Abstract:

This essay uses topographic map evidence to interpret landform origins in the Douglas Creek-Laramie River drainage divide area in the Wyoming Medicine Bow Mountains. The Medicine Bow Mountains extend in a north-northwest direction across the Colorado-Wyoming border with the north-northwest oriented North Platte River valley located along the west flank and the north and northeast oriented Laramie River draining the east flank. Douglas Creek originates in the high Wyoming Medicine Bow Mountains adjacent to the North Platte River-Laramie River drainage divide and flows in a southeast, south, southwest, and northwest direction to join the North Platte River. The Laramie River flows in a north-northwest direction along the Medicine Bow Mountains east flank before turning at the south end of Sheep Mountain to flow in a northeast direction into the Laramie Basin. The south to north oriented Centennial Valley is located west of Sheep Mountain and is drained by the north and northeast oriented Little Laramie River, which eventually joins the Laramie River. Most secondary drainage routes in the high Medicine Bow Mountains are oriented in south directions and join north oriented drainage routes as barbed tributaries. Through valleys cross most drainage divides, including the Little Laramie River-Laramie River drainage divide at the south end of Sheep Mountain, and provide evidence of earlier south oriented drainage routes. The barbed tributaries, elbows of capture, valley orientations, and through valleys are interpreted in the context of immense melt water floods, which crossed the region at a time when the Medicine Bow Mountains were just beginning to emerge. Floodwaters were derived from the western margin of a thick North American ice sheet and flowed from western Canada to and across the Medicine Bow Mountains region. Emergence of the Medicine Bow Mountains occurred as floodwaters deeply eroded adjacent valleys and basins and as continental ice sheet related crustal warping raised the mountain range and the entire region. At first floodwaters flowed in a south and southeast directions along what is today the Medicine Bow Mountain crest. As the Medicine Bow Mountains emerged headward erosion of deeper valleys from south oriented flood flow channels on either side of the emerging mountain mass competed with each other to capture floodwaters in the Medicine Bow Mountains region. In time floodwaters were channeled to south oriented flood flow channels on the present-day North Platte River and Laramie River (and Little Laramie River alignments. Ice sheet related crustal warping that raised the entire region combined with headward erosion of deep valleys north of the study region caused reversals of the flood flow direction on the Laramie River, Little Laramie River, and North Platte River alignments and created the present-day north oriented Laramie River, Little Laramie River, and North Platte River drainage routes.

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

Douglas Creek-Laramie River drainage divide area location map

Figure 1: Douglas Creek-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 Douglas Creek-Laramie River drainage divide area in the Wyoming Medicine Bow Mountains and illustrates a region in southern Wyoming with a region in northern Colorado to the south. The Medicine Bow Mountains extend in a north-northwest direction from the northwest corner of Colorado’s Rocky Mountain National Park into southern Wyoming. The North Platte River originates at the confluence of tributaries near Coalmont (west of the south end of the Medicine Bow Mountains) and flows in a north and north-northwest direction along the west side of the Medicine Bow Mountains to the north edge of figure 1 (west half). North of figure 1 the North Platte River flows into central Wyoming where it flows in a northeast and east direction around the northwest end of the Laramie Mountains and then in a southeast direction into Nebraska. Douglas Creek is an unlabeled south and northwest North Platte River tributary located just north of the Wyoming-Colorado state line and originates south of Medicine Bow Peak. The Laramie River originates east of the south end of the Medicine Bow Mountains (just east of Clarks Peak) and flows in a north and northeast direction to Laramie, Wyoming and then in a north-northwest and northeast direction to the north edge of figure 1 (east half). North of figure 1 the Laramie River flows to the southeast oriented North Platte River. The unlabeled southeast and northeast oriented drainage route originating south of Medicine Bow Peak and joining the Laramie River between the towns of Laramie and Bosler is the Little Laramie River. The Douglas Creek-Laramie River drainage divide area investigated in this essay is primarily located north of the Wyoming-Colorado state line, east of Douglas Creek, south of Medicine Bow Peak, and west of the Laramie and Little Laramie Rivers. The region between Douglas Creek and the North Platte River is illustrated and described in the French Creek-Douglas Creek drainage divide area landform origins in the Wyoming Medicine Bow Mountains essay.

The Medicine Bow Mountains are today a high mountain range standing more than 1000 meters above  surrounding basins and valleys. However, drainage routes in the Medicine Bow Mountains began to develop at a time when the Medicine Bow Mountains did not stand high above surrounding regions and immense melt water floods from the western margin of a thick North American ice sheet in western Canada could freely flow across what is today a high mountain barrier. The Medicine Bow Mountains emerged as floodwaters deeply eroded the surrounding valleys and basins and as ice sheet related crustal warping raised the mountain range and the entire region. At first floodwaters flowed in a south and south-southeast direction along what is now the crest of the Medicine Bow Mountains. The north oriented Laramie River and north-northwest oriented North Platte River alignments originated as south oriented flood flow channels on either side of the emerging mountain mass. Early in the Medicine Bow Mountains emergence process a south-southeast and south oriented flood flow channel flowed on the present day south oriented Douglas Creek headwaters alignment to join what was at that time  a southeast oriented flood flow channel on the present day northwest oriented Douglas Creek segment alignment and then to continue in a southeast and east direction to a south oriented flood flow channel on the present day north oriented Laramie River alignment. The southeast oriented flood flow channel on the present day northwest oriented Douglas Creek segment alignment diverged from a south-southeast oriented flood flow channel on the present day north-northwest oriented North Platte River alignment. The southeast oriented Little Laramie River headwaters likewise are flowing on the alignment of a southeast and south oriented flood flow channel supplying floodwaters to a south oriented flood flow channel on the present day north oriented Laramie River alignment. As the Medicine Bow Mountains emerged floodwaters were channeled to either side of the emerging mountain mass and the earlier formed south oriented flood flow routes were preserved as crustal warping raised the mountain range and region and ended flood flow across the Medicine Bow Mountain mass. In time uplift of the region combined with headward erosion of deep southeast oriented North Platte River valley north of figure 1 created a situation where south oriented flood flow channels on the Laramie River alignment were beheaded and reversed to create the present day north oriented Laramie River drainage system. Continued headward erosion of the deep southeast oriented North Platte River valley around the northwest end of the emerging Laramie Mountains next beheaded and reversed flood flow channels on the North Platte River alignment to create the present day North Platte River drainage system. The flood flow reversals did not affect the previously uplifted Medicine Bow Mountains region and the earlier south oriented valleys now drain to the north oriented Laramie and Little Laramie Rivers and North Platte River as barbed tributaries.

Detailed location map for Douglas Creek-Laramie River drainage divide area

Figure 2: Detailed location map Douglas Creek-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 Douglas Creek-Laramie River drainage divide area in the Wyoming Medicine Bow Mountains. The west to east oriented Wyoming-Colorado state line is located near the south edge of figure 2. Green colored areas are National Forest lands and in this region are generally located in mountain regions. The green colored area in the west half of figure 2 is in the Medicine Bow Mountains. The North Platte River flows in a north-northwest direction across the southwest corner of figure 2. Medicine Bow Peak and the Snowy Range are located near the northwest corner of figure 2. Streams labeled as French Creek, Mullen Creek, and Savage Creek flow in southwest directions from the Medicine Bow Mountains to the west edge of figure 2 and join the north-northwest oriented North Platte River west of figure 2 as barbed tributaries. Douglas Creek originates south of the Snowy Range and east of the Mullen Creek headwaters and flows in a southeast and south-southwest direction to Keystone. From Keystone Douglas Creek flows in a south and southwest direction to be joined by west and northwest oriented Pelton Creek and then to flow in a northwest direction to join the North Platte River near the west edge of figure 2. Note how the northwest oriented Douglas Creek segment turns to flow in a south direction to join the north-northwest oriented North Platte River as a barbed tributary. Mountain Home is near the state line in the west half of figure 2. Pelton Creek originates near Mountain Home and flows in a west and northwest direction to join Douglas Creek at the point where Douglas Creek turns to flow in a northwest direction. The Laramie River flows in a north direction from the south center edge of figure 2 (near highway) to Woods Landing and Jelm and then turns to flow in a northeast direction to Laramie. From Laramie the Laramie River flows in a north direction to the north edge of figure 2 (east half). The Middle Fork Little Laramie River (not labeled in figure 2) originates south of the Snowy Range and flows in a northeast, south, southeast, and east direction to join the north-northeast oriented South Fork Little Laramie River (also not labeled in figure 2) east of Deerwood and to form the north, northeast, east, and northeast oriented Little Laramie River, which flows to the north edge of figure 2 (east half). North of figure 2 the Little Laramie River joins the Laramie River. The North Fork Little Laramie River originates east of the Snowy Range and flows in a south-southeast direction near Centennial before making a U-turn to join the north and northeast oriented Little Laramie River. Note the large number of secondary drainage routes seen in figure 2 flowing in south directions to the primary north oriented drainage routes.

Pelton Creek-Boswell Creek drainage divide area

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

Figure 3 provides a topographic map of Pelton Creek-Boswell Creek drainage divide area. The map contour interval for figure 3 is 50 meters. The west to east oriented Wyoming-Colorado state line is located near the south edge of figure 3. The Laramie River flows in a north direction from the southeast corner of figure 3 to the northeast corner of figure 3. Labeled Laramie River tributaries from south to north include Johnson Creek, Boswell Creek and its Gramm Creek and Heldrich Creek tributaries, Eagle Creek, Shellrock Creek, Bear Creek, Jelm Creek, Porter Creek, Woods Creek, Fox Creek, and Squirrel Creek. Several of these tributaries, especially in the southeast quadrant of figure 3, have south and/or southeast oriented segments and/or tributaries. For example Heldrich Creek is a south oriented stream and Gramm Creek and its North Fork tributary are oriented in southeast directions, and Shellrock Creek has southeast oriented headwaters. Boswell Creek originates south of figure 3 and flows in a north direction to near Mountain Home where it turns to flow in an east direction to join the Laramie River. Mountain Home is located on the highway just north of the state line. Pelton Creek originates north of Mountain Home and flows in a south direction to near Mountain Home and then turns to flow in a west and northwest direction to the west center edge of figure 3. West of figure 3 Pelton Creek joins Douglas Creek at the point where Douglas Creek turns from flowing in a southwest direction to flowing in a northwest direction. Douglas Creek can be seen in figure 3 flowing in a southwest direction from the north edge of figure 3 (west half) to the west edge of figure 3 (north of center). West of figure 3 Douglas Creek turns to flow in a northwest direction to join the north-northwest oriented North Platte River. Pelton Creek has several south oriented tributaries including Badger Creek and the North Fork Pelton Creek. Illinois Creek has south oriented headwaters. Mountain Home is located in what is today a broad west to east oriented saddle or through valley crossing the Medicine Bow Mountains. Elevations on the Pelton Creek-Boswell Creek drainage divide near Mountain Home are between 2650 and 2700 meters. South of figure 3 elevations along the crest of the Medicine Bow Mountains rise to more than 3250 meters and further south Medicine Bow Mountains peaks rise even higher. North of figure 3 elevations at the base of the Snowy Range rise to 3250 meters with Snowy Range Peaks rising even higher. These elevations suggest the Pelton Creek-Boswell Creek through valley (or saddle) crossing the Medicine Bow Mountains is as much as 550 meters deep. The through valley (or saddle) was eroded by southeast and east oriented flood flow moving from a south oriented flood flow channel on the present day north oriented North Platte River alignment to a flood flow channel on the present day north oriented Laramie River alignment.  At first the flood flow channel on the Laramie River alignment was oriented in a south direction, but the flow direction may have been reversed while floodwaters were still flowing in a southeast and east direction across the emerging Medicine Bow Mountains on the Pelton Creek-Boswell Creek alignments.

Detailed map of Pelton Creek-Boswell Creek drainage divide area

Figure 4: Detailed map of Pelton Creek-Boswell 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 Pelton Creek-Boswell Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. The west to east oriented Wyoming-Colorado state line extends across the south half of figure 4. Mountain Home is a small community located along the highway in the black shaded area in sections 16 and 17. Pelton Creek flows from the east edge of section 8 in an east and south direction across the southwest quadrant of section 9 and then turns to flow in a southwest and west direction across section 17 and next turns in a generally west direction to the west edge of figure 4. West of figure 4 Pelton Creek turns to flow in a northwest direction to join Douglas Creek, which then flows in a northwest direction to join the north-northwest oriented North Platte River. Heldrich Creek flows in a south and south-southeast direction from the north edge of figure 4 (east half-near highway) across the east half of section 9 and continues in a south direction to join Boswell Creek near the southeast corner of section 16. Boswell Creek flows in a north-northeast, northwest, and northeast direction from the south edge of figure 4 (east of center) to the southeast corner of section 16 and then flows in an east direction to the east edge of figure 4 (south of center-just north of state line). East of figure 4 Boswell Creek flows to the north oriented Laramie River. A west to east oriented through valley in the black shaded area in section 16 links the west oriented Pelton Creek valley with the east oriented Boswell Creek valley. The through valley floor elevation is between 8740 and 8760 feet. Elevations near the north edge of figure 4 rise to more than 9100 feet and exceed 12,000 feet on Medicine Bow Peak in the Snowy Range to the north of figure 4. Elevations near the south edge of figure 4 (west of center) exceed 9100 feet and rise to more than 10,800 feet south of figure 4 (and even higher on peaks located further to the south). Based on elevations seen in figure 4 the Pelton Creek-Boswell Creek through valley is at least 340 feet deep. Using more distant elevation an argument could be made that the Pelton Creek-Boswell Creek through valley is as much as 2000 feet deep. This significant through valley (or saddle) is at least to some extent a water-eroded feature and was eroded by southeast and east oriented flood flow moving from a south oriented flood flow channel west of the emerging Medicine Bow Mountains to a south oriented flood flow channel east of the emerging Medicine Bow Mountains. South oriented Pelton Creek and Boswell Creek tributaries seen in figure 4 were eroded by south oriented flood flow moving along what is today the crest of the Medicine Bow Mountains.

Lake Creek-Laramie River drainage divide area

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

Figure 5 illustrates the Lake Creek-Laramie River drainage divide area north and east 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 the south edge of figure 5 (east half) to Woods Landing and then turns to flow in a northeast direction to the east edge of figure 5 (north half). Bear Creek is an east oriented Laramie River tributary near the south edge of figure 5. Porter Creek and Woods Creek flow in northeast and east directions to join the north oriented Laramie River. Fox Creek flows in a northeast, east, and southeast direction to join the north oriented Laramie River as a barbed tributary. Lake Owen Creek originates near Lake Owen and flows in an east and southeast direction to join Fox Creek at the point where Fox Creek turns to flow in a southeast direction. Fox Creek tributaries include south oriented Fence Creek and Dale Creek, east and southeast oriented Strain Creek (which flows to Lake Owen Creek), northeast and east oriented Squirrel Creek, and southeast oriented Squaw Creek. Albany is a town located near the north edge of figure 5 (west of center). The South Fork Little Laramie River flows in an east direction through Albany and then turns in a northeast direction and north of figure 5 joins the north and northeast oriented Little Laramie River. A deep through valley links the east and southeast oriented Strain Creek valley with the north oriented Little Laramie River valley north of figure 5 and is better seen in figure 7. Lake Mountain is located west of Lake Owen. Lake Creek originates north of Lake Mountain and flows in a southwest and west direction to the west center edge of figure 5. West of figure 5 Lake Creek joins southwest and northwest oriented Douglas Creek to flow to the north-northwest oriented North Platte River. Muddy Creek originates near the northwest corner of figure 5 and flows in a southeast and south-southwest direction to the west edge of figure 5 (just north of Lake Creek) and west of figure 5 joins southwest and northwest oriented Douglas Creek. Note how northwest to southeast oriented through valleys south of Lake Mountain link the southwest oriented Lake Creek valley with the southeast and east oriented North Fork Squirrel Creek valley. The through valleys are shallow compared to the much deeper Little Laramie River-Strain Creek through valley to the east, but are identifiable even with a 50-meter contour interval. The through valleys were eroded by southeast oriented flood flow, which at first was moving to a south oriented flood flow channel on the present day north oriented Laramie River alignment. Headward erosion of the northeast oriented Woods Creek, Fox Creek, and Squirrel Creek valleys and of the southeast and east oriented North Fork Squirrel Creek valley captured the southeast oriented flood flow and diverted it in a northeast direction to the east and southeast oriented Fox Creek valley. Next headward erosion of the southwest oriented Lake Creek valley from the southwest oriented Douglas Creek valley (which at that time drained in a southeast direction on the present day northwest oriented Pelton Creek alignment) captured the southeast oriented flood flow and diverted the floodwaters to the Douglas Creek valley. Headward erosion of the Muddy Creek valley and its tributary valleys next captured the southeast oriented flood flow, which was coming from north of the present day Douglas Creek headwaters in what is today the high Snowy Range.

Detailed map of Lake Creek-North Fork Squirrel Creek drainage divide area

Figure 6: Detailed map of Lake Creek-North Fork Squirrel 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 Lake Creek-North Fork Squirrel Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet in the north and 20 feet in the south. Lake Creek flows in a south-southwest direction from the north edge of figure 6 (west half) to the west edge of figure 6 (south of center) and west of figure 6 flows to southwest and northwest oriented Douglas Creek, which flows to the north-northwest oriented North Platte River. Lincoln Gulch drains in a northwest direction across the southwest corner of figure 6 to join Lake Creek near the west edge of figure 6. The North Fork Squirrel Creek flows from the southwest quadrant of section 3 in a southeast, south, and east direction to the east edge of figure 6 and east of figure 6 joins east and north oriented Squirrel Creek, which then flows to northeast, east, and southeast oriented Fox Creek, which flows to the north and northeast oriented Laramie River as a barbed tributary. Northwest to southeast oriented through valleys in section 4 and the southwest corner of section 34 link northwest oriented Lake Creek tributaries with southeast oriented North Fork Squirrel Creek headwaters and tributary valleys. The section 4 through valley links the North Fork Squirrel Creek headwaters valley with the valley of a northwest oriented Lake Creek tributary and has an elevation of between 8940 and 8960 feet. Elevations to the south rise to 9087 feet and the ridge immediately to the north rises to 9368 feet. These elevations suggest the through valley is at least 100 feet deep. The through valley in the southwest corner of section 34 has a floor elevation of between 9160 and 9200 feet. Lake Mountain to the north rises to 9763 feet suggesting the through valley is at least 168 feet deep. The northwest oriented Lincoln Gulch valley is linked by somewhat shallower northwest to southeast through valleys south of figure 6 with a northeast oriented North Fork Squirrel Creek tributary valley and with the northeast oriented Squirrel Creek headwaters valley. Diverging and converging southeast oriented flood flow channels eroded these northwest to southeast oriented through valleys prior to headward erosion of the south-southwest oriented Lake Creek valley. As described in the figure 5 discussion the floodwaters were flowing from north of the present day Snowy Range to a south oriented flood flow channel on the present day north oriented Laramie River alignment. Headward erosion of the northeast oriented Fox Creek valley and its northeast and east oriented tributary valleys, including the Squirrel Creek and North Fork Squirrel Creek valleys, captured the southeast oriented flood flow and diverted the floodwaters in a northeast, east, and southeast direction to the south oriented flood flow channel on the Laramie River alignment. Next headward erosion of the deeper south-southwest oriented Lake Creek valley captured the southeast oriented flood flow and diverted the floodwaters to the southwest oriented Douglas Creek alignment and then in a southeast direction on the present day northwest oriented Pelton Creek alignment and then further east on the east oriented Boswell Creek alignment to a south oriented flood flow channel on the present day north oriented Laramie River alignment.

Little Laramie River-Laramie River drainage divide area

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

Figure 7 illustrates the Little Laramie River-Laramie River drainage divide area north and slightly west of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 7 is 50 meters (20 meters near east edge). Douglas Creek flows in a southeast and southwest direction from the northwest corner of figure 7 to Rob Roy Reservoir and then in a south direction to the south edge of figure 7 (west half-near southwest corner). South of figure 7 Douglas Creek flows in a southwest and northwest direction to join the north-northwest oriented North Platte River. Labeled Douglas Creek tributaries seen in figure 7 (from north to south) include south and southwest oriented Little Beaver Creek, southeast and south-southwest oriented Muddy Creek and its south oriented Spring Creek tributary, and southwest and west-southwest oriented Lake Creek. The Laramie River flows in a north and northeast direction from Woods Landing across the southeast corner of figure 7.  Fox Creek flows in a northwest, east, and southeast direction to join the Laramie River as a barbed tributary just north of Woods Landing. Lake Owen Creek flows in an east and southeast direction to join the southeast oriented Fox Creek segment and Strain Creek flows in an east and southeast direction to join the southeast oriented Lake Owen Creek segment. Albany is a small town located near the center of figure 7. The South Fork Little Laramie River flows in an east direction to Albany and then turns in a northeast and north-northeast direction to flow to join the Middle Fork Little Laramie River in the Centennial Valley. The Middle Fork Little Laramie River flows in a southeast and east direction from the north edge of figure 7 (west half) to join the north oriented South Fork and to form the north oriented Little Laramie River, which then flows to the north edge of figure 7 (east of center). North of figure 7 the Little Laramie River flows in a north and northeast direction to join the Laramie River. The Centennial Valley is a north to south oriented valley or basin between the Medicine Bow Mountains to the west and Sheep Mountain to the east and is today drained by the north oriented Little Laramie River. A through valley at the Centennial Valley south end links the north oriented Little Laramie River drainage basin with southeast oriented tributaries to the north and northeast oriented Laramie River. The through valley floor elevation is between 2500 and 2550 meters. Elevations on Sheep Mountain rise to more than 2950 meters. Elevations on Lake Mountain and Muddy Mountain to the west rise to more than 2950 meters. These elevations suggest the through valley linking the north oriented Laramie River valley with the north oriented Little Laramie River valley is approximately 400 meters deep. The through valley was eroded (at least to some extent) by a south oriented flood flow channel located west of the emerging Sheep Mountain mass that converged with a south oriented flood flow channel located east of the emerging Sheep Mountain mass to form a south oriented flood flow channel on the present day north oriented Laramie River alignment (south of figure 7). Crustal warping that was raising the region south of figure 7 and the Medicine Bow Mountains plus headward erosion of much deeper valleys north of figure 7 eventually resulted in reversals of flood flow on the Laramie River and Little Laramie River alignments.

Detailed map of Little Laramie River-Lake Creek drainage divide area

Figure 8: Detailed map of Little Laramie River-Lake 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 Little Laramie River-Lake Creek drainage divide area seen in figure 7 in less detail. The map contour interval for figure 8 is 40 feet. Albany is a small community located primarily in section 14 near the north edge of figure 8. The South Fork Little Laramie River flows in an east direction from the west edge of figure 8 (near northwest corner) to Albany and then turns to flow in a northeast direction to the north edge of figure 8 ((slightly west of center). North of figure 8 the South Fork flows in a north-northeast direction to join the Middle Fork and to form the north and northeast oriented Little Laramie River, which flows to the north and northeast oriented Laramie River. Lake Creek originates in section 27 and flows in a southwest and south-southwest direction to the southwest corner of figure 8. South and west of figure 8 Lake Creeks flows to southwest and northwest oriented Douglas Creek, which flows to the north-northwest oriented North Platte River. Lake Owen is primarily located in section 25. Lake Owen Creek flows in an east and south-southeast direction from Lake Owen to the east edge of figure 8. East of figure 8 Lake Owen Creek flows to the southeast oriented Fox Creek segment, which then flows to the north and northeast oriented Laramie River. Strain Creek originates in the northeast quadrant of section 26 and flows in an east-northeast, east, and southeast direction to join the south-southeast segment of Lake Owen Creek in section 29. North of the Strain Creek headwaters in section 23 an east and north oriented stream originates, which flows to the north edge of figure 8 (east half) and which north of figure 8 flows in a north-northwest direction to the South Fork Little Laramie River. A through valley in section 20 links the north oriented South Fork Little Laramie River tributary valley with a south oriented Strain Creek tributary valley. The through valley floor elevation is between 8200 and 8240 feet. Sheep Mountain to the north and east of figure 8 rises to more than 9600 feet. Lake Mountain and Muddy Mountain to the west of the through valley and seen in figure 8 rise to more than 9700 feet. These elevations suggest the South Fork Little Laramie River-Strain Creek through valley could be as much as 1360 feet deep. A somewhat different through valley between Muddy Mountain and Lake Mountain (in sections 22 and 27) links a north-northeast oriented South Fork Little Laramie River tributary valley with the southwest and south-southwest oriented Lake Creek headwaters valley. The through valley floor elevation is between 9160 and 9200 feet suggesting the through valley is more than 500 feet deep. This through valley was eroded by southwest oriented flood flow moving from the present day north oriented Little Laramie River alignment to the southwest oriented Lake Creek and Douglas Creek alignment (and then probably to a southeast oriented flood flow channel on the present day northwest oriented Pelton Creek alignment). Headward erosion of a much deeper valley on the southeast oriented Strain Creek-Lake Owen Creek, and Fox Creek route from a south oriented flood flow channel on the present day north oriented Laramie River alignment beheaded the southwest oriented flood flow route to the southwest oriented Lake Creek valley. Subsequently a reversal of flood flow in the Centennial Valley beheaded the southeast oriented flood flow route to the south oriented Laramie River valley and created the north oriented Little Laramie River drainage route, although flood flow may have entered the Centennial Valley from the west and may have further eroded the Centennial Valley floor.

Nash Fork-Middle Fork Little Laramie River drainage divide area

Figure 9: Nash Fork-Middle Fork Little Laramie River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Nash Fork-Middle Fork Little Laramie River drainage divide area north and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. Medicine Bow Peak and Browns Peak near the northwest corner of figure 9 are located in the Snowy Range. The south and south-southwest oriented stream originating south of Medicine Bow Peak and flowing to the west edge of figure 9 (south of center) is South French Creek, which west of figure 9 flows to southwest oriented French Creek, which then joins the north-northwest oriented North Platte River as a barbed tributary. Douglas Creek originates near the west edge of figure 9 (south of South French Creek) and flows in a southeast direction to the south edge of figure 9 (west half). South of figure 9 Douglas Creek flows in a southwest, south, southwest, and northwest direction to join the north-northwest oriented North Platte River. The Middle Fork Little Laramie River originates in Willow Park (north of the Douglas Creek headwaters) and flows in an east, northeast, south-southwest, southeast, and east direction into the Centennial Valley where it joins the north oriented South Fork to form the north and northeast oriented Little Laramie River. The northwest end of Sheep Mountain is located east and south of the Little Laramie River in the southeast corner of figure 9. The North Fork Little Laramie River flows in a south-southeast direction from the north center edge of figure 9 into the Centennial Valley where it makes a U-turn to join the north oriented Little Laramie River. Nash Fork originates in the Browns Peak area and flows in a southeast direction to join the south-southeast oriented North Fork Little Laramie River north of the town of Centennial.  Libby Creek is a southeast, east, and southeast oriented stream originating in the Snowy Range area and joining the south-southeast oriented North Fork Little Laramie River south of Corner Mountain (north of Centennial). The predominance of south oriented streams in the high Medicine Bow Mountains is evidence drainage routes in the Medicine Bow Mountains were developed by south oriented flood flow at a time when the Medicine Bow Mountains did not stand high above surrounding regions. Floodwaters flowed in south directions across what are today the highest regions in the Medicine Bow Mountains and the floodwaters were captured by headward erosion of deep southeast oriented valleys from the east and southwest oriented valleys from the west as the Medicine Bow Mountains emerged. Headward erosion of the South French Creek valley captured flood flow routes to the Douglas Creek and to the Middle Fork Little Laramie River valley. Interestingly shallow through valleys link the Nash Fork and Libby Creek in the region where the Ski Lifts are located (northwest of Centennial). These shallow through valleys suggest the Nash Fork and Libby Creek valleys originated as diverging and converging flood flow channels, probably at a time when the Medicine Bow Mountains were just beginning to emerge as a high mountain range.

Detailed map of Nash Fork-Libby Creek drainage divide area

Figure 10: Detailed map of Nash Fork-Libby 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 Nash Fork-Libby Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. The North Fork Little Laramie River flows in a south direction from the north edge of figure 10 (east half) to just west of Corner Mountain and then turns in a southeast and south-southeast direction to flow to the southeast corner of figure 10. South and east of figure 10 the North Fork makes a U-turn to join the north and northeast oriented Little Laramie River. Nash Fork flows from near the northwest corner of figure 10 in an east-southeast direction to Hanging Lake in section 20 and then flows in a south-southeast direction to join the North Fork Little Laramie River in the south half of section 21. Libby Creek flows in an east-northeast direction from the west edge of figure 10 (north of center) to the east center edge of section 24 and then turns to flow in southeast direction to join the southeast oriented North Fork Little Laramie River near the south edge of section 27 (south of Corner Mountain). Through valleys link the Nash Fork and Libby Creek valleys. For example near the north center edge of section 24 a northwest to southeast oriented through valley links a southeast oriented Nash Fork valley segment with a southeast oriented Libby Creek tributary valley. The through valley was probably eroded by southeast oriented flood flow diverging from a flood flow channel on the present day Nash Fork alignment and moving floodwaters to the southeast oriented Libby Creek alignment. Near the center of section 19 a much deeper through valley links the Libby Creek valley with the valley of an east-northeast oriented Nash Fork tributary. The floor elevation of this second through valley at its deepest point is slightly less than 9400 feet. Elevations at the top of the Snowy Range Ski Lift are shown as being 9646 feet suggesting this second through valley is almost 250 feet deep. This second through valley was probably eroded by an east-northeast oriented flood flow channel diverging from a flood flow channel on the Libby Creek alignment and then converging with a flood flow channel on the Nash Fork alignment. At the time these diverging and converging flood flow channels were eroded the Medicine Bow Mountains topography looked very different from it does today. The Medicine Bow Mountains at that time were still emerging and the deep Centennial Valley to the east probably did not exist (or if it did the Medicine Bow Mountains did not stand high above it as is the case today). Floodwaters at that time were still able to cross the Snowy Range area, which today is the highest region in the Wyoming Medicine Mountains, and the deep North Platte River and Laramie River valleys west and east of the emerging Medicine Bow Mountains had yet to be eroded.

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.