Encampment River-Elk River drainage divide area landform origins along the continental divide in the Wyoming and Colorado Sierra Madre Mountains and Park Range, USA

Authors

 

Abstract:

This essay uses topographic map evidence to interpret landform origins in the Encampment River-Elk River drainage divide area in the Wyoming and Colorado Sierra Madre Mountains and Park Range. The North Platte River flows in a north and north-northwest direction east of the Park Range in Colorado and northeast of the Sierra Madre Mountains, which straddle Wyoming-Colorado border, with water eventually reaching the Gulf of Mexico. The Encampment River is a north oriented North Platte River tributary and originates near the south end of the Sierra Madre Mountains The Elk River originates in the northern Park Range, just south of the Encampment River headwaters, and flows in a southwest and south direction to join the north and west oriented Yampa River with water eventually reaching the Colorado River and Pacific Ocean. Through valleys cross the east-west continental divide and link valleys of north oriented Encampment River tributaries with valleys of south oriented Elk River tributaries. Diverging and converging flood flow channels, such as those found in a large-scale anastomosing channel complex, are interpreted to have eroded the through valleys. Numerous barbed tributaries, elbows of capture, and through valleys east and west of the Encampment River-Elk River drainage divide area and through valleys linking the south oriented Elk River valley with south oriented Colorado River tributary valleys (south of the north and west oriented Yampa River valley) provide further evidence supporting the anastomosing channel complex interpretation. Floodwaters were derived from the western margin of a thick North American ice sheet and flowed from western Canada to the Colorado River valley and tributary valleys at a time when regional mountain ranges were still emerging. The Sierra Madre Mountains and Park Range and other regional mountain ranges emerged as floodwaters deeply eroded surrounding valleys and basins and as ice sheet related crustal warping raised the mountain ranges and the entire North Platte River headwaters area. Headward erosion of deep valleys across south oriented flood flow channels systematically beheaded flood flow routes and floodwaters on north ends of beheaded flood flow channels reversed flow direction to flow in a north direction to the much deeper beheading valley and to create north oriented drainage routes. The flood flow reversals were greatly aided by ice sheet related crustal warping that was raising the regional mountain ranges and the entire North Platte River headwaters area. In this manner the present day north oriented Encampment River and North Platte River drainage routes and their associated drainage systems were developed. After all flood flow across the region had ended and after the Sierra Madre Mountains and Park Range had emerged as high mountain ranges valley glaciers filled some of the flood eroded valleys and further modified the landscape.

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 Encampment River-Elk River drainage divide area landform origins in the Wyoming and Colorado Sierra Madre Mountains and Park Range. 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 Encampment River-Elk River drainage divide area landform evidence in the Wyoming and Colorado Sierra Madre Mountains and Park Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Encampment River-Elk River drainage divide area location map

Figure 1: Encampment River-Elk 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 Encampment River-Elk River drainage divide area in the Wyoming and Colorado Sierra Madre Mountains and Park Range and illustrates a region in north central Colorado and with Wyoming to the north of Colorado. Rocky Mountain National Park is located near the southeast corner of figure 1. The Medicine Bow Mountains extend in a north direction from Rocky Mountain National Park to the north edge of figure 1. West of the Medicine Bow Mountains is the north and north-northwest oriented North Platte River drainage route. North of figure 1 the North Platte River flows in a north, east, and southeast direction around the north end of the Laramie Mountains (in northeast corner of figure 1) with water eventually reaching the Gulf of Mexico. The Encampment River (unlabeled in figure 1) is a north oriented North Platte River tributary originating at the south end of Sierra Madre Mountains just south of the Wyoming-Colorado state line and flowing to the Wyoming towns of Encampment and Riverside before joining the North Platte River. The Colorado River originates in Rocky Mountain National Park and flows in a west and southwest direction to the south edge of figure 1 (east of center) and eventually reaches the Pacific Ocean. The Yampa River is formed at confluence of tributaries near Yampa, Colorad0 (north of south center edge of figure 1) and flows in a north direction to Steamboat Springs. At Steamboat Springs the Yampa River turns in a west direction to flow to the west edge of figure 1 (south half). West of figure 1 the Yampa River joins the south oriented Green River, which then flows to the southwest oriented Colorado River. The Elk River originates near the north end of the Park Range (just south of the Sierra Madre Mountains) and flows in a southwest and south direction to join the Yampa River near Steamboat Springs. The Encampment River-Elk River drainage divide area along the continental divide in the Wyoming and Colorado Sierra Madre Mountains and Park Range is located in the region where the Sierra Madre Mountains and Park Range meet just south of the Wyoming-Colorado state line.

Drainage routes seen in figure 1 developed during immense melt water floods at a time when Wyoming and Colorado mountain ranges were beginning to emerge. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across Wyoming to actively eroding Colorado River tributary and headwaters valleys. Colorado and Wyoming mountain ranges emerged as floodwaters deeply eroded surrounding valleys and basins and as ice sheet related crustal warping raised the mountain ranges and the entire region seen in figure 1. The present day northwest oriented North Platte River drainage route originated as a south-southeast and south oriented flood flow channel supplying floodwaters to the west and southwest oriented Colorado River headwaters valley. Subsequently the floodwaters were captured by reversals of south oriented flood flow in the present day north oriented Laramie River and Cache la Poudre River headwaters valleys (north of Rocky Mountain National Park). Still later a reversal of the south-southeast oriented flood flow created the north-northwest oriented North Platte River drainage route. These flood flow reversals were usually triggered by headward erosion of much deeper east oriented valleys across the south oriented flood flow channels, although the ice sheet related crustal warping that was raising the region and the regional mountain ranges contributed significantly to the flood flow reversals.

The present day north oriented Encampment River drainage route originated as a south oriented flood flow channel diverging from the south-southeast oriented flood flow channel on the present day north-northwest oriented North Platte River alignment. South oriented flood flow on the Encampment River alignment flowed to the southwest and south oriented Elk River valley, which then drained to the Yampa River valley. At first the present day north oriented Yampa River headwaters valley south of Steamboat Springs was a south oriented flood flow channel supplying floodwaters to actively eroding south oriented Colorado River tributary valleys (e.g. stream flowing from Toponas to McCoy near the south center edge of figure 1). Headward erosion of the much deeper west oriented Yampa River valley from the south oriented Green River valley (west of figure 1) captured the south oriented flood flow and diverted the floodwaters in a west and south direction to the Colorado River valley. Floodwaters on the north end of the beheaded flood flow route reversed flow direction to flow in a north direction to the much deeper west oriented Yampa River valley and to create the north oriented Yampa River headwaters drainage route. South oriented flood flow on the Encampment River alignment was subsequently beheaded and reversed to create the north oriented Encampment River drainage route. The Encampment River flow reversal occurred either when a much deeper south oriented valley eroded headward along the North Platte River alignment or when flood flow on the North Platte River alignment was reversed to create the north-northwest oriented North Platte River drainage route.

Detailed location map for Encampment River-Elk River drainage divide area

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

Figure 2 provides a more detailed location map for the Encampment River-Elk River drainage divide area in the Wyoming and Colorado Sierra Madre Mountains and Park Range. The Wyoming-Colorado state line extends in a west to east direction across figure 2 (north of center). The east-west continental divide is shown with a dashed line extending from the north edge of figure 2 (west half) to the south center edge of figure 2. Green colored areas are National Forest lands, which in this region are usually located in mountainous areas. The Sierra Madre Mountains are labeled and are located along the continental divide north and south of the state line. The Park Range is located south of the Sierra Madre Mountains and extends in a south direction from the south center edge of figure 2. Walden is a town near the southeast corner of figure 2. The North Platte River is formed west of Walden at the confluence of its south, northeast, and southeast oriented North Fork and of its southeast and northeast oriented Roaring Fork. Once formed the North Platte River flows in a north direction to near the state line and then flows in a north-northwest direction to the north edge of figure 2 (just east of the Beaver Creek Hills). Encampment is a town near the north center edge of figure 2. The Encampment River originates in northern Colorado and flows in a north direction to Encampment and north of figure 2 joins the north-northwest oriented North Platte River. East of the Encampment River headwaters are headwaters of northeast oriented South Fork Big Creek, which turns in a northwest direction to join southeast oriented North Fork Big Creek and northeast oriented Beaver Creek and to form northeast and north oriented Big Creek, which flows to the north-northwest oriented North Platte River. South of the South Fork Big Creek headwaters and east of the Encampment River headwaters are east oriented headwaters of the south oriented North Fork North Platte River. South of the north oriented Encampment River headwaters and on the south side of the continental divide are north and west oriented headwaters of the southwest and south oriented North Fork Elk River, which flows to the southwest and south oriented Elk River with the Elk River flowing to the south edge of figure 2 (west of center). South of figure 2 the Elk River flows to the west oriented Yampa River, which flows to the south oriented Green River with water eventually reaching the Colorado River and Pacific Ocean. West of the North Fork Elk River headwaters are headwaters of the northwest oriented Middle Fork Little Snake River, which flows to the west oriented Little Snake River, which then flows near the Wyoming-Colorado state line. West of figure 2 the Little Snake River turns to flow in a southwest direction to join the west oriented Yampa River. Barbed tributaries, elbows of capture, and drainage route U-turns are common in the Encampment River-Elk River drainage divide area. Generally north oriented drainage routes originated as south oriented flood flow channels and were subsequently beheaded by headward erosion of much deeper valleys. Floodwaters on north ends of the beheaded flood flow channels then reversed flow direction to create north oriented drainage routes. Headward erosion of the much deeper valleys beheaded the south oriented flood flow channels one at a time, which meant reversed flood flow could be flowing in a north direction on a newly beheaded and reversed flood flow channel while floodwaters were still flowing in a south direction on an adjacent flood flow channel a situation that helped create present-day drainage route U-turns.

Hog Park Creek-Middle Fork Little Snake River drainage divide area

Figure 3: Hog Park Creek-Middle Fork Little Snake River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of Hog Park Creek-Middle Fork Little Snake River drainage divide area. The map contour interval for figure 3 is 50 meters. The east-west continental divide is shown with a labeled dashed line extending from the north edge of figure 3 (west of center) to the south edge of figure 3 (east half). The Encampment River flows in a north, northwest, and northeast direction from the east edge of figure 3 (south half) to the north edge of figure 3 (east half) and north of figure 3 flows in a north direction to join the north-northwest oriented North Platte River with water eventually reaching the Gulf of Mexico. The West Fork Encampment River originates near West Fork Lake (near southeast corner of figure 3) and flows in a west and north direction to join the Encampment River (near the state line). Hog Park Creek originates near the north edge of figure 3 (near continental divide and flows to Hog Park Reservoir before flowing in a southeast and northeast direction to join the Encampment River at the point where the Encampment River turns to flow in a northeast direction. The South Fork Hog Park Creek originates near the continental divide (near south edge of figure 3) and flows in a north direction to join Hog Park Creek at the point where Hog Park Creek turns to flow in a northeast direction. South of the South Fork Hog Park Creek headwaters and south of the continental divide are headwaters of the northwest oriented Middle Fork Little Snake River, which flows to the west center edge of figure 3. West of figure 3 the Middle Fork flows to the west and southwest oriented Little Snake River with water eventually reaching the Colorado River and Pacific Ocean. Whiskey Creek is a south oriented Middle Fork Little Snake River tributary originating south of Hog Park Reservoir (and south of the continental divide). Through valleys link the south oriented Whiskey Creek valley with the Hog Park Creek valley and the north oriented South Fork Hog Park Creek valley with the Middle Fork Little Snake River headwaters valley. The floor elevation of the Hog Park Creek-Whiskey Creek through valley is between 2750 and 2800 meters. West of the through valley elevations rise to at least 3000 meters and east of the through valley elevations rise to 2920 meters. These elevations suggest the through valley is at least 120 meters deep. The South Hog Park Creek-Middle Fork Little Snake River through valley floor elevation is between 2800 and 2850 meters. Elevations east of the through valley rise to more than 3150 meters. Depending on which adjacent elevations are used the through valley is between 70 and 150 meters deep, if not deeper. These through valleys were eroded by south oriented flood flow channels prior to the reversal of flood flow on the Encampment River alignment. The southeast-northeast oriented Hog Park Creek elbow of capture originated where a southeast oriented flood flow channel converged with a southwest oriented flood flow channel to form a south oriented flood flow channel on the South Fork Hog Park Creek alignment. The reversal of flood flow on the Encampment River alignment reversed flood flow on the south oriented flood flow channel and captured southeast oriented Hog Park Creek headwaters flow to create the present day southeast and northeast oriented Hog Park Creek and the north oriented South Fork Hog Park Creek drainage routes.

Detailed map of Hog Park Creek-Whiskey Creek drainage divide area

Figure 4: Detailed map of Hog Park Creek-Whiskey 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 Hog Park Creek-Whiskey Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 40 feet. The east-west continental divide is shown with a labeled dashed line extending from the north edge of figure 4 (west half) to the east edge of figure 4 (south half). Hog Park Creek flows in an east direction from the north edge of figure 4 (east of the continental divide) to Hog Park Reservoir where Hog Park Creek makes a southeast and northeast jog before flowing in a southeast direction to the east edge of figure 4. East of figure 4 Hog Park Creek flows in a southeast and northeast direction to join the north oriented Encampment River, which then flows to the north-northwest oriented North Platte River with water eventually reaching the Gulf of Mexico. Whiskey Creek originates in section 13 (south of the continental divide) and flows in a south-southwest direction to the south center edge of figure 4. South of figure 4 Whiskey Creek flows to the northwest oriented Middle Fork Little Snake River, which flows to the west and southwest oriented Little Snake River with water eventually reaching the Colorado River and Pacific Ocean. A through valley in the northwest quadrant of section 13 links the valley of a northeast oriented Hog Park Creek tributary with the south oriented Whiskey Creek valley. The through valley floor elevation is between 9080 and 9120 feet. The elevation in the northwest quadrant of section 14 to the west rises to 9718 feet. Elevations in the west half of section 18 rise to 9506 feet and south and east of figure 4 elevations rise to at least 9765 feet. Based on elevations seen in figure 4 the through valley is almost 400 feet deep. Using the more distant elevations the through valley is approximately 600 feet deep. Regardless of how deep the through valley is the through valley was eroded by south oriented flood flow moving from the present day Hog Park Creek drainage basin to the Middle Fork Little Snake River drainage basin. Headward erosion of the southeast oriented Hog Park Creek valley (probably from a south oriented flood flow channel on the present day north oriented South Fork Hog Park Creek alignment) and its northeast oriented tributary valley captured the south oriented flood flow and diverted the floodwaters from the developing Middle Fork Little Snake River drainage system to the south oriented flood flow channel on the present day north oriented South Fork Hog Park Creek alignment. Subsequently flood flow on the Encampment River alignment was beheaded and reversed to create the present day north oriented Encampment River drainage route and captured the Hog Park Creek drainage route.

Encampment River-North Fork Elk River drainage divide area

Figure 5: Encampment River-North Fork Elk River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the Encampment River-North Fork Elk River drainage divide area south 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 east-west continental divide is shown with a labeled dashed line extending from the north edge of figure 5 (near northwest corner) to the south edge of figure 5 (east half). The Encampment River (labeled “River” in figure 5) originates north of the continental divide in the southeast quadrant of figure 5 and flows in a north-northwest direction to the north center edge of figure 5. North of figure 5 the Encampment River flows to the north-northwest oriented North Platte River with water eventually reaching the Gulf of Mexico. The West Fork Encampment River originates near West Fork Lake (near center of figure 5) and flows in a west and north direction to the north edge of figure 5 (west of center) and joins the Encampment River north of figure 5. South Fork Hog Creek originates just north of the continental divide in the northwest quadrant of figure 5 and flows in a north direction to the north edge of figure 5 (west half). North of figure 5 South Fork Hog Park Creek flows to northeast oriented Hog Park Creek, which flows to the north oriented Encampment River. The North Fork Elk River (labeled “Fork” in figure 5) originated at the south edge of figure 5 (just west of the continental divide) and flows in a north, west, and southwest direction to the south center edge of figure 5. South of figure 5 the North Fork flows in a south direction to join the southwest and south oriented Elk River, which then flows to the west oriented Yampa River with water eventually reaching the Colorado River and Pacific Ocean. Trail Creek is a south oriented North Fork Elk Creek tributary originating south of the continental and south of the north oriented West Fork Encampment River segment. Silver City Creek originates west of Dome Peak (in southwest quadrant of figure 5) and flows in a northwest direction to join the northwest oriented Middle Fork Little Snake River in Big Red Park near the west center edge of figure 5. West of the figure the Middle Fork Little Snake River flows to the west and southwest oriented Little Snake River, which flows to the west oriented Yampa River. Figure 5 is remarkable as a maze of through valleys link the various drainage routes and describe what was once a large-scale south oriented anastomosing channel complex. One of the deepest through valleys links the north oriented Encampment River headwaters valley with the valley of a south oriented North Fork Elk River tributary. The through valley floor elevation is between 2950 and 3000 meters. Buck Mountain to the west rises to more than 3400 meters and the unnamed mountain to the east rises to more than 3450 meters. These elevations suggest the through valley is more than 400 meters deep. The West Fork Encampment River-Trail Creek through valley also has a floor elevation of between 2950 and 3000 meters. Dome Peak to west rises to more than 3200 meters while Buck Mountain to the west rises to more than 3400 meters suggesting the through valley is at least 200 meters deep. The West Fork-Encampment River through valley is more than 400 meters deep and the Silver City Creek-Middle Fork Little Snake River through valley is at least 250 meters deep. These and other through valleys seen in figure 5 were all eroded by south oriented flood flow prior to the beheading and reversal of those flood flow channels.

Detailed map of Encampment River-North Fork Elk River drainage divide area

Figure 6: Detailed map of Encampment River-North Fork Elk River 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 Encampment River-North Fork Elk River drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. The east-west continental divide serves as the Jackson-Routt County line and is shown with a labeled dashed line extending from the west edge of figure 6 (north half-not far from northwest corner) to the south edge of figure 6 (near southeast corner). The Encampment River originates near the center of figure 6 (north of the continental divide) and flows in a north and north-northwest direction to the north edge of figure (west of center). North of figure 6 the Encampment River flows to the north-northwest oriented North Platte River with water eventually reaching the Gulf of Mexico. The North Fork Elk River flows in north and west direction from the south edge of figure 6 (east half) before turning to flow in a southwest direction through Diamond Park to the southwest corner of figure 6. South and west of figure 6 the North Fork Elk River flows to the south oriented Elk River, which flows to the west oriented Yampa River with water eventually reaching the Colorado River and Pacific Ocean. A deep north to south oriented through valley or pass in the northwest corner of section 3 links the north oriented Encampment River valley with the valley of a south oriented North Fork Elk River tributary. The through valley floor elevation is between 9800 and 9840 feet. Buck Mountain in section PB 38 to the west rises to 11,396 feet and elevations on the east border of section 2 to the east rise to 11,429 feet. These elevations suggest the through valley is at least 1500 feet deep. The through valley was eroded by south oriented flood flow moving from the present day north oriented Encampment River alignment to the south oriented Elk River valley. South oriented flood flow on the Encampment River had to come from south oriented flood flow on the present day north oriented North Platte River alignment so the evidence seen here in figure 6 is proof of flood flow reversals in both the Encampment River valley and the North Platte River valley. Alpine glacial landforms are present in figure 6 as are small remnants of the former alpine glaciers. This evidence suggests alpine glaciers have modified some of the valleys seen in figure 6. However, the valleys were eroded prior to the glaciation, which filled pre-existing valleys with ice. The glaciation occurred after all flood flow across the region had ended and after the Park Range had emerged as a high mountain range and did not correlate with the thick ice sheet melt down that produced the immense melt water floods responsible for erosion of the deep valleys seen in figure 6.

South Fork Big Creek-North Fork North Platte River drainage divide area

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

Figure 7 illustrates the South Fork Big Creek-North Fork North Platte River drainage divide area east and slightly north of figure 5 and includes a large overlap area with figure 5. The map contour interval for figure 7 is 50 meters. The east-west continental divide is shown with a labeled dashed line extending from the west center edge of figure 7 to the south center edge of figure 7. The North Fork Elk River flows in a north, west, and southwest direction near the south edge of the southwest quadrant of figure 7. South of figure 7 the North Fork flows to the southwest and south oriented Elk River with water eventually reaching the Colorado River and Pacific Ocean. Trail Creek is the south oriented stream originating near the continental divide and flowing to the south edge of figure 7 (near southwest corner). South of figure 7 Trail Creek joins the southwest and south oriented North Fork Elk River.  The Encampment River flows in a north-northwest direction from near the continental divide in the southwest quadrant of figure 7 to the northwest corner of figure 7. North of figure 7 the Encampment River flows in a north direction to join the north-northwest oriented North Platte River with water eventually reaching the Gulf of Mexico. The South Fork Big Creek originates north of the south center edge of figure 7 and east of the continental divide and flows in a north-northeast, northeast, north, and northeast direction to near the northeast corner of figure 7. North and east of figure 7 Big Creek joins the north-northwest oriented North Platte River. The North Fork North Platte River originates in the southeast quadrant of figure 7 (east of Red Elephant Mountain) and flows in an east, southeast, and south direction to near the southeast corner of figure 7. South of figure 7 the North Fork North Platte River flows in a south, northeast, and southeast direction before joining the Roaring Fork to form the north and north-northwest oriented North Platte River. The North Fork North Platte River is a classic barbed tributary and provides evidence the direction of flow in the North Platte River valley has been reversed. A through valley links the North Fork North Platte River with the northeast oriented South Fork Big Creek valley. The through valley floor elevation is between 2800 and 2850 meters and elevations to the east rise to at least 2900 meters suggesting the through valley is at least 50 meters deep. The through valley provides evidence of a south oriented flood flow channel from the present day north oriented South Fork Big Creek alignment to the south oriented North Fork North Platte River valley.

Detailed map of South Fork Big Creek-North Fork North Platte River drainage divide area

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

Figure 8 provides a detailed topographic map of the South Fork Big Creek-North Fork North Platte River drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 20 feet in the eastern two-thirds and 40 feet in the western third. The South Fork Big Creek flows in a northeast direction from the west edge of figure 8 (south half) to the Big Creek Lakes and after flowing in a north direction through Big Creek Lakes the South Fork Big Creek then drains to the north center edge of figure 8. North of figure 8 the South Fork Big Creek flows in a northeast and northwest direction to join northeast and north oriented Big Creek, which flows to the north-northwest oriented North Platte River. The North Fork North Platte River originates in the south half of section 29 (in southwest quadrant of figure 8) and flows in an east and southeast direction to the southeast corner of figure 8. South of figure 8 the North Fork North Platte River flows in a south direction before finally turning in a northeast and southeast direction to join the Roaring Fork and to form the north and north-northwest oriented North Platte River. A through valley near the corner of sections 21, 22, 27, and 28 links the northeast and north oriented South Fork Big Creek valley with the southeast and south oriented North Fork North Platte River valley. The through valley floor elevation is between 9200 and 9220 feet. Elevations east of the through valley rise to 9505 feet and west of the through valley elevations rise much higher. These elevations suggest the through valley is approximately 300 feet deep. The through valley was eroded by south oriented flood flow moving from the present day north oriented South Fork Big Creek valley in the Big Creek Lakes region to the southeast and south oriented North Fork North Platte River valley. At the time the through valley was eroded flood flow was moving in a south direction on the present day north and north-northwest oriented North Platte River alignment and probably also on the present day north oriented Encampment River alignment. South oriented flood flow to the Big Creek Lakes area was beheaded and reversed by headward erosion of deeper valleys across the south oriented flood flow channel (north of figure 8). The deeper valley may have been a south oriented valley eroded by south oriented flood flow or it may have been a deeper north oriented valley after the flood flow reversal on the North Platte River alignment. In the first case it is probable that south oriented flood flow on the Encampment River alignment flowed in an east direction to the Big Creek Falls area (near southwest corner of section 20) and then in a northeast, north, and northeast direction to erode the deeper northeast, north, and northeast oriented South Fork Big Creek valley, which beheaded the south oriented flood flow channel to the North Fork North Platte River valley. If so the Big Creek Falls knick point may have eroded headward rapidly until that flood flow ended. Since that time knick point headward erosion has been much slower. The lakes suggest the region has been glaciated, and while glaciers may have filled and altered some of the valleys the glaciers did not erode new valleys or change valley orientations.

Middle Fork Big Creek-Damfino Creek drainage divide area

Figure 9: Middle Fork Big Creek-Damfino Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Middle Fork Big Creek-Damfino Creek drainage divide area north and slightly west 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 south half of figure 9. The entire region seen in figure 9 is east of the east-west continental divide. The Encampment River flows in a north, northwest, north-northwest, and north-northeast direction from the south edge of figure 9 (west half) to the north edge of figure 9 (west half) and north of figure 9 flows to the north-northwest oriented North Platte River. The East Fork Encampment River originates just south of the word “FOREST” and flows in a south-southwest, west, and northwest direction to join a northwest oriented segment of the north oriented Encampment River. Coon Creek is a southwest oriented tributary to the south-southwest oriented East Fork segment. Damfino Creek is a west and northwest oriented stream near the state line flowing to the west and northwest oriented East Fork Encampment River segment. West of the Damfino Creek headwaters and just north of the state line are headwaters of northeast, southeast, and northeast oriented Middle Fork Big Creek, which flows to the east center edge of figure 9. East of figure 9 the Middle Fork joins the South Fork to form northeast and north oriented Big Creek, which flows to the north-northwest oriented North Platte River. South of the elbow of capture where the Middle Fork turns from flowing in a southeast direction to flowing in a northeast direction there is a southeast oriented through valley with the town of Pearl being located in the through valley near the east edge of figure 9 (south half). South and east of Pearl the southeast oriented through valley is linked to the south oriented Lake Creek valley with Lake Creek flowing to the North Fork North Platte River. Northeast oriented South Fork Big Creek is the stream flowing across the southeast corner of figure 9 near Pearl. A through valley links the west oriented Damfino Creek valley with the east oriented Middle Fork Big Creek valley. The through valley floor elevation is between 2900 and 2950 meters. Blacktail Mountain to the north rises to 3345 meters. Buffalo Ridge to the south rises to more than 3300 meters. These elevations suggest the Damfino Creek-Middle Fork Big Creek through valley is more than 300 meters deep. The through valley was probably eroded by southeast and east oriented flood flow from a south oriented flood flow channel on the present day north oriented Encampment River alignment moving to the southeast oriented Middle Fork Big Creek valley. Floodwaters then continued in a southeast direction to the south oriented Lake Creek valley. Headward erosion of the northeast oriented South Fork Big Creek valley and subsequently of the northeast oriented Middle Fork Big Creek valley captured the southeast and south oriented flood flow and diverted the floodwaters to the much deeper North Platte River valley (which still may have been a south oriented flood flow channel at that time).

Middle Fork Big Creek-Lake Creek drainage divide area

Figure 10: Middle Fork Big Creek-Lake Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a topographic map of the Middle Fork Big Creek-Lake Creek drainage divide area south and east of figure 9 and includes an overlap area with figure 9. The map contour interval for figure 10 is 50 meters, although there appears to be a mislabeled contour line in the center region of figure 10 (the 3000-meter contour line should probably read 2750 meters). The west to east oriented state line extends across the north half of figure 10. The North Platte River flows in a north direction from the southeast corner of figure 10 and turns in a northwest direction to flow across the northeast corner of figure 10. Big Creek Lakes are located near the southwest corner of figure 10. The South Fork Big Creek flows in a northeast direction from Big Creek Lakes to near the town of Pearl and then flows in a north and northwest direction to join the northeast oriented Middle Fork near the north edge of figure 10 and to form northeast and north oriented Big Creek, which north of figure 10 joins the north-northwest oriented North Platte River. The Middle Fork Big Creek flows in a northeast and southeast direction from the west edge of figure 10 (near northwest corner) before turning to flow in a north and northeast direction to join the South Fork and to form Big Creek. A northwest to southeast oriented through valley extending from the Middle Fork elbow of capture to the town of Pearl links the Middle Fork valley with the South Fork valley. The through valley floor elevation is between 2550 and 2600 meters. Elevations east of the through valley rise to more than 2700 meters suggesting the through valley is at least 100 meters deep (west of the through valley elevations rise much higher than 2700 meters). The road going south from Pearl uses a through valley linking a north oriented South Fork Big Creek tributary valley with the south oriented Lake Creek valley. This South Fork Big Creek-Lake Creek through valley has a floor elevation of between 2550 and 2600 meters. Assuming the 3000-meter contour line to the east should read 2750 meters elevations to the east rise to at least 2950 meters. Elevations to the west also rise to at least 2950 meters suggesting the through valley is at least 300 meters deep. This southeast and south oriented through valley was eroded by a southeast and south oriented flood flow channel. The north oriented South Fork Big Creek valley segment north of Pearl was probably initiated by a south oriented flood flow channel that converged with the southeast and south oriented flood flow channel in the present day through valley leading to the Lake Creek valley. Study of the region seen in figure 10 reveals evidence of what were other converging and diverging flood flow channels in what was a large-scale south oriented anastomosing channel complex, which included the Encampment River valley and its tributary valleys located west of figure 10 and seen in earlier figures. Uplift of the Sierra Madre Mountains and Park Range and of the entire region and headward erosion of much deeper valleys to the north of the study region resulted in systematic reversals of the flood flow to form the present day north oriented North Platte River drainage route and tributary system.

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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