Lawrence Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 20 feet. Camp Creek flows in a south-southwest, west, and southwest direction from the north edge of figure 10 (east half) to the west edge of figure 10 (north of center) and west of figure 10 joins the north oriented North Platte River as a barbed tributary. Lawrence Creek originates in section 35 and flows in a south direction to the south edge of figure 10 (east of center). South of figure 10 Camp Creek joins west oriented Pinkham Creek, which then flows to the north oriented North Platte River. The south-southwest oriented Camp Creek valley segment and the south oriented Lawrence Creek valley are linked by a north to south oriented through valley in section 35. The through valley floor elevation is between 8620 and 8640 feet. West of the through valley Pinkham Mountain rises to more than 9260 feet in section 10 (near south edge of figure 10). East of the through valley elevations near the east edge of section 12 (near southeast corner of figure 10) rise to more than 9400 feet. These elevations suggest the through valley is more than 600 feet deep. The through valley is a water-eroded valley and was eroded by south oriented flood flow moving across the present day Medicine Bow Mountains. At that time the Medicine Bow Mountains had not emerged as a high mountain range and floodwaters could still cross what is today a high mountain range. The west and southwest oriented Camp Creek valley segment was eroded by a west and southwest oriented diverging flood flow channel. Study of that west and southwest oriented Camp Creek valley reveals parallel through valleys such as the through valley seen along the south edge of section 28. To the east of section 28 a through valley links the southeast oriented Bear Draw valley with the west oriented Camp Creek valley. A northwest to southeast oriented through extends across section 33 and links the west oriented Camp Creek valley with the south oriented Lawrence Creek valley. These and other less obvious through valleys provide evidence of what was a complex pattern of anastomosing flood flow channels crossing the Medicine Bow Mountains. At first flood flow in these valleys was in a south direction, but as the Medicine Bow Mountains emerged deeper valleys beheaded and reversed flow in shallower valleys to create an ever-changing pattern of flood flow routes. In time all floodwaters were channeled into deeper south oriented flood channels on either side of the emerging mountain mass and then those south oriented flood flow channels were beheaded and reversed to create north oriented drainage routes as ice sheet related crustal warping raised the entire region.

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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