Abstract:

This essay uses topographic map evidence to interpret landform origins in the Fraser River-Boulder Creek drainage divide area along the east-west continental divide and focuses on the continental divide north of Berthoud Pass and south of Lake Granby. The Colorado River flows in a south direction on the west side of Rocky Mountain National Park and at Lake Granby turns to flow in a southwest direction with water eventually reaching the Pacific Ocean. The Fraser River flows in a north direction toward Lake Granby and turns in a west-northwest direction to join the southwest oriented Colorado River. North-to-south oriented through valleys cross the Colorado River-Fraser River drainage divide area south of Lake Granby. South of the north oriented Fraser River headwaters is Berthoud Pass, which crosses a west-to-east oriented continental divide segment and which links the north oriented Fraser River valley with the east oriented Clear Creek valley. East of the north oriented Fraser River is a high north-to-south oriented mountain ridge, which also forms the east-west continental divide. East of the continental divide are headwaters of east oriented Boulder Creek tributaries, which join near or east the Colorado Front Range east flank to form northeast oriented Boulder Creek, which flows to northeast oriented St Vrain Creek, which in turn flows to the South Platte River. North-to-south oriented through valleys cross drainage divides between the east oriented Boulder Creek tributaries and also between east oriented South Boulder Creek and east oriented Clear Creek to the south. Valley orientations, through valleys and passes, barbed tributaries, the continental divide orientation, and similar evidence seen on topographic maps is illustrated and interpreted in the context of immense melt water floods from the western margin of thick North American ice sheet. Floodwaters flowed from western Canada to and across Colorado at a time when Colorado mountain ranges were beginning to emerge. Mountain ranges emerged as floodwaters flowed across them, as ice sheet related crustal warping raised the mountain masses and the entire region, and as deep valleys eroded headward into the region from both the east and the west. Initially floodwaters moved in south directions until headward erosion of the deep southwest oriented Colorado River valley captured a major complex of diverging and converging south oriented flood flow channels that had previously been captured (further to the south) by headward erosion of the east oriented Clear Creek valley. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented Fraser River drainage route and its north oriented tributary drainage routes. The deep north-to-south oriented flood flow channels on the present day Fraser River alignment ended flood flow across the present day north-to-south continental divide to the east oriented Boulder Creek tributary valleys.

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 Fraser River-Boulder Creek drainage divide area landform origins along the east-west continental divide. 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 Fraser River-Boulder Creek drainage divide area landform evidence along the east-west continental divide will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Fraser River-Boulder Creek drainage divide area location map

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

Figure 1 provides a location map for the Fraser River-Boulder Creek drainage divide area along the east-west continental divide and illustrates a region in north central Colorado. The Colorado Front Range is located west of the cities of Denver, Boulder. Longmont, and Fort Collins and the region east of the Front Range is the Colorado Piedmont. The South Platte River flows in a north direction from the south edge of figure 1 to Denver and then almost to Greeley where it turns to flow in a northeast and then southeast direction to the east edge of figure 1 (north of center). East of figure 1 the South Platte River turns to flow in a northeast direction to reach western Nebraska and to join the Nebraska Platte River. Rocky Mountain National Park is shown and labeled in figure 1. The Colorado River originates near the northwest corner of Rocky Mountain National Park and flows in a south direction to Lake Granby near the southwest corner of the Park and then turns to flow in a west-southwest and southwest direction to the west edge of figure 1 (south half-near Bond). The Fraser River is not shown in figure 1, but originates near Berthoud Pass and flows in a north and northwest direction through the towns of Winter Park, Fraser, and Tabernash to join the Colorado River near Granby. The Big Thompson River originates in Rocky Mountain National Park and flows in a southeast, northeast, and east-southeast direction to join the northeast and southeast oriented South Platte River. The unlabeled east oriented streams south of the Big Thompson River and converging near Longmont are tributaries to St Vrain Creek, which flows in a southeast direction from Lyons to Longmont and then in a northeast direction to join the northeast and southeast oriented South Platte River. Boulder Creek is the east and northeast oriented tributary flowing through the city of Boulder and joining St Vrain Creek east of Longmont. Clear Creek is an unlabeled east oriented South Platte River tributary flowing from south of Berthoud Pass to Golden and then to the South Platte River. The Fraser River-Boulder Creek drainage divide area along the east-west continental divide investigated in this essay is located east of the north and northwest oriented Fraser River and focuses on the region close to the continental divide.

While difficult to visualize based on modern-day topography Colorado drainage routes developed during immense melt water floods from a thick North American ice sheet at a time when Colorado mountain ranges were beginning to emerge. Floodwaters flowed from western Canada to and across Colorado as the mountain ranges emerged. Colorado mountain ranges emerged as floodwaters flowed across them, as ice sheet related crustal warping raised the mountain masses and most of Colorado, and as deep valleys eroded headward into Colorado from the Pacific Ocean in the west and from the Gulf of Mexico in the east. Initially floodwaters flowed in south directions, but flood flow directions changed and even reversed as crustal warping raised the mountains and the entire region and as headward erosion of deep valleys captured the immense south oriented flood flow. East oriented valleys eroded headward in sequence into the emerging Front Range from south to north from south oriented flood flow channels on the Colorado Piedmont to capture south oriented flood flow moving across the east side of the emerging mountains. At about the same time the deep southwest oriented Colorado River valley eroded headward to capture south oriented flood flow channels on the west side of the emerging Colorado Front Range. Headward erosion of deep southwest oriented Colorado River valley captured major south oriented flood flow channels flowing on the alignment of the present day north oriented Cache la Poudre River headwaters, south oriented Colorado River in Rocky Mountain National Park, and north and northwest oriented Fraser River to reach the Berthoud Pass location and then the newly eroded east oriented Clear Creek valley. Floodwaters on the north and northwest ends of the beheaded south oriented flood flow channels reversed flow direction to create the north and northwest oriented Fraser River and tributary drainage routes. Further to the east headward erosion of the deep southeast and northeast oriented South Platte River valley from western Nebraska captured the south oriented flood flow channels on the Colorado Piedmont. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to flow to the deeper South Platte River valley and to create the north oriented South Platte River and tributary drainage routes seen on the Colorado Piedmont today. Headward erosion of the east and southeast oriented Cache la Poudre River valley beheaded the south oriented flood flow channel on the west side of Rocky Mountain National Park. Floodwaters on the north end(s) of the beheaded flood flow channel(s) reversed flow direction to create the north oriented Cache la Poudre River headwaters drainage route(s). These flood flow captures and reversals were taking place as crustal warping was raising the mountains and the entire region.

Detailed location map for Fraser River-Boulder Creek drainage divide area

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

Figure 2 provides a detailed location map for the Fraser River-Boulder Creek drainage divide area along the east-west continental divide. The east-west continental divide is shown with a dashed line extending from the north center edge of figure 2 to the south edge of figure 2 (west half). Green colored areas are National Forest lands located in Colorado mountain ranges. The red-brown area straddling the north center edge of figure 2 is the southern margin of Rocky Mountain National Park. The Colorado River flows in a south direction to Lake Granby at the southwest corner of Rocky Mountain National Park and then turns in a southwest direction to flow to the west edge of figure 2 (north half-near Hot Sulphur Springs). Arapaho Creek is a northwest oriented Colorado River tributary flowing from the continental divide to Lake Granby. Berthoud Pass is located on the continental divide near the south edge of figure 2. The Fraser River originates near Berthoud Pass and flows in a north, north-northwest, and northwest direction through the towns of Winter Park, Fraser, and Tabernash to join the Colorado River near the town of Granby. Strawberry Creek is a west oriented stream flowing to the Fraser River near Granby. Meadow Creek is a northwest, west, and south-southwest oriented stream joining the Fraser River near Tabernash. Ranch Creek is a northwest and north-northwest oriented tributary also joining the Fraser River near Tabernash. The east oriented stream south of Berthoud Pass is the West Fork Clear Creek with Clear Creek flowing in an east direction to the east edge of figure 2 at Golden. East of figure 2 Clear Creek flows to the north oriented South Platte River. Boulder Creek tributary headwaters are located on the east side of the continental divide in the center region of figure 2 and flow in an east and east-northeast direction to the city of City of Boulder and then to the east edge of figure 2 (north of center). East of figure 2 Boulder Creek flows in a northeast direction to join northeast oriented St Vrain Creek, which then flows to the northeast, southeast, and northeast oriented South Platte River. North Boulder Creek originates east of the Arapaho Creek headwaters and flows in an east, southeast, and east-northeast direction to join Boulder Creek west of Boulder. South Boulder Creek originates in western Gilpin County on the south side of Moffat Tunnel and flows in a northeast, east-northeast, east, and north direction to join Boulder Creek on the east side of Boulder (near east edge of figure 2). Before leaving figure 2 note the north and northwest oriented streams, including the Fraser River, flowing to the south and southwest oriented Colorado River as barbed tributaries and how Meadow Creek flows in a south direction to join the north oriented Fraser River as a barbed tributary. The north and northwest barbed tributaries provide evidence of flow reversals on what at one time were south oriented flood flow channels which were beheaded by headward erosion of the deeper southwest oriented Colorado River valley. The south oriented Meadow Creek segment is a relic of the original south oriented flood flow direction before the reversal of flood flow on the Fraser River alignment.

Colorado River-Fraser River drainage divide area

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

Figure 3 provides a topographic map of Colorado River-Fraser River drainage divide area. The map contour interval for figure 3 is 50 meters. The Colorado River flows in a west-southwest direction across the northwest corner of figure 3. North of figure 3 the Colorado River is oriented in a south direction. The Fraser River flows in a north-northwest, north, and west-northwest direction from south center edge of figure 3 to join the Colorado River near the west edge of figure 3. Except for the west-northwest segment near the Colorado River the Fraser River is flowing to the Colorado River as a barbed tributary. Lonesome Peak is a labeled high point south of Monarch Lake in the northeast quadrant of figure 3. Strawberry Creek originates between Lonesome Peak and Meadow Creek Reservoir and flows in a northwest, west, north, southwest, northwest, and southwest direction to join the Fraser River. Meadow Creek originates at Columbine Reservoir (near east edge of figure 3-south half) and flows in a northwest direction to Meadow Creek Reservoir and then in west-southwest and south direction to join the north-northwest oriented Fraser River as a barbed tributary near the south center edge of figure 3. Arapaho Creek flows in a northwest direction from the east center edge of figure 3 to the north edge of figure 3 (east half) and north of figure 3 joins the south and southwest oriented Colorado River at Lake Granby as a barbed tributary. Walden Hollow is located just west of the north center edge of figure 3 and is drained in a north-northwest direction by a barbed tributary to the south and southwest oriented Colorado River. A through valley in section 21 links north-northwest oriented Walden Hollow with the Strawberry Creek valley. A north-to-south through valley links a north oriented tributary to a north oriented Strawberry Creek segment with the south oriented Meadow Creek segment and multiple north-to-south oriented through valleys cross drainage divides in the central region of figure 3. These north-to-south oriented through valleys were eroded by south oriented flood flow moving from a south oriented flood flow channel on the Colorado River alignment (north of figure 3) to a south oriented flood flow channel on the present day north oriented Fraser River alignment (south of figure 3). These diverging and converging flood flow channels were beheaded by headward erosion of the much deeper southwest oriented Colorado River valley and the west-northwest oriented Fraser River and west oriented Strawberry Creek valley, which captured the south oriented flood flow channels in sequence from west to east. The west oriented Strawberry Creek valley eroded headward along south oriented flood flow channel and then beheaded and reversed a flood flow channel to the east and eroded headward along the reversed flood flow before turning to erode headward along another south oriented flood flow channel to create its S-shaped drainage route. Headward erosion of the deeper southwest oriented Colorado River valley then beheaded and reversed the flood flow channel in Walden Hollow and subsequently beheaded and reversed the south oriented flood flow channel on the Arapaho Creek alignment to create those north-northwest oriented drainage routes.

Detailed map of Strawberry Creek-Meadow Creek drainage divide area

Figure 4: Detailed map of Strawberry Creek-Meadow 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 Strawberry Creek-Meadow Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 40 feet. The Fraser River flows in a north direction from near the southwest corner of figure 4 to the west edge of figure 4 (north of center) and west of figure 4 turns to flow in a west-northwest direction to join the southwest oriented Colorado River. Meadow Creek flows in a west-southwest and south direction near the southeast corner of figure 4 and south of figure 4 joins the north oriented Fraser River as a barbed tributary. Strawberry Creek flows in a west, north-northwest, southwest, north-northwest, and southwest direction from the east edge of figure 4 (north of center) to join the Fraser River near the west edge of figure 4. Behler Creek flows in a south, southwest, northwest, west, and northwest direction in the southwest quadrant of figure 4 and joins the north oriented Fraser River. A small lake can be seen in the northwest quadrant of section 31 near the north edge of figure 4. The small lake is at the south end of Walden Hollow, which north of figure 4 drains in a north-northwest direction to the south and southwest oriented Colorado River as a barbed tributary. North-to-south oriented through valleys in sections 16 and 17 link a north oriented Strawberry Creek tributary valley with the south oriented Meadow Creek valley. The westernmost through valley in section 17 has a floor elevation of 9305 feet. Elevations in section 8 to the northwest rise to 9891 feet and elevations in section 10 to the east exceed 10,400 feet suggesting the through valley is approximately 600 feet deep. Through valleys in sections 16 and 17 are obviously diverging and converging suggesting they were eroded by south oriented flood flow channels. A north-to-south oriented through valley in the southwest corner of section 31 links the north oriented Walden Hollow drainage route with the Strawberry Creek valley and then continues in a south direction across the Strawberry Creek-Behler Creek drainage divide and then the drainage divide to the south of Behler Creek. South oriented flood flow channels eroded this through valley prior to headward erosion of the deep southwest oriented Colorado River valley (north of figure 4). Headward erosion of the west oriented Behler Creek valley first captured the south oriented flood flow and next headward erosion of the Strawberry Creek valley captured the south oriented flood flow. Subsequently headward erosion of the southwest oriented Colorado River valley beheaded and reversed the flood flow channel to create the north-northwest oriented Walden Hollow drainage route. Reversed flood flow on the Walden Hollow drainage route captured south oriented flood flow still moving west of the actively eroding Colorado River valley head. The south oriented flood flow moved in a southwest direction on the Little Strawberry Creek drainage route to section 32 and then turned to flow in a northwest direction across section 31 to reach the north-northwest oriented Walden Hollow drainage route. The deep through valley in the southeast quadrant of section 31 provides evidence of the capture of the south oriented flood flow by reversed flood flow in Walden Hollow.

Arapaho Creek-North Fork Middle Boulder Creek drainage divide area

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

Figure 5 illustrates the Arapaho Creek-North Fork Middle Boulder Creek drainage divide area east and slightly south 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 northeast corner) to the south edge of figure 5 (east half). North Fork Middle Boulder Creek flows in a northeast and then southeast direction from near the continental divide to the southeast corner of figure 5. East and south of figure 5 North Fork Middle Boulder Creek flows to east-northeast Middle Boulder Creek, which then joins other Boulder Creek tributaries to form east-northeast and northeast oriented Boulder Creek, which flows to northeast oriented St Vrain Creek, which flows to the South Platte River with water eventually reaching the Gulf of Mexico. North Boulder Creek originates in the Green Lakes area north of Mount Albion and South St Vrain Creek is the stream originating near the continental divide just to the north of North Boulder Creek. The Fraser River flows in a north-northwest direction from the south edge of figure 5 (west half) to the west edge of figure 5 (north half) and west of figure 5 turns to flow in a west-northwest direction to join the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. Meadow Creek, Strawberry Creek, and Behler Creek can be seen as Fraser River tributaries. Arapaho Creek originates just north of the North Fork Middle Boulder Creek headwaters (although on the northwest side of the continental divide) and flows in a north-northwest direction to the north center edge of figure 5. North of figure 5 Arapaho Creek flows to the south and southwest oriented Colorado River at Lake Granby. The Arapaho Creek alignment is almost identical with the North Fork Middle Boulder Creek alignment suggesting the alignment was once used by a southeast oriented flood flow channel. Arapaho Pass links the two valleys and does not show up well in figure 5. On a more detailed map the Arapaho Pass floor elevation is 11,908 feet while adjacent mountains rise to more than 12,800 feet. When southeast oriented floodwaters eroded Arapaho Pass the high mountain ridge did not exist nor did the deep Arapaho Creek valley exist. Southeast oriented flood flow on the Arapaho Creek alignment was probably beheaded by headward erosion of deeper south-oriented flood flow channels converging on the Fraser River alignment to flow in a south direction across Berthoud Pass (south of figure 5 and which is approximately 600 feet lower than Arapaho Pass). The deeper south-oriented flood flow channels were then beheaded and reversed by headward erosion of the much deeper southwest oriented Colorado River valley to create the north oriented Fraser River drainage route. What is important to remember is south oriented flood flow channels beheaded and reversed flood flow channels crossing the present day east-west continental divide and then lowered the region west of the continental divide. A similar process took place east of the continental divide with the result that today the continental divide seen in figure 5 is a high mountain ridge and is not crossed by deep passes.

Middle Boulder Creek-South Boulder Creek drainage divide area

Figure 6: Middle Boulder Creek-South Boulder Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 provides a topographic map of the Middle Boulder Creek-South Boulder Creek drainage divide area south and east of figure 5 and includes an overlap area with figure 5. The map contour interval for figure 6 is 50 meters. The east-west continental divide is shown with a labeled dashed line extending from the north edge of figure 6 (west of center) along the crest of the high mountain ridge to the south edge of figure 6 (west half). The north-northwest oriented Fraser River can just barely be seen in the southwest corner of figure 6. The west end of Moffat Tunnel is located at the southwest corner of figure 6 with the east end at East Portal in the South Boulder Creek valley. South Boulder Creek flows in an east direction from East Portal to the east edge of figure 6 (south half). East of figure 6 South Boulder Creek flows in an east direction (with many twists and turns) to the mountain front and then turns to flow in a north direction to join northeast oriented Boulder Creek. North Fork Middle Boulder Creek originates on the southeast side of the continental divide near the north edge of figure 6 and flows in a northeast and southeast direction to join the east-south South Fork Middle Boulder Creek near the center of figure 6 and then to flow as Middle Boulder Creek in an east and east-northeast direction to the east edge of figure 6 (slightly north of center). East of figure 6 Middle Boulder Creek joins North Boulder Creek and South Boulder Creek to form northeast oriented Boulder Creek, which joins northeast oriented St Vrain Creek. North Boulder Creek flows in a southeast and east direction from the north edge of figure 6 (east half) to the east edge of figure 6 (north half) and east of figure 6 joins Middle Boulder Creek. While not as obvious as on the west side of the continental divide north-to-south through valleys link at least some of the east oriented Boulder Creek tributary valleys. Tolland is a siding name on the railroad east of East Portal. Jenny Creek flows in an east and south direction to join east oriented South Boulder Creek near Tolland. The south oriented Jenny Creek segment is on approximately the same alignment as the southeast oriented North Fork Middle Boulder Creek alignment suggesting flood flow on the North Fork Middle Boulder Creek flowed in a south direction prior to headward erosion of deep east oriented South Fork Boulder Creek valley and subsequently the deep Middle Boulder Creek valley. North and east of the Jenny Creek elbow of capture (where Jenny Creek turns in a south direction) a through valley links the Jenny Creek valley with the Middle Boulder Creek valley. The through valley is defined by three contour lines on the southeast side, which suggests the through valley is more than 100 meters deep.  The through valley was probably eroded by a diverging flood flow channel moving to what at that time was the actively eroding Middle Boulder Creek valley. If so flood flow was still moving across the continental divide at the time the east oriented South Boulder Creek and Middle Creek valleys eroded headward into the region. Headward  erosion of south oriented flood flow channels on the present day north oriented Fraser River alignment on the west side of the continental divide ended flood to the headwaters areas of South and Middle Boulder Creeks.

South Boulder Creek-North Clear Creek drainage divide area

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

Figure 7 illustrates the South Boulder Creek-North Clear Creek drainage divide area south and slightly west of figure 6 and includes an overlap area with figure 6. The map contour interval for figure 7 is 50 meters. Berthoud Pass is located near the southwest corner of figure 7. The east-west continental divide is shown with a labeled dashed line extending from Berthoud Pass along the high mountain ridge to the north edge of figure 7 (west of center). The Fraser River originates near Berthoud Pass and flows in a north and north-northwest direction to near the northwest corner of figure 7. Fraser River tributaries originating near the continental divide flow in northwest directions to reach the Fraser River. Rogers Pass crosses the continental divide near the center of figure 7. South Boulder Creek originates east of Rogers Pass and flows in a northeast and east direction to the east edge of figure 7 (north half). East of figure 7 South Boulder Creek flows in an east and north direction to join northeast oriented Boulder Creek. James Peak is located south of Rogers Pass and Mammoth Gulch originates on the east side of James Peak and drains in a northeast and north direction to South Boulder Creek. Fall River Reservoir is located south of James Peak. The Fall River originates near Fall River Reservoir and flows in a southeast direction to the south center edge of figure 7. South of figure 7 the Fall River flows to east oriented Clear Creek. North Clear Creek is located in the southeast quadrant of figure 7 and flows in a southeast direction to the east edge of figure 7 (south half). East of figure 7 North Clear Creek flows to east oriented Clear Creek. Pine Creek is a south oriented North Clear Creek tributary originating near the town of Apex. North of the Pine Creek headwaters is north oriented Jenny Lind Gulch, which drains to east oriented South Boulder Creek. Through valleys crossing the South Boulder Creek-Clear Creek drainage are easy to see in figure 7. West of Pine Creek is Montana Mountain and west of Montana Mountain is Kingston Peak. Between Montana Mountain and Kingston Peak the Mammoth Creek-North Clear Creek drainage divide elevations decreases by approximately 100 meters providing evidence of south and southeast oriented flood flow channels beheaded by headward erosion of the deeper northeast oriented Mammoth Creek valley. A deeper north-to-south oriented through valley links the north oriented Jenny Lind Gulch valley with the south oriented Pine Creek valley. Elevations on the through valley floor are between 3100 and 3150 meters. Elevations on Montana Mountain to the west rise to more than 3300 meters as do elevations on Oregon Hill to the east suggesting the through valley is at least 150 meters deep. Missouri Creek is a south oriented North Clear Creek tributary near the east edge of figure 7. A still deeper north-to-south oriented through valley near Wideawake links the south oriented Missouri Creek valley with north oriented South Boulder Creek tributary valleys. These through valleys were eroded by south oriented flood flow moving on the east side of the continental divide at the same time south oriented flood flow was moving along the present day north oriented Fraser River alignment on the west side of the continental divide and then through Berthoud Pass to reach the east oriented West Fork Clear Creek valley. The ridge or divide between south oriented flood flow channels became the east-west continental divide when headward erosion of the deep southwest oriented Colorado River valley beheaded and reversed flood flow channels on Fraser River alignment.

Detailed map of Jenny Lind Gulch-Pine Creek drainage divide area

Figure 8: Detailed map of Jenny Lind Gulch-Pine 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 Jenny Lind Gulch-Pine Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. South Boulder Creek flows in an east direction from near the northwest corner of figure 8 to the north edge of figure 8 (east of center). East of figure 8 South Boulder Creek flows in an east direction to the east flank of the mountains and then turns to flow in a north direction to join northeast oriented Boulder Creek. Mammoth Creek flows in a northeast and north-northeast direction from the west edge of figure 8 (south half) to join South Boulder Creek. Jenny Lind Gulch is a north oriented drainage route in the northeast quadrant of figure 8 and north of figure 8 joins South Boulder Creek. North Clear Creek originates near the southwest corner of figure 8 and flows in an east and southeast direction to the south edge of figure 8 (slightly west of center). South of figure 8 North Clear Creek flows in a southeast direction to join east oriented Clear Creek. Pine Creek originates south of the Jenny Lind Gulch headwaters and flows in a south direction to the south edge of figure 8 (east half). South of figure 8 Pine Creek flows to southeast oriented North Clear Creek. A north-to-south oriented through valley or pass links the north oriented Jenny Lind Gulch valley with the south oriented Pine Creek valley. The through valley or pass elevation at the drainage divide is 10,215 feet. Colorado Mountain to the west rises to 10,870 feet and Dakota Hill to the east rises to 10,929 feet suggesting the through valley or pass is approximately 650 feet. The through valley or pass was eroded by south oriented flood flow prior to headward erosion of the deeper east oriented South Boulder Creek valley. The south oriented flood flow was probably moving to what at that time was the newly eroded southeast oriented North Clear Creek valley, which had eroded headward from the newly eroded east oriented Clear Creek valley. Headward erosion of the east oriented South Boulder Creek valley beheaded and reversed the south oriented flood flow channel to create the north oriented Jenny Lind Gulch drainage route. Shallower through valleys can be seen in the southwest quadrant of figure 8 linking the northeast oriented Mammoth Creek valley with south and southeast oriented North Clear Creek headwaters valleys. These through valleys were eroded by south and/or southeast oriented flood flow channels prior to headward erosion of the deeper northeast and north-northeast oriented Mammoth Creek valley from what was at that time the actively eroding east oriented South Boulder Creek valley.

Fraser River-West Fork Clear Creek drainage divide area

Figure 9: Fraser River-West Fork Clear Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Fraser River-West Fork Clear Creek drainage divide area south and west of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 50 meters. The east-west continental divide is shown with a dashed line extending in a south and southwest direction along the crest of the high mountain ridge from the north center edge of figure 9 to Berthoud Pass in the southwest quadrant of figure 9. From Berthoud Pass the continental divide extends in a west direction to Vasquez Pass and then to the west edge of figure 9. North and west of the continental divide drainage is to the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. South and east of the continental divide drainage flows to the north oriented South Platte River, with water eventually reaching the Gulf of Mexico. The Fraser River originates north of Berthoud Pass and flows in a north direction to the north edge of figure 9 (west of center). North of figure 9 the Fraser River turns in a west-northwest direction to join the southwest oriented Colorado River. Vasquez Creek flows in a north direction from Vasquez Pass to the north edge of figure 9 and joins the Fraser River north of figure 9. The West Fork Clear Creek flows from near the southwest corner of figure 9 to join northeast oriented Clear Creek east of the town of Empire. Clear Creek then flows in an east direction to the east edge of figure 9 and east of figure 9 Clear Creek flows to the north oriented South Platte River. The north oriented Fraser River alignment is on approximately the same alignment as the south oriented Colorado River headwaters in Rocky Mountain National Park, which are linked by deep passes with north oriented Cache la Poudre River headwaters drainage routes. Prior to headward erosion of the southwest oriented Colorado River valley diverging and converging south oriented flood flow channels developed on this north-to-south oriented alignment with the south oriented floodwaters flowing through the Berthoud Pass and Vasquez Pass valleys to reach what at that time was the newly eroded West Fork Clear Creek valley. Headward erosion of the deep southwest oriented Colorado River valley north of figure 9 captured the south oriented flood flow channels and diverted the floodwaters in a southwest direction. Floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented Fraser River drainage route and its north oriented Vasquez Creek tributary drainage route and to create the east-west continental divide. Note how the continental divide is oriented in an west-to-east direction where the south oriented floodwaters once crossed it and is oriented in a north-to-south direction where it was a divide between south oriented flood flow channels on either side.

Detailed map of Fraser River-West Fork Clear Creek drainage divide area

Figure 10: Detailed map of Fraser River-West Fork Clear 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 Fraser River-West Fork Clear 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 is shown with a labeled dashed line extending from the west center edge of figure 10 to the east center edge of figure 10. South of the continental divide drainage is to the north oriented South Platte River while north of the continental divide drainage is to the southwest oriented Colorado River. West Fork Clear Creek flows in an east direction near the south edge of figure 10 and east of figure 10 joins the north oriented South Platte River. Berthoud Pass crosses the continental divide in the east half of figure 10. The Fraser River originates north of Berthoud Pass and flows in a north-northeast direction to the north edge of figure 10. North of figure 10 the Fraser River flows in a north, north-northwest, and west-northwest direction to join the southwest oriented Colorado River. Vasquez Creek flows in a northeast and north direction across the northwest corner of figure 10 and north of figure 10 joins the Fraser River. Vasquez Pass crosses the continental divide in the southwest quadrant of figure 10. A north oriented tributary flows from near Vasquez Pass to join north oriented Vasquez Creek. Berthoud Pass has an elevation of 11,315 feet and Vasquez Pass has an elevation of between 11,720 and 11,760 feet. Colorado Mines Peak to the east of Berthoud Pass rises to 12,493 and Mt Flora just east of figure 10 rises to 13,137 feet. Vasquez Peak west of Vasquez Pass rises to 12,947 feet. Stanley Mountain between the two passes rises 12,521 feet. Depending on which elevations are used Berthoud Pass could be considered to be about 1200 feet deep or as much as 1700 feet deep and Vasquez Pass could be about 800 feet deep or almost 1200 feet deep. Whatever their depths Berthoud Pass and Vasquez Pass are water-eroded valleys and were eroded by south oriented flood flow channels leading to what at that time was the newly eroded and deep east oriented West Fork Clear Creek valley. The north oriented Fraser River and Vasquez Creek alignments are approximately the same as the alignments of the south oriented Colorado River on the west side of Rocky Mountain National Park and the north oriented Cache la Poudre River headwaters north of the Colorado River headwaters (see figure 1). Prior to headward erosion of the much deeper Colorado River valley south oriented floodwaters flowed in diverging and converging flood flow channels from Wyoming across the emerging Colorado mountains to the Berthold Pass and Vasquez Pass valleys to reach the east oriented West Fork Clear Creek valley with floodwaters then flowing to south oriented flood flow channels on the present day north oriented South Platte River alignment. Headward erosion of the deep southwest oriented Colorado River valley beheaded and reversed the south oriented flood flow channels to create the north oriented Vasquez Creek and Fraser River drainage routes, Vasquez and Berthoud Passes, and the east-west continental divide.

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.