Teton River-Sun River drainage divide area landform origins, western Teton County, Montana, USA

Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Teton River-Sun River drainage divide area located in western Teton County. Western Teton County is a region of high mountains just east of the east-west continental divide while eastern Teton County is a plains region east of the mountain front. The Teton River and Sun River are east-oriented rivers originating along northern Montana’s east-west continental divide and flowing onto the Montana plains to join the Missouri River with the Teton River north of the Sun River. Missouri River water eventually reaches the Gulf of Mexico. The south-oriented North Fork Sun River is linked by a deep through valley at Sun Pass with northwest-oriented drainage to the south-oriented Flathead River, water in which eventually reaches the Pacific Ocean. Other well-defined and deep north-south oriented through valleys link north-oriented Teton River tributary valleys with south-oriented Sun River tributary valleys and also cross drainage divides between east-oriented Teton River tributaries. The north-south oriented through valleys, which are found both east and west of the continental divide and some of which cross the continental divide, were eroded by immense south-oriented melt water floods derived from a rapidly melting thick North American ice sheet. The ice sheet had been located in a deep “hole” and huge ice marginal melt water floods from the Canada flowed in south directions along the deep “hole’s” western rim, which is now the location of the Canadian and northern Montana Rocky Mountains. What were diverging and converging anastomosing flood flow channels were captured in sequence from south to north as deep valleys eroded headward from both the east and west into what was probably a rising mountain region to carve the present day east-west continental divide. North and northwest-oriented valleys were eroded by massive flood flow reversals on north ends of south-oriented flood flow channels which were beheaded by much deeper east- and west-oriented valleys. Teton River valley headward erosion beheaded flood flow to the newly eroded Sun 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 available at this site may be found by selecting desired Missouri River tributaries and/or states from this essay’s sidebar category list.

Introduction:

  • The purpose of this essay is to use topographic map interpretation methods to explore the Teton River-Sun River drainage divide area landform origins in western Teton County, Montana, 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 providing 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 essays in the Missouri River drainage basin landform origins research project 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 Teton River-Sun River drainage divide area landform evidence in western Teton County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see link to essay about paradigm above title). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Teton River-Sun River drainage divide area location map

Figure 1: Teton River-Sun 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 Teton River-Sun River drainage divide area in western Teton County, Montana and shows a region in northwest and north central Montana. The Canadian border is located along the figure 1 north edge. Glacier National Park is located near the figure 1 northwest corner. The east-west continental divide extends in a south-southesat direction from Logan Pass and Marias Pass in Glacier National Park along and slightly west of the Lewis and Clark Range crest to the figure 1 south edge (west of Helena). Water in drainage routes west of the continental divide eventually reaches the Pacific Ocean. The northwest-oriented Middle Fork Flathead River and north-northwest oriented South Fork Flathead River and Swan River flow to the south-oriented Flathead River, which flows through Flathead Lake to join northwest-oriented Clark Fork west of the figure 1 map area. Northwest-oriented Clark Fork can be seen flowing through Missoula in the figure 1 southwest corner region. East of the continental divide with the exception of a small region near the Canadian border in eastern Glacier National Park all drainage routes eventually lead to the Missouri River with water eventually reaching the Gulf of Mexico. The St Mary River flows north into Canada from St Mary Lake on the Glacier National Park east edge with water eventually reaching Hudson Bay. The Missouri River flows in a north-northwest direction from the figure 1 south center edge (east of Helena) and near Wolf Creek turns to flow in a northeast direction to Great Falls, Fort Benton, and Loma. South of Big Sandy the Missouri River makes an abrupt turn to flow in a south-southeast and east direction to the figure 1 east center edge. The Sun River is an east-oriented tributary originating along the continental divide and then flowing onto the Montana plains to join the Missouri River at Great Falls. The Teton River is north of the Sun River and is also an east-oriented tributary originating along the continental divide and joining the Missouri River near Loma. The Teton River-Sun River drainage divide area in western Teton County is located in the mountains where the Teton and Sun Rivers begin and is bounded on the west by the continental divide, the north by the Teton River, the south by the Sun River, and the east by the mountain front. The Teton River-Sun River drainage divide area landform origins eastern Teton County, Montana essay describes the region immediately to the east. The Birch Creek-Teton River drainage divide area landform origins, Pondera and Teton Counties, Montana essay describes the region to the north. Essays describing Teton and Sun River drainage divide areas are listed under the Teton River and Sun River categories shown on the sidebar category list.
  • While today the Teton River-Sun River drainage divide area in western Teton County, Montana is a region of high mountains the topographic map evidence shown in this essay demonstrates the drainage divide area was eroded by immense south and southeast-oriented floods. Based on topographic map evidence from hundreds of other essays describing other Missouri River drainage basin drainage divide areas and included in the Missouri River drainage basin landform origins research project flood waters eroding the Teton River-Sun River drainage divide area were derived from a rapidly melting thick North American ice sheet, which was located in a deep “hole.” The deep “hole” did not exist when the ice sheet was formed, but instead evolved as deep glacial erosion scoured regions under the ice sheet at the same time as crustal warping raised mountain ranges and high plateau elsewhere on the North American continent. Today the upper Missouri River drainage basin in Montana and northern Wyoming and the Saskatchewan River drainage basin in southwest Alberta represent the deep “hole’s” deeply eroded west and southwest wall. The Canadian and northern Montana Rocky Mountains represent a segment of the deep “hole’s” western rim. When ice sheet melting began the ice sheet stood high above this deep “hole” western rim and south and southeast-oriented ice-marginal melt water floods could flow freely along what are today the crests of high mountain ranges. These immense melt water floods flowed in south and southeast direction across Montana and continued into Wyoming, Colorado and even into New Mexico along what are present day high Rocky Mountain ranges. Rocky Mountain uplift occurred as massive south and southeast-oriented floods were flowing across the region and began in the south and proceeded to the north and northwest. At the same time deep east and west-oriented valleys (e.g. Rio Grande, Arkansas, and North Platte from the east and Colorado from the west) eroded headward into the rising Rocky Mountain region to capture the immense south and southeast-oriented melt water floods.
  • In time lowering of the ice sheet surface, especially along the ice sheet southern margin, combined with Rocky Mountain and other ice marginal region uplift created a situation where elevations on the ice sheet surface were lower than elevations on the south and southeast oriented melt water flood flow routes. Giant south oriented ice-walled canyons were carved by huge supra-glacial melt water rivers into the decaying ice sheet’s surface and became the major regional drainage routes. Large east and northeast-oriented valleys then eroded headward from these ice-walled canyons into the adjacent ice-marginal bedrock regions to capture the massive south and southeast-oriented ice-marginal melt water floods. These valleys eroded headward in sequence from the southeast to the northwest with each successive valley beheading flood flow routes to the newly eroded valley to the southeast. For example, headward erosion of the deep northeast-oriented Yellowstone River valley occurred prior to Missouri River-Musselshell River valley headward erosion, which beheaded south and southeast-oriented flood flow to the newly eroded Yellowstone River valley. In central and western Montana these deep valleys also captured south- and southeast-oriented melt water floods from Canada which had become trapped by rising Rocky Mountain ranges. Some of these trapped flood waters flowed into southwest Montana where further south and southeast flow was blocked by rising mountains forcing the flood waters to flow in north directions to reach the deep Yellowstone and Missouri River valleys. Massive flood flow reversals resulted in north and northwest-oriented Missouri River valley segments and tributary valleys such as those seen in the figure 1 southeast quadrant (e.g. north-northwest Missouri River segment and Smith River). East-oriented Missouri River tributary valleys such as the Sun River valley and the Teton River valley were also eroded in sequence with the headward erosion of the Teton River valley beheading flood flow to what was then the newly eroded Sun River valley. West of the continental divide headward erosion of deep valleys from the Pacific Ocean beheaded and reversed southeast- and south-oriented flood flow channels to erode north- and northwest-oriented drainage routes (e.g. Clark Fork, Middle and South Forks Flathead River, and Swan River). Headward erosion of these deep valleys from both the east and west gradually carved the east-west continental divide, again from the south to the north.

Detailed location map for Teton River-Sun River drainage divide area

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

 

  • Figure 2 provides a detailed location map for the Teton River-Sun River drainage divide area in western Teton County, Montana. County boundaries are shown and Teton County is labeled. Pondera County is north of Teton County, Cascade County is located in the figure 2 southeast corner, and Lewis and Clark County is west of Cascade County and south of Teton County with a narrow northwest extension west of southern Teton County. West of Teton County and Lewis and Clark County is Flathead County with the Flathead County eastern border being defined by the east-west continental divide. West of the continental divide the northwest-oriented Middle Fork Flathead River flows to the figure 2 northwest corner. The South Fork Flathead River flows in a north-northwest direction to Hungry Horse Reservoir (the lake seen along the figure 2 west edge just south of the northwest corner). The South Fork and Middle Fork Flathead River join north and west of the figure 2 map area with the south oriented North Fork Flathead River to form the south-oriented Flathead River. Note how both the north-oriented Middle and South Forks Flathead River have south-oriented tributaries providing evidence of former south-oriented flood flow channels across the region. The north-oriented Middle and South Fork Flathead River valleys were eroded by massive flood flow reversals when south-oriented flood flow channels were beheaded by headward erosion of the much deeper south-oriented Flathead River valley. East of the continental divide the North Fork Sun River originates at Sun River Pass (not labeled in figure 2 but located near the northern tip of the Lewis and Clark County northwest extension) and then flows in a south direction along the Lewis and Clark-Teton County boundary to join the north-oriented South Fork Sun River to form the Sun River which flows in an east direction along the Teton County-Lewis and Clark boundary to the figure 2 southeast corner region where the county boundary makes a northward jog and the Sun River continues in an east direction into Cascade County. The south- and east-oriented West Fork Sun River is located in the figure 2 southwest corner region and joins the north-oriented South Fork Sun River shortly before the South Fork joins the North Fork. The north-oriented South Fork Sun River valley was eroded by a massive flood flow reversal on what had been a south-oriented flood flow channel which was beheaded by headward erosion of the much deeper east-oriented Sun River valley. The barbed West Fork Sun River route was established by capture of a south-oriented flood flow channel west of the south-oriented North Fork-South Fork Sun River flood flow channel. The North Fork Teton River originates near Mt Patrick Gass in the Teton County northwest corner and flows in a south-southeast direction to near Cave Mountain where it turns to flow in an east and southeast direction to Choteau and then turns to flow in a northeast and east direction to the figure 2 east edge. East of the south-oriented North Fork Sun River in the Teton County southwest corner are headwaters of east-oriented North and South Fork Deep Creek, which join near Long Ridge to form east and east-northeast oriented Deep Creek. Note how Deep Creek joins the Teton River near Choteau. Deep Creek is the southernmost of the Teton River tributaries and will be seen in the topographic maps below.

Bowl Creek-Fool Creek drainage divide area at Sun River Pass

Figure 3: Bowl Creek-Fool Creek drainage divide area at Sun River Pass. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

 
  • Figure 3 illustrates the Bowl Creek-Fool Creek drainage divide area at Sun River Pass, which is a major through valley eroded across the east-west continental divide. Sun River Pass is located near the figure 3 center at the point where Flathead, Teton, and Lewis and Clark Counties meet. The Flathead County border is defined by the east-west continental divide with surface drainage in Flathead County flowing to the Flathead River and eventually reaching the Pacific Ocean. Teton and Lewis and Counties are located in the Missouri River drainage basin with surface drainage eventually reaching the Gulf of Mexico. Bowl Creek flows in a west-southwest direction south of Bowl Mountain in the figure 3 northeast quadrant to the Sun River Pass area and then turns to flow in a northwest direction to join the northwest-oriented Middle Fork Flathead River, which flows to the figure 3 north edge (west half). Note how north of Sun River Pass the Bowl Creek valley is linked by a through valley with a north-northwest oriented South Fork Trail Creek and Trail Creek valley segment which drains to a south oriented Middle Fork Flathead River tributary as a barbed tributary (Strawberry Creek, the south oriented Middle Fork Flathead tributary, is another excellent example of a barbed tributary). South of Sun River Pass are headwaters of south-oriented Fool Creek which joins east-oriented Open Creek to flow to south-oriented McDonald Creek to form the south-oriented North Fork Sun River. South-oriented Wrong Creek and Nesbit Creek in the figure 3 southeast quadrant are North Fork Sun River tributaries. North of south-oriented Nesbit Creek headwaters are the north-oriented Olney Creek and Porcupine Creek headwaters which flow to the south- and east-oriented West Fork Teton River, which joins the south-southeast oriented North Fork Teton River just east of the figure 3 map area. The, through valleys, elbows of capture, and barbed tributaries, which are common landform features in the figure 3 map area, were formed during massive south and south-southeast floods, which once crossed the figure 3 map area and then were beheaded and reversed by headward erosion of much deeper valleys. Sun River Pass is a through valley in what was at that time was a major south-oriented flood flow channel, which was captured south of the figure 3 map area by headward erosion of the deep east-oriented Sun River valley. Headward erosion of the deep Flathead River valley (north and west of figure 3) next beheaded south- and southeast-oriented flood flow routes leading to the Sun River Pass through valley. The result was a massive flood flow reversal, which enabled reversed flood flow on what had been the south-oriented Middle Fork Flathead River flood flow channel (supplying flood water to the newly eroded Sun River valley) to capture all south-oriented flood flow channels north of Sun River Pass. Probably at the same time headward erosion of the deep east-oriented Teton River valley (north of the newly eroded east-oriented Sun River valley) captured south-oriented flood flow channels east of the Sun River Pass through valley and flood waters on north ends of beheaded flood flow channels reversed flow direction to erode north-oriented West Fork Teton River tributary valleys as seen in the figure 3 east center edge area.

Detailed map of Bowl Creek-Fool Creek drainage divide area at Sun River Pass

Figure 4: Detailed map of Bowl Creek-Fool Creek drainage divide area at Sun River Pass. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 4 provides a detailed topographic map of the Bowl Creek-Fool Creek drainage divide area at Sun River Pass to better illustrate the Sun River Pass through valley. The county boundaries are clearly shown and labeled with Flathead County being west of the east-west continental divide and Teton and Lewis and Clark Counties being east of the continental divide. Note how the continental divide in this region is more of an east-west line than of a north-south line. Sun River Pass is located in the figure 4 northeast quadrant where Teton, Lewis and Clark, and Flathead Counties meet. Basin Creek is the east-northeast oriented stream flowing from the figure 4 west center edge and turning to flow in a north-northwest direction north of Sun River Pass. Bowl Creek flows in a southwest and northwest direction in sections 36 and 35 of the figure 4 northeast quadrant and is joined by Basin Creek just north of figure 4. North of the figure 4 map area Bowl Creek flows in a northwest direction to join south oriented Strawberry Creek to form the northwest oriented Middle Fork Flathead River. South of Sun River Pass Fool Creek flows in an east-northeast direction to the section 11 northeast corner and then turns to flow in south direction in the large north-south oriented valley to the figure 4 south edge (east half). South of the figure 4 Fool Creek joins Open Creek to form the south-oriented North Fork Sun River. The figure 4 map contour interval is 40 feet and the Sun River Pass elevation at the drainage divide is between 6120 and 6160 feet. Elevations in the Basin Creek valley in section 35 to the north are less than 5800 feet and in the Fool Creek valley in the section 11 northeast corner to the south are less than 6000 feet meaning Sun River Pass is by no mean a level through valley. However elevations on Porphyry Reef to the east rise to 7780 feet and on the unlabeled mountain near the figure 4 southwest corner rise to 8060 feet. While the Sun River Pass elevation is more than 300 feet higher than the Basin Creek valley just to the north it is also at least 1600 feet lower than tops of the surrounding mountain tops. This large north-south oriented through valley was eroded by south-oriented flood flow, which was subsequently beheaded by a massive flood flow reversal north of Sun River Pass. Why is the Basin Creek (and the Bowl Creek) valley to the north deeper than the Fool Creek valley to the south? Basin Creek headwaters are located west of the figure 4 map in a high mountainous area, but are linked by a deep mountain pass (or through valley) with the north-oriented Clock Creek valley. Clock Creek is today a Middle Fork Flathead River tributary, but for a time after the flood flow reversal north of Sun River Pass south-oriented flood flow continued to move on the Clock Creek alignment and eroded the deep Basin Creek valley. This interpretation requires deep flood water erosion of valleys by both south- and (reversed) north-oriented flood flow at a time when deep valleys were eroding headward into what must have been a rising mountain region. The east-northeast oriented Basin Creek valley alignment was initiated as a diverging southwest-oriented flood flow route leading to the northwest and west-oriented Spotted Bear River valley, which leads to today to the north-northwest oriented South Fork Flathead River valley, but which previously was an east-southeast oriented flood flow channel.

Teton River-Sun River drainage divide area

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

 

  • Figure 5 illustrates the Teton River-Sun River drainage divide area south and east of the figure 3 map area and includes overlap areas with figure 3. Sun River Pass is located near the figure 5 northwest corner. Fool Creek and the North Fork Sun River flow in a south-southeast direction from Sun River Pass to the figure 5 south edge (west half). North Fork Sun River tributaries from the east (from north to south) include south-oriented McDonald Creek, south-oriented Wrong Creek, southwest-oriented Roule Creek, and west-southwest oriented Ray Creek. Nesbitt Creek is a south-oriented tributary to southwest-oriented Roule Creek. Note how south-oriented Wrong Creek has a north-oriented barbed tributary. The North Fork Teton River flows in a south-southeast direction from the figure 5 north edge (east half) and then turns to flow in an east-southeast direction to the figure 5 east center edge. The east-oriented West Fork Teton River joins the south-southeast oriented North Fork Teton River near the figure 5 north edge. Olney Creek and Nesbitt Creek are north-oriented tributaries to the east-oriented West Fork Teton River. Note how north-oriented Olney Creek is linked by a deep through valley (or mountain pass) with south-oriented Nesbit Creek providing evidence of a former south-oriented flood flow channel which was beheaded and reversed by West Fork Teton River headward erosion. Figure 6 provides a detailed topographic map of the Olney Creek-Nesbit Creek through valley area. South of the West Fork Teton River the North Fork Teton River tributaries (from north to south) are east-northeast oriented Waldron Creek, east-northeast and east oriented Middle Fork Teton River, and the northeast and east-oriented South Fork Teton River, which joins the North Fork just east of figure 5 to form the east-oriented Teton River. Note how east-oriented North Fork Teton River tributary valleys are linked by north-south oriented through valleys providing evidence of multiple south-oriented flood flow channels, which deeply the eroded the western Teton River drainage basin. The figure 5 map contour interval is 50 meters and the deepest through valleys between the Waldron Creek and Middle Fork Teton River valleys have elevations of between 1950 and 2000 meters while mountains along the drainage divide on both sides rise to elevations of 2299 meters in the east and 2565 meters in the west. The deepest through valley eroded across Lonesome Ridge (between the Middle Fork and South Fork Teton River) has an elevation at the drainage divide of between 1850 and 1900 meters while elevations greater than 2200 meters can be found on either side. These and other similar through valleys in figure 5 provide evidence of south-oriented flood flow channels which were first beheaded and reversed by headward erosion of the deep South Fork Teton River valley, next by headward erosion of the deep Middle Fork Teton River valley, still later by headward erosion of the deep Waldron Creek (and its northeast-oriented tributary) valley, and finally by headward erosion of the deep North Fork and West Fork Teton River valley. At the time flood water flowed across the figure 5 map area the mountains did not stand high above the Montana plains to the east. Either the plains were deeply eroded by the massive floods or the mountains were rising as the floods flowed across the region. Probably both events occurred with both deep erosion of the plains and mountain uplift occurring at the same time.

Detailed map of Olney Creek-Nesbit Creek drainage divide area

Figure 6: Detailed map of Olney Creek-Nesbit Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 6 is a detailed topographic map of the Olney Creek-Nesbit Creek drainage divide area seen in less detail in figure 5 above. North-oriented Olney Creek flows from sections 14 and 15 to the figure 6 north center edge. North of figure 6 Olney Creek joins the east-oriented West Fork Teton River. South-oriented Nesbit Creek originates near the south edge of section 14 and flows across section 23 to the figure 6 south center edge. South of figure 6 Nesbit Creek flows to southwest-oriented Roule Creek, which then joins the south-oriented North Fork Sun River. Note how the north-oriented Olney Creek valley is linked to the south-oriented Nesbit Creek valley by two adjacent and deep north-south oriented through valleys (or mountain passes). The figure 6 map contour interval is 40 feet and the deeper through valley elevation at the drainage divide is between 7280 and 7320 feet. Mount Lockhart to the east rises to 8691 feet while near the center of section 15 to the west a spot elevation of 8051 feet is shown on the high ridge. These elevations suggest the deeper through valley is at least 700 feet deep and the second (western) through valley is almost as deep. These two through valleys are water eroded features and were eroded by south-oriented flood flow at a time when the deep east-oriented West Fork Teton River valley to the north did not exist. Flood waters were flowing on a surface higher than the Olney Creek-Nesbit Creek drainage divide today to the actively eroding south-oriented Nesbit Creek valley, which at that time was eroding headward from what was then the newly eroded south-oriented North Fork Sun River valley. Headward erosion of the deep east-oriented West Fork Teton River valley beheaded the south-oriented flood flow channel and flood waters on the north end of the beheaded flood flow channel reversed flow direction to erode the north-oriented Olney Creek valley. Probably the situation was much more complicated with south-oriented flood waters from west of the figure 6 map area being captured by the newly reversed and actively eroding north-oriented Olney Creek valley. At that time deep valleys seen in the west half of figure 6 had yet to be eroded and flood waters were still flowing on a surface equivalent to the level of the high ridges seen today. Through valleys (or mountain passes) eroded across those high ridges probably were eroded by the south-oriented flood waters from further to the west as they moved to both the actively eroding south-oriented Nesbit Creek valley and the newly reversed and actively eroding Olney Creek valley. It is difficult to imagine flood waters flowing on the tops of the high mountains today, which probably means the figure 6 map area was not a region of high mountains at that time. Probably the region was being uplifted as flood waters were eroding what are now deep valleys in the present day mountain area and at the same time lowering the Montana plains to the east of the mountain front.

South Fork Teton River-South Fork Deep Creek drainage divide area

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

 

  • Figure 7 illustrates the South Fork Teton River-South Fork deep Creek drainage divide area south and east of figure 5 and includes overlap areas with figure 5. The south-oriented North Fork Sun River is located near the figure 7 west edge. The north-south oriented Sawtooth Range located just west of the figure 7 center marks the drainage divide between the south-oriented North Fork Sun River and the Teton River drainage basins. The South Fork Teton River originates along the east side of the Sawtooth Range near the figure 7 north edge and flows in a north, northeast, east and northeast direction to the figure 7 north edge (east half). Labeled north-oriented tributaries east of the north-oriented South Fork headwaters include Green Gulch, Rierdon Gulch, and Bear Gulch. South of the north-oriented South Fork Teton River, Green Gulch, and Rierdon Gulch headwaters are south-oriented headwaters and tributaries flowing to the east-southeast and southeast oriented North Fork Deep Creek which flows the figure 7 southeast corner. Originating just west of the Sawtooth Range crest line and flowing in an east direction along the figure 7 south edge is the South Fork Deep Creek. Note how the north-oriented South Fork Teton River headwaters and tributary valleys are linked by through valleys with the south-oriented North Fork Deep Creek headwaters and tributary valleys. The North and South Forks Deep Creek join just south of the figure 7 southeast to form Deep Creek which eventually joins the Teton River. Note how unlabeled north-oriented North Fork Deep Creek tributary valleys are linked by through valleys with south-oriented South Fork Deep Creek tributary valleys. Also note how the South Fork Deep Creek headwaters valley is linked by a deep north-south oriented through valley with the north-oriented headwaters valley of west-oriented Biggs Creek, which flows to the south-oriented North Fork Sun River. Study of figure 7 reveals many additional north-south oriented through valleys. These through valleys probably were eroded along zones of geologic weakness, although they are all water eroded features and were eroded by multiple south-oriented flood flow channels initiated prior to headward erosion of the deep South Fork Deep Creek valley which first captured the south-oriented flood flow. Next headward erosion of the deep North Fork Deep Creek valley beheaded and reversed the south-oriented flood flow channels to erode north-oriented tributary valleys in sequence from east to west. Finally in the figure 7 east half headward erosion of the deep South Fork Teton River valley beheaded and reversed the south-oriented flood flow channels to erode its north-oriented headwaters and tributary valleys as it eroded headward into the region. At the same time the deep south-oriented North Fork Sun River valley was eroding headward along a major south-oriented flood flow channel and the west-oriented Biggs Creek valley eroded headward toward the emerging Sawtooth Range to behead and reverse a south-oriented flood flow channel, which had been captured by headward erosion of the South Fork Deep Creek valley. The Sawtooth Range emerged as flood waters eroded deep valleys around it. Probably mountains in the entire figure 7 map area were being uplifted at the time.

Detailed map of Green Gulch-Sheep Gulch drainage divide area

Figure 8: Detailed map of Green Gulch-Sheep Gulch 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 Green Gulch-Sheep Gulch drainage divide area seen in less detail in figure 7 above. North-oriented drainage flowing to the figure 8 north edge flows to the east oriented South Fork Teton River. South and southwest-oriented drainage in the figure 8 southwest corner region flows to west-oriented Biggs Creek and the south-oriented North Fork Sun River. Remaining south-oriented drainage flowing to the figure 8 south edge flows to the east- and southeast-oriented North Fork Deep Creek with water eventually reaching the Teton River. South-oriented drainage originating in the section 28 south half is the headwaters of North Fork Deep Creek, which turns to flow in an east direction south of the figure 8 map area. Sheep Gulch originates near the south edge of section 27 and flows in a south direction through section 34 to join the North Fork Deep Creek south of the figure 8 map area. Slim Gulch originates near the south edge of section 23 and flows in a south direction through sections 26 and 35 to join the North Fork Deep Creek south of the figure 8 map area. The north-oriented stream originating in section 28 is the South Fork Teton River, which north of the figure 8 map area flows in an east direction. Green Gulch originates near the north edge of section 27 and flows in a north direction across the west half of section 22 to join the South Fork Teton River north of the figure 8 map area. Rierdon Gulch originates in section 23 and flows in a north direction to join the South Fork Teton River north of the figure 8 map area. Note the three closely spaced through valleys (or mountain passes) in section 27 linking the north-oriented Green Gulch valley with the south-oriented Sheep Gulch valley. The figure 8 contour interval is 40 feet and all three through valleys have floor elevations at the drainage divide of between 7120 and 7160 feet. The high point on the ridge to the east is shown as 8462 feet while the high point on the ridge to the west is shown as 8040 feet. Further west a mountain in the Sawtooth Range is shown with an elevation of 9147 feet. Depending on which elevations are used for markers the Green Gulch-Sheep Gulch through valley is at least 900 feet deep and may document much deeper flood water erosion of the region. The Rierdon Gulch-Slim Gulch through valley in section 23 has a valley floor elevation at the drainage divide of between 7560 and 7600 feet. The ridge immediately to the west is shown as rising to 8462 feet while the ridge immediately to the east rises to more than 8160 feet. East of the figure 8 map area Ear Mountain rises to 8580 feet. Again depending which elevations are used the Rierdon Gulch-Slim Gulch through valley documents at least 560 feet of flood water erosion and may document much deeper flood water erosion in the figure 8 map region. These through valleys and other through valleys seen in figure 8 are water eroded features and were eroded by adjacent south-oriented flood flow channels, which were components of a large-scale south-oriented anastomosing channel complex, which deeply eroded the figure 8 map area as the deep east-oriented South and North Forks of Deep Creek eroded headward into the figure 8 map area to capture south-oriented flood flow.

South Fork Deep Creek-Sun River drainage divide area

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

 

  • Figure 9 illustrates the South Fork Deep Creek-Sun River drainage divide area south of figure 7 and includes overlap areas with figure 7. The change from the mountains to the plains can be seen in the figure 9 east half. The North Fork Sun River flows in a south and south-southeast direction from the figure 9 northwest corner to Medicine Springs (a place near the figure 9 southwest corner) where it joins the north oriented South Fork Sun River to form the southeast and east-northeast oriented Sun River which flows near the figure 9 south edge to the figure 9 east edge (south half). Gibson Reservoir is the lake flooding the southeast-oriented Sun River valley immediately downstream from Medicine Springs. Labeled south oriented Sun River tributaries from west to east are Big George Gulch, Mortimer Gulch, and Hannan Gulch. Note how the south- and east-oriented Blacktail Gulch headwaters originate west of the main Blacktail Gulch valley and how the south-oriented headwaters valley is linked by a deep north-south oriented through valley with the south-oriented Big George Gulch valley. Also note how a trail from the Mortimer Gulch headwaters valley goes over a low mountain pass (or through valley) and enters a northeast-oriented valley leading to the south-oriented Blacktail Gulch valley. South Fork Deep Creek originates just north of south-oriented headwaters of the south- and east-oriented Blacktail Gulch headwaters (which begin north of Big George Gulch). Note how north- and south-oriented valleys draining to the east-oriented South Fork Deep Creek headwaters are linked by through valleys to both the south-oriented Blacktail Gulch headwaters valley segment and a north-oriented stream valley near the figure 9 north edge. From its headwaters area the South Fork Deep Creek flows in an east direction to the figure 9 east edge (north half). Remember east of the figure 9 map area Deep Creek eventually joins the Teton River. Note how short north-oriented tributary valleys draining to the east-oriented South ForK Deep Creek valley are linked by north-south oriented through valleys to south-oriented Sun River tributary valleys. The north-south oriented through valleys seen in figure 9, while probably also related to the underlying geology, were eroded initially as south-oriented anastomosing flood flow channels in what was at one time an immense south-oriented anastomosing channel complex. At first the south-oriented flood waters were flowing on a surface equivalent to the highest figure 9 elevations today and the deep north-south oriented valleys were eroded as deep east-oriented valleys eroded headward into the figure 9 map area. Headward erosion of the deep east-oriented Sun River valley captured the south-oriented flood flow first and deep south-oriented Sun River tributary valleys eroded headward from the newly eroded Sun River valley north wall. Subsequently headward erosion of the deep east-oriented South Fork Deep Creek valley beheaded what were by that time well-defined and deep south-oriented flood flow channels and flood waters on north ends of the beheaded flood flow channels reversed flow direction to erode the north-oriented South Fork Deep Creek tributary valleys. At the same time uplift in the mountain area and/or deep flood water erosion of the plains area along the figure 9 east margin were creating the elevation differences seem today.

Detailed map of South Fork Deep Creek-Blacktail Gulch drainage divide area

Figure 10: Detailed map of South Fork Deep Creek-Blacktail Gulch 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 South Fork Deep Creek-Blacktail Gulch drainage divide area seen in less detail in figure 9 above. The South Fork Deep Creek flows in an east direction from the figure 10 west edge (section 20) to the figure 10 east edge (near northeast corner). East of the figure 10 map area Deep Creek eventually flows to the Teton River. Blacktail Gulch originates in section 27 and drains in a south direction almost to the figure 10 southwest corner where it turns to flow in an east direction to the section 33 southeast corner and to flow in a south direction to the figure 10 south edge. South of figure 10 Blacktail Gulch eventually drains to the east-oriented Sun River. The south-oriented stream originating in the section 27 southeast corner and the section 26 southwest corner and draining in a south direction along the section 34 and section 35 boundary is Hannan Gulch, which also drains to the east-oriented Sun River (south of the figure 10 map area). The south-oriented stream in the figure 10 southeast corner is Green Timber Gulch which south and east of figure 10 turns to flow in an east and northeast direction with water eventually reaching Deep Creek. North of the Green Timber Gulch headwaters is north-oriented No Business Creek, which flows to east-oriented South Fork Deep Creek. Note how deep and well-defined north-south oriented through valleys link the north-oriented South Fork Deep Creek tributary valleys with the south-oriented Green Timber Gulch headwaters and with the south-oriented Hannan Gulch and Blacktail Gulch valleys. The figure 10 map contour interval is 40 feet and the through valley near the south edge of section 29 (near figure 10 west edge) has a floor elevation at the drainage divide of between 7520 and 7560 feet. Mountain peaks both east and west of the through valley rise to more than 8400 feet suggesting the through valley may have been an 800 foot deep south-oriented flood flow channel. Proceeding east along the drainage divide to the southwest corner of section 29 another through valley has a drainage divide floor elevation of between 7960 and 8000 feet suggesting it was once a 400 foot deep south-oriented flood flow channel. Continuing east to the section 28 southeast quadrant there is a broader through valley with a drainage divide elevation of between 7560 and 8000 feet, again suggesting at one time the presence of an 800 foot deep south-oriented flood flow channel. Near the west center edge of section 27 a much deeper through valley links the main south-oriented Blacktail Creek valley segment with a north-oriented South Fork Deep Creek tributary valley. This deeper through valley has an elevation at the drainage divide of between 6880 and 6920 feet suggesting it once may have been a 900 foot deep south-oriented flood flow channel. Additional through valleys can be seen further to the east. The through valleys and the north-south valley orientations suggest the region was eroded by massive south-oriented flood flow which was captured by headward erosion of a very deep east-oriented Sun River valley with deep south-oriented (and probably anastomosing) flood flow channels eroding headward into a high level surface equivalent in elevation to the highest figure 10 elevations today. Headward erosion of a very deep east-oriented South Fork Deep Creek valley beheaded the south-oriented flood flow channels in sequence from east to west. Flood waters on north ends of beheaded flood flow channels reversed flow direction to erode the north-oriented South Fork Deep Creek tributary valleys.

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

Follow

Get every new post delivered to your Inbox.

%d bloggers like this: