Rock Creek- Clarks Fork Yellowstone River drainage divide area landform origins in the Beartooth Mountains, Montana and Wyoming, USA

Authors


Abstract:

This essay uses topographic map evidence to interpret landform origins located in the Beartooth Mountains along the Montana-Wyoming state line east of Yellowstone National Park and between north oriented Rock Creek headwaters and tributaries and the southeast and north-northeast oriented Clarks Fork of the Yellowstone River drainage basin . Rock Creek originates in the high Beartooth Mountains and flows in an east, northeast, and north-northeast direction to join the north-northeast oriented Clarks Fork of the Yellowstone River near Silesia, Montana, which then flows in a northeast direction to join the northeast Yellowstone River near Laurel, Montana. The Clarks Fork of the Yellowstone River also originates in the high Beartooth Mountains, west of the Rock Creek headwaters, with the Clarks Fork first flowing in a southeast direction into Wyoming before turning to flow in a northeast and north-northeast direction back into Montana. Multiple through valleys have been eroded across high Beartooth Mountain ridges and cross drainage divides between deep Rock Creek tributary valleys and also drainage divides between the Rock Creek and the Clarks Fork of the Yellowstone River. The through valleys are interpreted to have been eroded by multiple south and southeast oriented flood flow channels prior to emergence of the Beartooth Mountains as a high mountain range. Floodwaters are interpreted to have been derived from a rapidly melting thick North American ice sheet located in a deep “hole” and were flowing in south and southeast directions from the ice sheet’s western margin in western Canada across Montana and into Wyoming. At that time the Beartooth Mountains and other mountain ranges did not stand high above surrounding regions and floodwaters were free to move across the region, although crustal warping caused by the ice sheet’s great weight was raising the mountain ranges as floodwaters flowed across the region. Headward erosion of the deep northeast oriented Yellowstone River valley and northeast and north-northeast Clarks Fork of the Yellowstone River valley first captured the massive southeast and south oriented flood flow and diverted the flow into space in the deep “hole” being opened up as the ice sheet melted. Beartooth Mountains uplift combined with headward erosion of the deep east and northeast oriented Rock Creek valley next captured the south and southeast flood flow and diverted the floodwaters more directly to the northeast oriented Clarks Fork and Yellowstone River valley. Beartooth Mountains uplift continued after flood flow across the region ended and at a later time valley glaciers further modified the Beartooth Mountains 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 Rock Creek-Clarks Fork of the Yellowstone River drainage divide area landform origins in the Beartooth Mountains along the Montana and Wyoming border, USA. 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 Rock Creek-Clarks Fork of the Yellowstone River drainage divide area landform evidence in the Beartooth Mountains along the Montana-Wyoming border will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Rock Creek-Clarks Fork of the Yellowstone River drainage divide area location map

Figure 1: Rock Creek-Clarks Fork of the Yellowstone 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 Rock Creek-Clarks Fork of the Yellowstone River drainage divide area in the Beartooth Mountains east of Yellowstone National Park and illustrates a region of south-central Montana in the north half and northwest Wyoming in the figure 1 south half. Yellowstone National Park is the yellow shaded area in the southwest corner of figure 1 (west half). The Beartooth Mountains are not labeled in figure 1, but extend eastward from the northeast corner of Yellowstone National Park along the Montana-Wyoming border to near Red Lodge, Montana. The Yellowstone River flows from the Yellowstone National Park area in a northwest direction and once in Montana turns to flow in a northeast direction to the north edge of figure 1 before turning to flow in an east-southeast direction to Columbus where it then turns to flow in a northeast direction to Billings and the figure 1 north edge (near northeast corner). The Clarks Fork of the Yellowstone River originates north of Cooke City, Montana and flows in a southeast direction into Wyoming before turning to flow in a northeast and north-northeast direction around the east end of the Beartooth Mountains to join the Yellowstone River near Laurel, Montana. Rock Creek is the unlabeled east and north-northeast oriented stream originating near Silver Run Peak and flowing to Red Lodge, Roberts, Boyd, and Joliet, Montana before joining the Clarks Fork of the Yellowstone River near Silesia. The Rock Creek-Clarks Fork of the Yellowstone River drainage divide area in the Beartooth Mountains illustrated and discussed here begins north of Red Lodge and extends south and west along the Montana-Wyoming state line to the Rock Creek headwaters region (south of Silver Run Peak).

Looking at the big picture erosion history the figure 1 drainage routes developed as immense south and southeast oriented melt water floods flowed across the region and crustal warping raised the Beartooth Mountains at approximately the same time as the deep Yellowstone River valley eroded headward from a deep “hole” in which a large North American ice sheet was rapidly melting. The deep “hole” was located north and east of the figure 1 map area, which is located along the deep “hole’s” deeply eroded southwest wall. The east and northeast oriented Yellowstone River valley and its northeast oriented tributary valleys eroded headward from the deep “hole” to capture immense south and southeast oriented ice marginal floods flowing from western Canada across Montana. At that time mountain ranges in the figure 1 map area, including Beartooth Mountains, did not stand high above the surrounding regions and floodwaters could freely flow across the entire figure 1 map area. Ice sheet related crustal warping raised the Beartooth Mountains as the immense melt water floods flowed across the region and contributed to deep erosion of the Beartooth Mountains upland area and to formation of the present day Rock Creek-Clarks Fork of the Yellowstone River drainage divide. As the Beartooth Mountains were uplifted floodwaters flowing across the region began to carve deep valleys or flood flow channels into the rising mountain mass, eroding headward from south oriented flood flow channels in the Bighorn Basin. The southeast oriented Clarks Fork of the Yellowstone River segment is located in one such deep valley, which was being carved headward into the rising mountain mass. Headward erosion of the deep northeast and north-northeast oriented Clarks Fork of the Yellowstone River valley segment later captured the deep southeast oriented flood flow channel and diverted the flood water to the newly eroded and deeper northeast oriented Yellowstone River valley (which was eroding headward from space in the deep “hole” the melting ice sheet had occupied). Headward erosion of the deep northeast oriented Rock Creek valley and its tributary valleys from the actively eroding northeast oriented Clarks Fork of the Yellowstone River valley next captured the south and southeast oriented flood flow which had been moving to the actively eroding southeast oriented Clarks Fork of the Yellowstone River valley segment. Headward erosion of the east oriented Yellowstone River valley (upstream from Laurel, Montana) combined with continued Beartooth Mountains uplift later beheaded and reversed south and southeast oriented flood flow routes to the newly eroded Rock Creek valley and tributary valleys.

Detailed location map for Rock Creek-Clarks Fork of the Yellowstone River drainage divide area

Figure 2: Detailed location map Rock Creek-Clarks Fork of the  Yellowstone 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 Rock Creek-Clarks Fork of the Yellowstone River drainage divide area in the Beartooth Mountains east of Yellowstone National Park. The brown shaded area in the southwest quadrant of figure 2 represents areas in Yellowstone National Park. The west to east oriented dashed line running through the northern margin of the Yellowstone National Park area is the Montana-Wyoming state line. Green shaded areas are National Forest lands, which are generally located in mountainous regions. The green shaded area north of Yellowstone National Park is located in the Absaroka Range while the green shaded areas east and northeast of Yellowstone National Park are located in the Beartooth Mountains. The Clarks Fork of the Yellowstone River originates a short distance north of Cooke City, Montana (near northeast corner of Yellowstone National Park) and flows in a southeast direction almost to the south center edge of figure 2. From near the south center edge of figure 2 the Clarks Fork of the Yellowstone River flows in a northeast and north-northeast direction to the northeast corner of figure 2. East oriented tributaries to the northeast and north-northeast oriented Clarks Fork of the Yellowstone River segment include Bear Creek (near Red Lodge), Line Creek (just south of the state line), and Littlerock Creek (south of Line Creek). Note locations of the Beartooth Plateau and the Line Creek Plateau just north of the state line. Rock Creek originates just east of the words “Beartooth Plateau” (near center of figure 2) and flows in a southeast direction to the state line and then turns to flow in an east and northeast direction to Red Lodge, Montana. From Red Lodge Rock Creek flows in a north-northeast direction and joins the Clarks Fork of the Yellowstone River north and east of figure 2. West Fork Rock Creek and Lake Fork Rock Creek are major east oriented Rock Creek tributaries located in the Beartooth Mountains.

Rock Creek-Clarks Fork of the Yellowstone River drainage divide area north of Red Lodge, Montana

Figure 3: Rock Creek-Clarks Fork of the Yellowstone River drainage divide area north of Red Lodge, Montana. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the Rock Creek-Clarks Fork of the Yellowstone River drainage divide area north of Red Lodge, Montana. Red Lodge is located at the southwest corner of figure 3. Rock Creek flows in a north-northeast direction from Red Lodge to the north edge of figure 3 and is located between East Bench and West Bench. Note how Clear Creek and its tributaries Knowlton Creek and Rosetta Creek originate on East Bench and then flow parallel to Rock Creek with Clear Creek joining Rock Creek north of figure 3. While not seen completely in figure 3 north oriented streams on West Bench include Red Lodge Creek, which after flowing in a north direction west of West Bench turns to flow in a northeast and east direction to join Rock Creek. These streams flowing in what appear to be diverging and converging channels suggests the presence of a former anastomosing channel complex formed by massive north-northeast oriented flood flow moving across the entire Rock Creek drainage basin as seen in figure 3. What makes that observation particularly intriguing is the Rock Creek drainage basin in figure 3 is at a much higher elevation than the Clarks Fork of the Yellowstone River drainage basin seen just to the east. The Clarks Fork of the Yellowstone River flows in a north-northeast direction in the southeast corner of figure 3. The map contour interval for figure 3 is 50 meters and the Clarks Fork channel elevation is less than 1150 meters while Rock Creek near the north edge of figure 3 crosses the 1500-meter contour line and just south of Red Lodge crosses the 1750-meter contour line. In other words the Clarks Fork valley is roughly 300-400 meters deeper than the Rock Creek drainage basin, which appears to have been eroded by massive north-northeast oriented floods. The best explanation for this situation is the Clarks Fork valley was also eroded by immense north-northeast oriented floods, probably at about the same time massive floods were also eroding the Rock Creek drainage basin surface. However, volumes of flood water moving in the Clarks Fork valley greatly exceeded volumes of flood water moving in the Rock Creek drainage basin, although both were eroded by immense north-northeast oriented floods. Remaining maps follow the two drainage routes upstream into the high Beartooth Mountains to see where these massive floods were coming from. While melting of valley glaciers might account for some of floodwater, the volumes of water required to erode the deep Rock Creek and Clarks Fork valleys were much greater than any Beartooth Mountains valley glaciers could have produced. The floodwaters came from another source, north and west of the Beartooth Mountains.

West Fork Rock Creek-Lake Fork Rock Creek drainage divide area

Figure 4: West Fork Rock Creek-Lake Fork Rock Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the West Fork Rock Creek-Lake Fork Rock Creek drainage divide area south and west of figure 3 and includes a small overlap area in with figure 3.  Red Lodge is the town located near the figure 4 northeast corner. Rock Creek flows in a northeast, east, and north-northeast direction from the south center edge of figure 4 to Red Lodge. The Lake Fork of Rock Creek flows in an east direction from the west edge of figure 4 (just north of southwest corner) to join Rock Creek near the south center edge of figure 4. The West Fork of Rock Creek flows in a northeast, east-southeast and east-northeast direction from the west center edge of figure 4 to join Rock Creek just south of Red Lodge. The map contour interval for figure 4 is 50 meters. Note how Rock Creek and its West and Lake Forks have eroded deep canyons into the high Beartooth Mountains surface. The Silver Run Plateau is labeled in the west center region of figure 4 and the Red Lodge Plateau is located north of the deep West Fork canyon in the northwest corner of figure 4. The Hellroaring Plateau is located south of Lake Fork (just south of the west half of figure 4) while the Line Creek Plateau is located south of Rock Creek (just south of the east half of figure 4). These plateaus are not flat surfaces, but are sloping upland surfaces more than 1000 meters higher than the Rock Creek valley floor near Red Lodge. Immense volumes of water were required to erode the deep Rock Creek, West Fork, and Lake Fork canyons into the upland surfaces defined by the present day upland plateaus. The water came from south and west of figure 4 and before headward erosion of the deep Rock Creek, West Fork, and Lake Fork canyons was flowing across the upland plateau surfaces. Evidence of former flood flow channels can be found on the present day plateau surfaces. For example, note Wapiti Mountain north of where Lake Fork joins Rock Creek. Silver Run Creek flows in a north-northeast direction from west of Wapiti Mountain to join the West Fork Rock Creek while Sheep Creek flows in a southeast and south direction to join Rock Creek. Today there is a through valley, or notch, between Wapiti Mountain and the Silver Run Plateau linking the north oriented Silver Run Creek valley with the south oriented Sheep Creek valley. Figure 5 below provides a detailed topographic map of the drainage divide to better illustrate the through valley or notch. The through valley, or notch, was eroded as a north oriented flood flow channel to the actively eroding West Fork canyon at a time when the deep Rock Creek canyon south of Wapiti Mountain had not yet been eroded (but was probably being eroded headward by the same flood flow at that time).

Detailed map of Silver Run-Sheep Creek drainage divide area south of Horseshoe Mountain

Figure 5: Detailed map of Silver Run-Sheep Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 provides a detailed topographic map of the Silver Run-Sheep Creek drainage divide area seen in less detail in figure 4 above. Wapiti Mountain is located in the north half of section 26 (east half of figure 5). West of Wapiti Mountain in the north half of section 27 (near the center of figure 5) is the through valley (or notch) linking the north oriented Silver Run valley with the south oriented Sheep Creek valley. As seen in figure 4 Sheep Creek flows to east and northeast oriented Rock Creek while Silver Run flows to the east-northeast oriented West Fork Rock Creek. The map contour interval for figure 5 is 40 feet and the through valley (or notch) floor elevation at the drainage divide is between 9000 and 9040 feet. Wapiti Mountain rises to an elevation of 9436 feet, meaning the through valley (or notch) is approximately 400 feet deep. While today the through valley (or notch) appears to be an insignificant indentation in a high level mountain ridge it is a water eroded feature and was eroded by north oriented flood water flowing to what was once an actively eroding West Fork Rock Creek valley head. At that time there was no deep Rock Creek valley or canyon to the south and floodwaters could freely flow in a north direction to the actively eroding West Fork Rock Creek valley head. Floodwaters at that time were also flowing on the present day Rock Creek alignment and the deep Rock Creek valley (or canyon) was being actively eroded headward. In time headward erosion of the deep Rock Creek valley captured the north-oriented flood flow channel to the actively eroding Silver Run Creek valley. East oriented flood flow from west of the actively eroding Rock Creek valley head eroded the southeast and south oriented Sheep Creek valley before headward erosion of the deep Rock Creek valley and the deep West Fork Rock Creek (and tributary) valleys (west of figure 5) captured all flood flow.

Wyoming Creek-Line Creek drainage divide area

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

Figure 6 illustrates the Wyoming Creek-Line Creek drainage divide area south and slightly east of figure 4 and includes overlap areas with figure 4. Rock Creek flows in a northeast, east, and northeast direction from the west edge of figure 6 (near southwest corner) to the north edge of figure 6 (east half). Wapiti Mountain is located near the north center edge of figure 6. The Montana-Wyoming state line is a dashed line and extends across the south half of figure 6 and also serves as the Carbon County-Park County line. The Line Creek Plateau is labeled and is located near the center of figure 6. Wyoming Creek is a northeast and north-northwest oriented stream originating in Wyoming (in southwest quadrant of figure 6) and flowing along the Line Creek Plateau west margin to join Rock Creek. The deep north oriented valley along the figure 6 east margin is the Clarks Fork of the Yellowstone River valley and marks the Beartooth Mountains eastern margin. Line Creek originates south of the northeast oriented Wyoming Creek segment and flows in a northeast, southeast, and east direction to join the north oriented Clarks Fork of the Yellowstone River east of the southeast corner of figure 6. Note the east-northeast and southeast oriented Line Creek tributary originating near the Wyoming Creek elbow of capture (where Wyoming Creek turns from flowing in a northeast direction to flowing in a north-northwest direction) and the through valley linking that Line Creek tributary valley with the northeast oriented Wyoming Creek valley segment. The map contour interval is 50 meters and the through valley floor elevation at the drainage divide is between 3000 and 3050 meters. While the high point on the Line Creek Plateau is shown as 3083, meaning the through valley is at most 83 meters deep (and is probably shallower) the through valley is evidence of a former northeast oriented flood flow channel that existed prior to headward erosion of the deep north-northwest oriented Wyoming Creek valley. Figure 7 uses a detailed topographic to better illustrate the Wyoming Creek-Line Creek through valley.

Detailed map of Wyoming Creek-Line Creek drainage divide area

Figure 7: Detailed map of Wyoming Creek-Line Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 provides a detailed topographic map of the Wyoming Creek-Line Creek drainage divide area seen in less detail in figure 6 above. The Montana-Wyoming state line extends in a west to east direction across figure 7 and is labeled as the Carbon County-Park County line. Wyoming Creek flows in a northeast direction from near the southwest corner of figure 7 to near the state line and then turns to flow in a north-northwest direction to the north edge of figure 7. Line Creek is labeled and flows in a northeast direction from the south edge of figure 7 (west half) to the east edge of figure 7 (north half). An east-northeast oriented Line Creek tributary originates east of Line Lake, which is just north of the state line in section 27, and joins Line Creek east of figure 7. Note how that east-northeast oriented Line Creek tributary is linked by a through valley with the northeast oriented Line Creek valley segment. The map contour interval for figure 7 is 40 feet and the through valley floor elevation at the drainage divide is between 9880 and 9920 feet. The high point just north of the through valley is shown as being 10,116 feet while much higher elevations are seen south of the through valley. Today the through valley is approximately 100 feet deep and it is a water-eroded valley. South and east oriented floodwaters from north and west of figure 7 eroded the valley prior to headward erosion of the deep Rock Creek valley north and west of figure 7. Headward erosion of the deep Rock Creek valley north of figure 7 beheaded and reversed the south oriented flood flow and captured the east oriented flood flow, which then eroded the north oriented Wyoming Creek valley segment (see figure 6 for a bigger picture view). Continued headward erosion of the deep Rock Creek valley next beheaded and reversed the south and east oriented flood flow west of figure 7 to repeat the process and to erode the northwest oriented Chain Creek valley (from Twin Lakes) seen in figure 6. The process was repeated again further to the west of the Chain Creek valley to erode more deep north and northwest oriented Rock Creek tributary valleys into the high Beartooth Plateau (seen in southwest corner of figure 6). Immense quantities of water flowing in multiple flood flow channels characteristic of anastomosing flood flow channel complexes were required to erode the deep valleys and through valleys seen today. The big questions are where did these immense quantities of flood water come from and how did the floodwaters cross what is today a mountain range?

Rock Creek-Littlerock Creek drainage divide area

Figure 8: Rock Creek-Littlerock Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Rock Creek-Littlerock Creek drainage divide area south and west of the figure 6 map area and includes overlap areas with figure 6. The Montana-Wyoming state line is the labeled dashed line extending in a west to east direction across the north half of figure 8. Just north of the state line in the northwest quadrant of figure 8 is Glacier Lake. Rock Creek flows in a southeast direction from Glacier Lake into Wyoming and then turns to flow in a northeast direction to the north center edge of figure 8. Note the northwest oriented (and barbed) tributary joining Rock Creek at its elbow of capture (where it turns from flowing in a southeast direction to flowing in a northeast direction). Headward erosion of the deep northeast oriented Rock Creek valley captured a southeast oriented flood flow channel on the southeast oriented Rock Creek alignment to create the elbow of capture. The northwest oriented barbed tributary valley was eroded by a reversal of flood flow on the northwest end of the beheaded southeast oriented flood flow channel. At the time the elbow of capture was formed southeast oriented flood flow had probably already been captured further to the southeast by headward erosion of the deep unnamed northwest and north oriented Rock Creek tributary valley to the east (and before that by headward erosion of the deep north oriented Chain Creek valley and before that by headward erosion of the deep north oriented Wyoming Creek valley). However, before being captured by headward erosion of these deep north oriented Rock Creek valleys the southeast oriented floodwaters were flowing across what is now the high ridge on which the highway is located. A close look at that ridge reveals several shallow through valleys (or saddles), which are remnants of the southeast and south oriented flood flow channels that once crossed the region. Channels east of the Rock Creek elbow of capture lead to the deep Littlerock Creek valley. Gardner Lake, just south of the highway near the center of figure 8, is the headwaters of Littlerock Creek, which flows in a southeast and south direction before turning to flow in a southeast direction to Deep Lake and then in an east direction to the east edge of figure 8 and to the north oriented Clarks Fork of the Yellowstone River east of figure 8.

West of Deep Lake and slightly west of the south center edge of figure 8 is Sawtooth Lake, which is in the Canyon Creek drainage basin. Canyon Creek originates at Sheepherder Lake (north of the highway), which is linked by a through valley with the deep southeast oriented Rock Creek valley. Canyon Creek flows in a south-southwest direction from Sawtooth Lake to the south edge of figure 8 and to the southeast oriented Clarks Fork of the Yellowstone River valley south of figure 8 (the Clarks Fork of the Yellowstone River flows in a southeast direction south of figure 8 and then turns to flow in a north-northeast direction east of figure 8). The through valleys notched into the present day Rock Creek-Clarks Fork Yellowstone River drainage divide provide evidence of multiple south and southeast oriented flood flow channels that existed prior to headward erosion of the deep Rock Creek valley and which were captured by Rock Creek valley headward erosion, and which supplied the immense quantities of water required to erode the deep Rock Creek valley and its tributary valleys.

Detailed map of Rock Creek-Canyon Creek drainage divide area

Figure 9: Detailed map of Rock Creek-Canyon Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 provides a detailed topographic map of the Rock Creek-Canyon Creek drainage divide area seen in less detail in figure 8 above.  Rock Creek is labeled and can be seen near the north edge of figure 9 flowing in a southeast direction from the north edge (west of center and then turning to flow in a northeast direction to the north edge (near northeast corner of figure 9). Sheepherder Lake is located in section 35 (near south edge of figure 9) and is where south-southeast oriented Canyon Creek originates. Note the through valley linking the Sheepherder Lake basin with the deep Rock Creek valley. The map contour interval for figure 9 is 40 feet and the through valley floor elevation at the drainage divide is between 10,400 and 10,440 feet. Elevations to the southeast in the southeast corner of section 25 rise to more than 11,080 feet and elevations greater than 11,200 feet are found in section 22 (near northwest corner of figure 9). These elevations suggest the through valley is at least 640 feet deep. The through valley is a water-eroded feature, although valley glaciers probably have altered the regional landscape since the valley was first formed. Also note the Quintuple Peaks area in sections 19 and 30 slightly to the east of the through valley. The Quintuple Peaks are located between the deep valleys of a previously mentioned northwest oriented and barbed Rock Creek tributary and a northwest and north oriented Rock Creek tributary. The Quintuple Peaks are actually erosional remnants standing between deep flood-carved through valleys crossing the drainage divide between the two much deeper tributary valleys.

The entire Beartooth Plateau upland surface that today represents the high drainage divides seen in figure 9 is a flood-eroded erosion surface, which was eroded by southeast and south oriented floodwaters flowing across the region. Floodwaters at that time were flowing to a deep southeast oriented Clarks Fork valley and a deep south oriented flood flow channel east of the Beartooth Mountain. The deep east and northeast oriented Yellowstone River valley north of the Beartooth Mountains did not exist at that time and the Beartooth Mountains at that time did not stand high above regions to the north. Floodwaters were free to flow in a south and southeast direction from western Canada across Montana to and then across what was probably an emerging Beartooth Mountain mass. Beartooth Mountains uplift combined with headward erosion of the deep east and northeast oriented Yellowstone River valley (north of the rising Beartooth Mountains) and its deep northeast oriented tributary valleys (such as the deep Rock Creek valley) captured the south and southeast oriented flood flow. Floodwaters on the north end of the flood flow channels east of the emerging Beartooth Mountains mountain mass reversed flow direction to erode the deep north-northeast oriented Clarks Fork of the Yellowstone River valley segment and to capture the southeast oriented Clarks Fork of the Yellowstone River valley segment.

Lake Fork-Rock Creek drainage divide area

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

Figure 10 illustrates the Lake Fork-Rock Creek drainage divide area north and west of figure 8 and includes overlap areas with figure 8 (the figure 10 map is enlarged).  Lake Fork originates near the northwest corner of figure 10 and flows in a southeast, northeast, and east direction near the north edge of figure 10 to the northeast corner. Rock Creek flows in a southeast direction from Glacier Lake before turning at the south edge of figure 10 to flow in a northeast direction to the east center edge of figure 10. Hellroaring Creek originates at Sliderock Lake (east of the center of figure 10) and flows in an east direction to join Rock Creek near the east center edge of figure 10. The Hellroaring Plateau is located between Lake Fork Rock Creek and Hellroaring Creek and Mount Rearguard is located at the west end of the Hellroaring Plateau. West of Sliderock Lake and south of Mount Rearguard is Moon Lake where a southeast and south-southeast oriented Rock Creek tributary originates. North of Moon Lake is a through valley between Mount Rearguard and Spirit Mountain linking the south oriented Rock Creek tributary valley with a northeast oriented tributary valley draining to Lake Fork. The map contour interval for figure 10 is 50 meters and the elevation of Mount Rearguard is 3720 meters and the Spirit Mountain elevation is 3744 meters. The through valley floor elevation at the drainage divide is between 3350 and 3400 meters or more than 300 meters lower than the adjacent mountain peaks. The through valley was eroded as a southeast oriented flood flow channel, which can be followed headward, or to the northwest, between Thunder Mountain and Beartooth Mountain. The sequence of capture events recorded along this southeast oriented flood flow channel is headward erosion of the deep northeast oriented Rock Creek valley first captured the flood flow channel (which at one time led to an actively eroding southeast oriented flood flow channel on the southeast oriented Clarks Fork of the Yellowstone River alignment). Next the deep southeast oriented Rock Creek tributary valley eroded headward to the Moon Lake location. When the southeast oriented tributary valley head reached the Moon Lake location headward erosion of the deep northeast oriented Lake Fork tributary valley beheaded the flood flow channel. Finally headward erosion of the deep Lake Fork valley west of Thunder Mountain and Beartooth Mountain captured the southeast oriented flood flow and diverted floodwaters in an east direction to the Rock Creek valley. Beartooth Mountains uplift was probably occurring as floodwaters flowed across the region. At a later time valley glaciers formed in the valleys and further modified the figure 10 landscape.

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.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: