Abstract:

This essay uses topographic map evidence to interpret landform origins in the Grizzly Creek-Colorado River drainage divide area in the Colorado Rabbit Ears Range. The Rabbit Ears Range is a west to east oriented mountain range separating the north oriented North Platte River headwaters area in North Park from the deep west and southwest oriented Colorado River valley. Water in the Colorado River eventually reaches the Pacific Ocean. Grizzly Creek is a north oriented North Platte River tributary draining much of the southwest quadrant of North Park to the north oriented North Platte River with water eventually reaching the Platte, Missouri, and Mississippi Rivers and the Gulf of Mexico. North oriented Grizzly Creek headwaters and tributary valleys are linked by through valleys or passes across the continental divide with south oriented Colorado River tributary valleys. In addition north to south oriented through valleys or passes link Grizzly Creek tributary valleys with each other and north oriented Grizzly Creek is joined by southeast oriented barbed tributaries. The through valleys (or passes), barbed tributaries, and valley orientations are interpreted in the context of immense melt water floods that once flowed across the region. At the time floodwaters crossed the region mountain ranges were beginning to emerge and the deep west and southwest oriented Colorado River valley was in the process of being eroded headward into the region. Floodwaters were derived from the western margin of a thick North American ice sheet and were flowing from western Canada to and across the region. 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 Park region. Prior to headward erosion of the deep west and southwest oriented Colorado River valley floodwaters flowed across region  and then to and across the present day Front Range location to what are today southeast oriented valleys draining to the north oriented South Platte River. The present day north oriented North Platte River drainage route originated as a major south oriented flood flow channel (or channels) between emerging mountain ranges. Headward erosion of the deep Colorado River valley first captured the flood flow and diverted the floodwaters in a southwest direction. Floodwaters on the north end of the beheaded flood flow channel(s) reversed flow direction to create the north oriented Blue River drainage route. The Blue River flood flow reversal was probably greatly aided by Front Range uplift, which occurred as floodwaters flowed across it. Subsequently similar flood flow reversals created the north oriented North Platte River and Grizzly Creek drainage routes and ended all south oriented flood flow from North Park to the newly eroded Colorado River valley

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 Grizzly Creek-Colorado River drainage divide area landform origins in the Colorado Rabbit Ears 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 Grizzly Creek-Colorado River drainage divide area landform evidence in the Colorado Rabbit Ears Range will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Grizzly Creek-Colorado River drainage divide area location map

Figure 1: Grizzly Creek-Colorado 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 Grizzly Creek-Colorado River drainage divide area in the Colorado Rabbit Ears Range and illustrates a region in north central Colorado with Wyoming to the north of Colorado. Rocky Mountain National Park is located east of the center of figure 1. Rabbit Ears Pass is located west of Rocky Mountain National Park and the Rabbit Ears Range (not labeled in figure 1) extends in a west to east direction from Rabbit Ears Pass to near Rocky Mountain National Park. The Colorado River flows from the southwest corner of Rocky Mountain National Park in a southwest direction to the southwest corner of figure 1 and south and west of figure 1 eventually reaches the Pacific Ocean. The Medicine Bow Mountains extend in a north-northwest direction from the northwest corner of Rocky Mountain National Park into Wyoming. The Laramie River flows in a north direction along the east side of the Medicine Bow Mountains as it enters Wyoming. The Park Range is a north to south oriented mountain range north of Rabbit Ears Pass. The region between the Park Range and the southern Medicine Bow Mountains is known as North Park (not labeled in figure 1). The north oriented river draining North Park and flowing from Cowdrey to the north center edge of figure 1 is the North Platte River. North of figure 1 in central Wyoming the North Platte River flows in a north direction around the northwest end of the Laramie Mountains and then in a southeast direction to flow into Nebraska with water eventually reaching the Platte, Missouri, and Mississippi Rivers and the Gulf of Mexico. Grizzly Creek is only partially shown in figure 1 and is not labeled, but is the north oriented stream flowing to the North Platte River near Coalmont and drains the western Rabbit Ears Range northern slope. Note how the north-northwest oriented Blue River joins the Colorado River at Kremmling just south of an unlabeled south oriented Colorado River tributary (Muddy Creek on more detailed maps). The south oriented Colorado River tributary originates just south of the Grizzly Creek headwaters. The Grizzly Creek-Colorado River drainage divide area along the continental divide in the Colorado Rabbit Ears Range investigated in this essay is located east of Rabbit Ears Pass and extends eastward to near Parkview Mountain.

Immense melt water floods flowing from the western margin of a thick North American ice sheet in western Canada to the actively eroding Colorado River valley and its south oriented tributary valleys eroded the Rabbit Ears Range and other mountain ranges seen in figure 1. At that time the mountain ranges were beginning to emerge and at first floodwaters could flow across what are today high mountain barriers. Mountain ranges emerged as floodwaters deeply eroded the surrounding basins and valleys and as ice sheet related crustal warping raised the mountain ranges and also raised the entire region seen in figure 1. The present day north oriented Laramie River and North Platte River drainage routes seen in figure 1 originated as south oriented flood flow channels supplying floodwaters to actively eroding Colorado River valley and its tributary valleys. Headward erosion of a much deeper northeast oriented valley(s) across the Laramie Mountains (north of figure 1) beheaded the south oriented flood flow channel on the present day north oriented Laramie River alignment. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow in a north direction to the much deeper east oriented valley and to create the north and northeast oriented Laramie River drainage route. The reversal of flood flow on the Laramie River alignment also captured south oriented flood flow still moving on the present day north oriented North Platte River alignment. The captured flood flow made a U-turn around the south end of the Medicine Bow Mountains to flow from North Park to the newly formed north oriented Laramie River drainage route. Subsequently headward erosion of the deep southeast oriented North Platte River valley around the northwest end of the Laramie Mountains (in central Wyoming-north of figure 1) beheaded the south oriented flood flow channel(s) on the present day north oriented North Platte River alignment. Floodwaters on the north end of the beheaded flood flow channel(s) reversed flow direction to create the north and southeast oriented North Platte River drainage route. The massive flood flow reversals were greatly aided by ice sheet related crustal warping that was raising the North Park region and the surrounding mountain ranges.

Detailed location map for Grizzly Creek-Colorado River drainage divide area

Figure 2: Detailed location map Grizzly Creek-Colorado 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 Grizzly Creek-Colorado River drainage divide area in the Colorado Rabbit Ears Range. Green colored areas are National Forest lands and in this region are generally located in mountainous regions. The east-west continental divide is shown with a dashed line extending from the north edge of figure 2 (west half) in a south direction to Rabbit Ears Pass and then in an east direction along the Rabbit Ears Range crest to the east edge of figure 2 (slightly south of center). The stream originating near Rabbit Ears Pass and flowing in a south-southeast, east, and south-southeast direction to the south center edge of figure 2 is Muddy Creek, which south of figure 2 flows to the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. East of Muddy Creek the south oriented stream originating near the continental divide and flowing to the south edge of figure 2 (east of center) is Troublesome Creek, which south of figure 2 also flows to the Colorado River. The East Fork Troublesome Creek originates south of the continental divide between Sheep Mountain and Parkview Mountain and flows in a southwest and south-southwest direction to join Troublesome Creek near the south edge of figure 2. Grizzly Creek originates near Rabbit Ears Pass and flows in a northeast and north-northeast direction to the north edge of figure 2 (slightly east of center). North of figure 2 Grizzly Creek flows to the north oriented North Platte River with water eventually reaching the Gulf of Mexico. Colorado Creek is an east-northeast and southeast oriented Grizzly Creek tributary originating north of Rabbit Ears Pass. Little Grizzly Creek originates north of the Colorado Creek headwaters and flows in a north, east-northeast, and northeast direction to the north center edge of figure 2 and joins Grizzly Creek north of figure 2. Arapahoe Creek is a northwest oriented stream originating near Hyannis Peak (on the continental divide near center of figure 2) and joining Grizzly Creek south of the town of Spicer. Lost Creek is a north and northwest oriented Grizzly Creek tributary located north and east of Arapahoe Creek. The Illinois River flows in a northwest and north-northwest direction from the east center edge of figure 2 (just north of the continental divide) to the north edge of figure 2 (east half) and north of figure 2 joins the north oriented North Platte River. Note unlabeled northeast oriented Illinois River tributaries originating near the continental in the region between Hyannis Peak and Parkview Mountain. Steamboat Springs is the town located in the northwest quadrant of figure 2. The Yampa River flows in a northeast, and north direction from the west edge of figure 2 to Steamboat Springs and then turns to flow in a west direction to the west edge of figure 2 (north half). West of figure 2 the Yampa River flows to the south oriented Green River, which then flows to the southwest oriented Colorado River. The north oriented Yampa River segment was created by a reversal of flood flow on the north end of a south oriented flood flow channel, which was beheaded by headward erosion of the much deeper west oriented Yampa River valley.

Little Grizzly Creek-Colorado Creek drainage divide area

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

Figure 3 provides a topographic map of Little Grizzly Creek-Colorado Creek drainage divide area. The map contour interval for figure 3 is 50 meters. The east-west continental divide serves as the county line and is shown with a labeled dashed line extending in a south direction along the south end of the Park Range from near the northwest corner of figure 3 to the south edge of figure 3 (west half). Rabbit Ears Pass is located on the continental divide just south of figure 3. West of the continental divide drainage routes flow to the north and west oriented Yampa River with water eventually reaching the Green and Colorado Rivers and Pacific Ocean. Grizzly Creek flows from the south edge of figure 3 (near highway) to the east edge of figure 3 (near highway). North of figure 3 Grizzly Creek flows to the north oriented North Platte River with water eventually reaching the Mississippi River and Gulf of Mexico. Arapahoe Creek is the northwest oriented stream joining Grizzly Creek near the southeast corner of figure 3. Colorado Creek is the east, south, east, and southeast oriented (and barbed) Grizzly Creek tributary flowing through the Cloverleaf Valley (in the south center area of figure 3). Mexican Ridge is the northwest to southeast oriented ridge north and east of Colorado Creek. Mexican Creek is southeast oriented stream located north and east of Mexican Ridge joining north oriented Grizzly Creek as a barbed tributary. Little Grizzly Creek flows in an overall east direction with northeast and southeast jogs near and across the north edge of figure 3 from near the continental divide in the northwest quadrant of figure 3 to join northeast oriented Chedsey Creek, which joins Grizzly Creek north and east of figure 3. Doran Creek is the north oriented Little Grizzly Creek tributary west of Mexican Ridge and Crosby Creek is an east and north-northeast oriented Doran Creek tributary. Sawmill Creek is a north oriented Little Grizzly Creek tributary north and west of Crosby Creek. A north to south oriented through valleys link the north oriented Doran Creek valley with the south, east, and southeast oriented Colorado Creek valley. The through valley floor elevation is between 2650 and 2700 meters. Mexican Ridge to the east rises to 2854 meters and much higher elevations are located west of the through valley along the continental divide. These elevations suggest the through valley is at least 158 meters deep. The through valley and a similar through valley linking the north oriented Sawmill Creek valley with the Crosby Creek valley were eroded by south oriented flood flow prior to headward erosion of the deeper east oriented Little Grizzly Creek valley. Headward erosion of the Little Grizzly Creek valley captured the flood flow routes and floodwaters on north ends of the beheaded flood flow routes reversed flow direction to create the north oriented Doran Creek and Sawmill Creek drainage routes. The flood flow reversals may have been aided by crustal warping that was raising the Doran and Sawmill Creek headwaters areas.

Detailed map of Doran Creek-Colorado Creek drainage divide area

Figure 4: Detailed map of Doran Creek-Colorado 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 Doran Creek-Colorado Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet except near the west edge where the contour interval is 40 feet. Colorado Creek flows in a north-northeast and east-northeast direction from the southwest corner of figure 4 to near the east edge of section 22 where Colorado Creek turns to flow in a south-southeast, east, and south-southeast direction to the southeast corner of figure 4. South and east of figure 4 Colorado Creek flows in a south direction to join east and north oriented Grizzly Creek with water eventually reaching the north oriented North Platte River. Doran Creek originates in section 15 as a southeast oriented stream, but quickly turns to flow in a north direction to the north center edge of figure 4. North of figure 4 Doran Creek flows to northeast, southeast, and northeast oriented Little Grizzly Creek with water eventually reaching Grizzly Creek and the North Platte River. A through valley in the northwest corner of section 23 links the north oriented Doran Creek valley with a southeast oriented Colorado Creek tributary valley. The through valley floor elevation is between 8720 and 8740 feet. Elevations east of the through valley rise to 9383 feet. Elevations along the west margin of figure 4 exceed 9400 feet suggesting the through valley is at least 600 feet deep. Other through valleys can be seen in figure 4. For example, Crosby Creek flows in an east direction from the west edge of figure 4 (north of center) into section 16 where it turns to flow in a north-northeast direction to the north edge of figure 4 (slightly west of center) and north of figure 4 joins Doran Creek. A through valley (along the line between sections 15 and 16) links the Crosby Creek valley (at its elbow of capture) with the southeast oriented Doran Creek headwaters valley. The through valley floor elevation is between 8880 and 8900 feet Elevations in the northwest corner of section 15 rise to 9175 feet and elevations in the southwest quadrant of section 16 rise to 9451 feet. These elevations suggest the through valley is at least 275 feet deep. The Crosby Creek-Doran Creek and the Doran Creek-Colorado Creek through valleys were eroded by a southeast oriented flood flow channel prior to the reversal of south oriented flood flow on the present day north oriented Doran Creek alignment, which occurred prior to the reversal of flood flow on the present day north-northeast oriented Crosby Creek alignment. Apparently significant floodwaters came from west of figure 4 as Crosby Creek has since eroded its valley almost 100 feet deeper than the through valley.

Grizzly Creek-Little Muddy Creek drainage divide area

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

Figure 5 illustrates the Grizzly Creek-Little Muddy Creek drainage divide area south and slightly 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 serves as the Jackson-Grand County line and is shown with a labeled dashed line extending from the north edge of figure 5 (west half) to the east edge of figure 5 (south of center). Rabbit Ears Peak is a labeled high point in the northwest quadrant of figure 5. Grizzly Creek originates near Rabbit Ears Peak and flows in a southeast direction before turning to flow in a northeast, east, and north direction to the north edge of figure 5 (east half). North of figure 5 Grizzly Creek flows in a north direction to join the north oriented North Platte River with water eventually reaching the Platte, Missouri, and Mississippi Rivers and Gulf of Mexico. Arapahoe Creek is the northwest oriented Grizzly Creek tributary flowing across the northeast corner of figure 5. A highway intersection is located at a pass across the continental divide near where Grizzly Creek turns from flowing in a southeast direction to flowing in a northeast direction. On more detailed maps the pass is named Muddy Pass. Little Muddy Creek originates near Muddy Pass and flows in a southeast direction to join Muddy Creek near the south center edge of figure 5. Muddy Creek originates west of Rabbit Ears Peak and west of the continental divide and flows in a south direction almost to the south edge of figure 5 before turning to flow in an east, northeast, and southeast direction to the south center edge of figure 5. South of figure 5 Muddy Creek flows in a southeast and south direction to join the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. The north, northwest, and north oriented Blue River valley enters the Colorado River valley directly south of where the southeast and south oriented Muddy Creek valley enters the Colorado River valley. Blue River headwaters and tributary valleys are linked by high-level mountain passes with southeast oriented South Platte River tributary valleys. Muddy Pass has an elevation of between 2600 and 2650 meters. High points east of Muddy Pass exceed 3000 meters and east of figure 5 exceed 3500 meters. Elevations greater than 300 meters can be seen in figure 5 west of Muddy Pass with Rabbit Ears Peak and other high points west of figure 5 exceeding 3200 meters. Depending on which elevations are used Muddy Pass could be considered to be 350 meters to 550 meters deep. However Muddy Pass is viewed it is a major north to south oriented through valley linking the north oriented North Platte River drainage route with a south oriented tributary valley to the southwest oriented Colorado River and also with the present day north, northwest, and north oriented Blue River valley, which links the Muddy Pass through valley with southeast oriented South Platte River tributary valleys draining to the present day north and northeast oriented South Platte River valley. The Muddy Pass through valley was eroded by south oriented flood flow, which was at one time moving from the present day north oriented North Platte River drainage basin across the Rabbit Ears Range and the Colorado Front Range to a south oriented flood flow channel on the present day north oriented South Platte River alignment. Headward erosion of the deep southwest oriented Colorado River valley captured the south and southeast oriented flood flow. Floodwaters on the north and northwest end of the beheaded flood flow channel reversed flow direction to create the present day north, northwest, and north oriented Blue River drainage route. The flood flow reversal was greatly aided by ice sheet related crustal warping that was raising the Colorado Front Range as floodwaters flowed across it. A flood flow reversal on the North Platte River alignment next created the present day north oriented North Platte River and Grizzly Creek drainage routes and ended all flood flow across the emerging Rabbit Ears Range.

Detailed map of Grizzly Creek-Little Muddy Creek drainage divide area

Figure 6: Detailed map of Grizzly Creek-Little Muddy 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 Grizzly Creek-Little Muddy Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet in the south half and 20 feet in the north half. The east-west continental divide serves as a boundary line and is shown with a labeled line extending from the west edge of figure 6 (north of center) to the northeast corner of figure 6. Grizzly Creek flows in a southeast direction from the northwest corner of figure 6 to Muddy Pass Lake and then almost to Muddy Pass before turning to flow in a northeast direction to the north edge of figure 6. North of figure 6 Grizzly Creek makes a jog to the east before turning to flow in a north direction to eventually join the north oriented North Platte River with water eventually reaching the Platte, Missouri, and Mississippi Rivers and Gulf of Mexico. Grizzly Creek tributaries from the northwest are barbed and are oriented in southeast directions while Grizzly Creek tributaries from the southeast are oriented in northwest directions. Little Muddy Creek originates on the south side of Muddy Pass and flows in a south-southeast and southeast direction to the south edge of figure 6 (west of center). South of figure 6 Little Muddy Creek joins southeast and south oriented Muddy Creek, which flows to the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. Muddy Pass has an elevation of 8710 feet. Bear Mountain in section 30 to the east rises to 9846 feet. Baker Mountain to the west rises to 9824 feet. Elevations exceeding 11,000 can be found along the continental divide both east and west (northwest) of figure 6. Based on elevations seen in figure 6 Muddy Pass is at least 1100 feet deep. Using more distant elevations an argument could be made that Muddy Pass is as much as 2300 feet deep. Other north to south oriented passes can be seen crossing the continental divide in figure 6. In the east half of section 25 a deep pass links a northeast and northwest oriented Grizzly Creek tributary valley with a south and southwest oriented Little Muddy Creek tributary valley. Diamond Creek is a southwest oriented Muddy Creek tributary flowing across the southeast corner of figure 6. A south oriented Diamond Creek tributary originates in the east half of section 19 and is linked by through valleys or passes with a northwest oriented Grizzly Creek tributary. These multiple through valleys or passes crossing the present day continental divide were eroded by diverging and converging south oriented flood flow channels prior to the reversal of flood flow that created the north oriented Grizzly Creek and North Platte River drainage route.

Buffalo Creek-Rock Creek drainage divide area

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

Figure 7 illustrates the Buffalo Creek-Rock Creek drainage divide area north and east of figure 5 and includes an overlap area with figure 5 and south and east of figure 3 and includes an overlap area with figure 3. The map contour interval for figure 7 is 50 meters. Grizzly Creek flows in an east and north-northwest direction from the west center edge of figure 5 to near Spicer and then turns to flow in a north-northeast direction to the north edge of figure 7 (west half). North of figure 7 Grizzly Creek flows in a north direction to join the north oriented North Platte River. Arapahoe Creek is the northwest oriented stream flowing to Grizzly Creek near Spicer and is formed near the south edge of figure 7 at the confluence of its northwest oriented Middle and East Forks. Arapahoe Creek flows on the southwest side of Arapahoe Ridge, which extends in a northwest to southeast direction across the south center edge of figure 7. Buffalo Creek originates near the south center edge of figure 7 and flows in a north and north-northwest direction along the west side of Buffalo Ridge before turning to flow in a northwest direction to the north center edge of figure 7. North of figure 7 Buffalo Creek joins north oriented Grizzly Creek. Grassy Run in a northeast and north-northwest oriented Buffalo Creek tributary on the east side of Arapahoe Ridge. East of Grassy Run are headwaters of north-northwest, north-northeast, and northwest oriented Lost Creek, which joins Buffalo Creek north of the north center edge of figure 7. Rock Creek flows in a north and northeast direction from the south edge of figure 7 (just east of Arapahoe Ridge) and then turns in a southeast and northeast and north direction around the south end of Green Ridge to join west and north oriented Willow Creek near the east center edge of figure 7 (Rand is the town near where Rock Creek joins Willow Creek). Willow Creek joins the north-northwest and north oriented Illinois River near the northeast corner of figure 7. North of figure 7 the Illinois River flows roughly in a north direction to eventually join the north oriented Michigan River, which then joins the north oriented North Platte River. Note how the north-northwest oriented Lost Creek headwaters valley is linked by a through valley with the northeast and north-northwest oriented Grassy Run headwaters valley, which is linked by the same through valley with the northeast and southeast oriented Rock Creek valley. The through valley was eroded by south-southeast oriented flood flow moving on the present day north-northwest oriented Buffalo Creek and Lost Creek alignments to the southeast oriented Rock Creek valley where the floodwaters had been captured by a reversal of flood flow east of Green Ridge, which probably occurred prior to the reversal of flood flow on the Grizzly Creek alignment. The northwest and north-northwest oriented Grizzly Creek tributary drainage routes were created by reversals of flood flow on northwest ends of beheaded southeast and south-southeast oriented flood flow channels (diverging from a south oriented flood flow channel on the present day north oriented Grizzly Creek alignment) by headward erosion of a deeper south oriented valley on the Grizzly Creek alignment or could have been created at the time flood flow on the North Platte River and Grizzly Creek alignment was reversed. In either case ice sheet related crustal warping that was raising the Rabbit Ears Range probably greatly assisted in the flood flow reversal process.

Detailed map of Buffalo Creek-Willow Creek drainage divide area

Figure 8: Detailed map of Buffalo Creek-Willow 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 Buffalo Creek-Willow Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 20 feet. Willow Creek flows in a north-northeast and north direction from the east edge of figure 8 (south half) to the north edge of figure 8 (near northeast corner) and north of figure 8 joins the north-northwest oriented Illinois River, which eventually joins the north oriented Michigan River, which then joins the north oriented North Platte River. Buffalo Creek flows in a north direction from the south edge of figure 8 (west of center) to the southeast corner of section 32 and then flows in a north-northwest direction to the north edge of figure 8 (near northwest corner). North and west of figure 8 Buffalo Creek flows in a northwest direction to join north oriented Grizzly Creek, which flows to the north oriented North Platte River. East Buffalo Creek originates near the center of figure 8 and flows in a north-northwest and west direction to join Buffalo Creek in the southwest quadrant of section 20 and which has eroded a 600-foot deep water gap across Buffalo Ridge. Lost Creek flows in a north, north-northeast, and north-northwest direction from the south center edge of figure 8 to the north center edge of figure 8 and north of figure 8 turns in a west-northwest direction to join Buffalo Creek. Buffalo Ridge and Green Ridge appear to be a large hogback ridge crossed by multiple water and wind gaps. The Lost Creek water gap is almost 300 feet deep in figure 8 and is even deeper further to the south. Buffalo Pass in the southeast quadrant of section 20 is a 400-foot deep water gap linking the Lost Creek valley with the East Buffalo Creek valley. An unnamed wind gap near the northwest corner of section 20 is approximately 200 feet deep. A wind gap near the line between sections 28 and 33 links the north-northwest oriented East Buffalo Creek valley with the Lost Creek valley and is more than 100 feet deep. Still other shallower wind gaps are present in the region. The present day north oriented drainage routes and the through valleys defined by the present day wind gaps describe what was once a complex of south oriented diverging and converging flood flow channels which were being eroded into an erosion surface at least as high as the top of Buffalo Ridge and which was probably much higher (at least in relation to present day elevations). Floodwaters were initially flowing in a south direction across the region to south oriented Colorado River tributary valleys south of figure 8. Headward erosion of deeper valleys from the east and ice sheet related crustal warping systematically caused reversals of flood flow as floodwaters eroded deeper and deeper valleys across Buffalo and Green Ridge and surrounding Buffalo and Green Ridge to create the present day north oriented drainage system.

Willow Creek-Haystack Creek drainage divide area

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

Figure 9 illustrates the Willow Creek-Haystack Creek drainage divide area south and east of figure 7 and there is an overlap area with figure 7 and figure 9 is also north and east of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 9 is 50 meters. The east-west continental divide serves as the county line and is shown with a labeled dashed line extending from the west center edge of figure 9 to the east edge of figure 9 (slightly south of center). Arapahoe Ridge is located in the north center area of figure 9 and Hyannis Peak is west of the south end of Arapahoe Ridge. The Middle Fork Arapahoe Creek originates south of Hyannis Peak and flows in a northwest direction to the north edge of figure 9. North of figure 9 the Middle Fork flows to Arapahoe Creek, which then flows to north oriented Grizzly Creek, which flows to the north oriented North Platte River. Little Haystack Mountain is located in the northwest quadrant of figure 9 and the north oriented stream west of Little Haystack Mountain is the South Fork Arapahoe Creek. The north and northeast oriented stream originating near the continental divide and flowing to the northeast corner of figure 9 is Willow Creek. North of figure 9 Willow Creek turns to flow in a northwest, west, and north direction to join the north-northwest oriented Illinois River, which joins the north oriented Michigan River, which then flows to the north oriented North Platte River. The south and southwest oriented stream flowing from the south end of Arapahoe Ridge (on south side of continental divide) is Troublesome Creek, which south of figure 9 flows in a south direction to join the west and southwest oriented Colorado River. Rabbit Ears Creek is the south and southeast oriented stream originating near the continental divide and joining Troublesome Creek just south of the south edge of figure 9. Carter Creek is the south oriented stream west of Rabbit Ears Creek and is a Muddy Creek tributary. The south oriented stream originating south of the north-oriented Willow Creek headwaters is Haystack Creek. South of figure 9 Haystack Creek joins southwest oriented East Fork Troublesome Creek, which then flows to Troublesome Creek. North to south oriented through valleys of varying depths can be seen crossing the continental divide segment seen in figure 9. The deepest and most obvious through valley links the north oriented Willow Creek valley with the south oriented Haystack Creek valley, although numerous less obvious through valleys exist as well. The Willow Creek-Haystack Creek through valley or pass has an elevation of between 3050 and 3100 meters. Elevations along the continental divide to the west rise to more than 3550 meters near the south end of Arapahoe Ridge. Continental divide elevations east of the through valley and seen in figure 9 rise to more than 3500 meters and just east of figure 9 elevations rise more than 3700 meters. These elevations suggest the Willow Creek-Haystack Creek through valley is as much as 400 meters deep and may be even deeper. The through valley and other shallower through valleys seen in figure 9 were eroded by south oriented flood flow moving to actively eroding south oriented Colorado River tributary valleys. Prior to headward erosion of the deep west and southwest oriented Colorado River valley south of figure 9 the floodwaters flowed in a south and southeast direction to cross the present day Front Range to reach what are today southeast oriented tributary valleys draining to a south oriented flood flow channel on the present day north oriented South Platte River alignment.

Detailed map of Willow Creek-Haystack Creek drainage divide area

Figure 10: Detailed map of Willow Creek-Haystack 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 Willow Creek-Haystack Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. The east-west continental divide serves as the county line and is shown with a labeled line extending from the north edge of figure 10 (near northwest corner) to the east edge of figure 10 (north half). Troublesome Pass is located on the continental divide near the center of figure 10. The south oriented stream flowing from near Troublesome Pass to the south center edge of figure 10 is Haystack Creek, which south of figure 10 flows to southwest oriented East Fork Troublesome Creek. The East Fork Troublesome Creek originates east of Haystack Mountain and flows in a southeast direction to the east edge of figure 10 (near southeast corner) and south and east of figure 10 turns to flow in a southwest and south direction to join south oriented Troublesome Creek. South and west of figure 10 Troublesome Creek flows to the west and southwest oriented Colorado River with water eventually reaching the Pacific Ocean. Willow Creek is the north oriented stream north of Troublesome Pass, which flows to the north center edge of figure 10. North of figure 10 Willow Creek flows to the north-northwest oriented Illinois River with water eventually the Michigan, North Platte, Platte, Missouri, and Mississippi Rivers and the Gulf of Mexico. Troublesome Pass has an elevation of 10,027 feet. Continental divide elevations west of Troublesome Pass and seen in figure 10 rise 11,417 feet and north and west of figure 10 elevations rise to 11,819 feet. Haystack Mountain to the east of Troublesome Pass rises to 11,495 feet and just east of figure 10 continental divide elevations rise to 12,296 feet. Using elevations seen in figure 10 Troublesome Pass is approximately 1400 feet deep. Using more distant elevations Troublesome Pass is almost 1800 feet deep. A second through valley is located near the southeast corner of section 1 and links the valley of a northwest oriented Willow Creek tributary with the southeast oriented East Fork Troublesome Creek headwaters valley. The second through valley or pass has an elevation of between 10,400 and 10,440 feet and is at least 1000 feet deep. These through valleys or passes and other shallower through valleys or passes crossing the continental divide were eroded by diverging and converging south oriented flood flow channels into an erosion surface now preserved, if it is preserved at all, by the highest points seen in figure 10. Headward erosion of a deeper south oriented flood channel on the Troublesome Pass alignment beheaded the diverging southeast oriented flood flow channel leading to the East Fork Troublesome Creek valley. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Willow Creek tributary drainage route. Subsequently Rabbit Ears Range uplift combined with flood flow reversals north of figure 10 ended flood flow across the present day continental divide and created the north oriented Willow Creek drainage route.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.