Cut Bank Creek-Two Medicine River drainage divide area landform origins, Glacier County, Montana, USA

Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Cut Bank Creek-Two Medicine River drainage divide area of Glacier County, Montana. Cut Bank Creek and the Two Medicine River both originate along the east side of the east-west continental divide in Glacier Nation Park and flow in generally east directions onto the Montana plains, where Cut Bank Creek eventually turns to flow in a south-southeast direction to join the Two Medicine River and to form the east-oriented Marias River, which eventually joins the Missouri River. Topographic map evidence shows a complex pattern of multiple through valleys crossing the present day Cut Bank Creek-Two Medicine River drainage divide and intermediate drainage divides between Cut Bank Creek and Two Medicine River tributaries not only on the plains, but also in the high mountains near headwaters of the two east-oriented drainage routes. The through valleys are interpreted to have been eroded as anastomosing flood flow channels formed during massive south- and southeast-oriented melt water floods which flowed across the region. Flood waters are interpreted to have been derived from a rapidly melting thick North American ice sheet, which had been located in a deep “hole.” The deep “hole” was created by a combination of deep glacial erosion and of crustal warping, which uplifted the Rocky Mountains as immense melt water floods flowed across them. South and southeast oriented melt water floods were flowing along the present day east-west continental divide as the deep Two Medicine River valley eroded headward into the Glacier National Park region. Subsequently headward erosion of the deep Cut Bank Creek valley beheaded south-oriented flood flow channels to the newly eroded Two Medicine River valley. A combination of crustal warping and headward erosion of deep west-oriented valleys west of the present day continental divide subsequently created the continental divide. A diversion of the gigantic south-oriented melt water floods to the North Atlantic Ocean ended the thick ice sheet rapid melt down and changed climates so as to create a thin ice sheet on the former thick ice sheet floor while also enabling development of numerous alpine glaciers in the newly uplifted and flood eroded Rocky Mountains. The alpine glaciers further shaped valleys and mountain landforms in the Two Medicine River and Cut Bank Creek headwaters areas.

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 Cut Bank Creek-Two Medicine River drainage divide area landform origins in Glacier 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 by leaving a comment here with a link to those essays.
  • 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 Cut Bank Creek-Two Medicine River drainage divide area landform evidence in Glacier County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see link to paradigm related essay in menu at top of page). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Cut Bank Creek-Two Medicine River drainage divide area location map

Figure 1: Cut Bank Creek-Two Medicine 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 Cut Bank Creek-Two Medicine River drainage divide in Glacier County, Montana. Glacier County is located in northern Montana just east of Glacier National Park. The Canadian border is located directly north of Glacier County while the east-west continental divide is located in eastern Glacier National Park and defines the Glacier County western boundary (and the boundary between British Columbia to the west and Alberta to the east in Canada). Rivers of importance in this essay include the Missouri River, which can be seen in figure 1 southeast quadrant where it flows in a northeast direction from Great Falls to Fort Benton and Loma before turning the flow in a south-southeast direction to the figure 1 east edge (south of Big Sandy) with water eventually reaching the Gulf of Mexico (Atlantic Ocean). The Marias River is an east-southeast and south oriented tributary joining the Missouri River near Loma and is formed at the confluence of Cut Bank Creek and the Two Medicine River a short distance south of Cut Bank. Cut Bank Creek originates in eastern Glacier National Park and flows in an east-northeast direction to near Cut Bank and then turns to flow in a south-southeast direction to join the Two Medicine River. The Two Medicine River also originates in eastern Glacier National Park and flows in an east and north-northeast direction to join Cut Bank Creek south of Cut Bank, Montana. The Cut Bank Creek-Two Medicine River drainage divide area investigated in this essay includes the region from the Cut Bank Creek and Two Medicine River headwaters just east of the east-west continental divide to the Cut Bank Creek-Two Medicine River confluence area. West of the Cut Bank Creek and Two Medicine River headwaters is the Flathead River drainage basin, with water in the Flathead River eventually reaching the Columbia River and the Pacific Ocean. North of the Cut Bank Creek headwaters are headwaters of the Milk River which flows in a northeast direction into southern Alberta, with the Milk River eventually returning to Montana and joining the Missouri River in northeast Montana. The Milk River-Cut Bank Creek drainage divide area landform origins, Glacier County, Montana essay describes the region directly north of the Cut Bank Creek-Two Medicine River drainage divide area. Other regional essays can be found under the Marias River and Milk River categories (see sidebar category list).
  • Cut Bank Creek and the Two Medicine River both have headwaters in high mountains along the east-west continental divide and flow in eastward directions onto the Montana plains where they join to form the Marias River, which then joins the Missouri River. The Cut Bank Creek-Two Medicine River drainage divide area as seen in topographic map evidence illustrated in this essay was eroded by massive southeast and south oriented flood flow, which at one time or another crossed the entire drainage divide area, including the high mountains which today form the east-west continental divide. The flood waters were derived from a rapidly melting thick North American ice sheet, which had been located in a deep”hole.” The fact flood waters crossed high mountain ridges along the present day east-west continental divide suggests the Rocky Mountains in northern Montana and adjacent Alberta were the deep “hole’s” western rim. Probably at the time the ice sheet originally formed the Rocky Mountains did not stand high above the adjacent plains to the east, but instead the deep “hole” was created by a combination of deep glacial erosion and of flood water erosion and by crustal warping caused by the ice sheet’s great weight (and perhaps the removal of great thickness of bedrock cover by melt water flood erosion). Initially melt water floods flowed in south and southeast directions along the ice sheet’s west and southwest margin on routes which are today crests of high Rocky Mountain ranges and then in southeast and south directions along the east-west continental divide into Wyoming, Colorado, and New Mexico. At that time the Rocky Mountains were not the high mountain mountains as they are today and flood waters freely flowed along those routes, which today appear to be most unlikely of possible melt water flood flow routes. Rocky Mountain uplift proceeded from south to north and dismembered the southeast and south oriented flood flow routes in sequence from south to north. Flood waters were progressively diverted both to the east and west with major southeast-oriented river valleys such as the Rio Grande and Arkansas River valleys and southwest-oriented river valleys such as the Colorado River valley being eroded by the immense south-oriented melt water floods. How much of the elevation difference between the high Rocky Mountains and the adjacent plains to the east is due to deep flood water erosion of easily eroded bedrock material or due to crustal uplift as flood waters flowed across the region is difficult to determine as evidence strongly suggests uplift occurred as flood waters flowed across the region.
  • To set the stage for events illustrated in the following topographic maps the thick ice sheet, with its roots in the developing deep “hole”, initially stood high above the surrounding non glaciated continental regions and ice marginal melt water flood waters could easily flow from Alberta southward along the ice sheet margin. However in time the combination of ice sheet melting and of crustal warping, which was raising the Rocky Mountains, created a situation where the ice marginal melt water floods could no longer freely flow in south and southeast directions and the flood waters began to be turned in north and northeast directions toward the decaying ice sheet floor (the deep “hole” being opened up by ice sheet melting). At about that time huge supra glacial melt water river began to carve giant ice-walled canyons into the ice sheet surface and deep east and northeast oriented valleys eroded headward from these gigantic canyons to capture the ice marginal floods. Today the final versions of these east and northeast oriented drainage routes represent the upper Missouri River drainage basin in northern Wyoming and Montana. These east and northeast oriented valleys were eroded headward in sequence from south to north and from southeast to northwest. The Missouri River valley seen in figure 1 eroded headward from a deep and immense southeast and east oriented ice-walled and bedrock floored canyon which crossed present day Saskatchewan, North Dakota, and South Dakota (today the northeast- and east-facing Missouri Escarpment is what remains of the canyon’s southwest and west wall). The deep Missouri River valley and its tributary valleys captured both south and southeast oriented ice marginal flood flow trapped between the rising Rocky Mountain and the decaying ice sheet southwest margin and also south and southeast-oriented ice marginal flood flow which began by flowing between rising Canadian Rocky Mountain ranges into western Montana where the flood waters were then blocked in southwest Montana by rising mountains and diverted in north and northeast directions toward the evolving deep “hole” being opened up as the ice sheet melted. In the case of figure 1 the Missouri River tributary valleys seen were eroded in sequence from south to north as they captured south and southeast oriented flood flow. The Teton River valley eroded headward across the region before the Marias River valley headward erosion beheaded flood flow to newly eroded Teton River valley. Next Milk River valley headward erosion beheaded flood flow to the newly eroded Marias River valley. Headward erosion of the Saskatchewan River valley and its tributary valleys subsequently beheaded south and southeast oriented flood flow to the newly eroded Milk River valley. In the case of the Cut Bank Creek-Two Medicine River drainage divide the topographic map evidence illustrates Cut Bank Creek valley headward erosion beheaded south and southeast oriented flood flow to the newly eroded Two Medicine River valley along the entire drainage divide.

Detailed location map for Cut Bank Creek-Two Medicine River drainage divide area

Figure 2: Detailed location map for Cut Bank Creek-Two Medicine River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 2 illustrates a detailed location map for the Cut Bank Creek-Two Medicine River drainage divide area in Glacier County. The United States-Canada border is located along the figure 2 north edge. County boundaries and Glacier and Pondera Counties are labeled. East of Glacier County is Toole County and west of Glacier County is Flathead County. The Glacier and Pondera County west border is defined by the east-west continental divide, which except for a few deep mountain passes follows the crests of high mountain ridges. Drainage west of the continental divide is to the Flathead River with water eventually reaching the Pacific Ocean. Drainage to the east of the continental divide, except in the St Mary River drainage basin in the figure 2 northwest quadrant, flows to the Missouri River with water eventually reaching the Gulf of Mexico. The St Mary River (flowing from St Mary Lake) flows to the Oldman River which joins the South Saskatchewan River with water eventually reaching Hudson Bay. Different shading on figure 2 shows Glacier National Park, the Blackfeet Indian Reservation, and National Forest areas. Browning is a larger community located near the figure 2 center. East Glacier Park is located south and west of Browning. The Two Medicine River originates west of East Glacier Park near Lone Walker Mountain and flows through Two Medicine Lake and Lower Two Medicine Lake before reaching East Glacier Park. From East Glacier Park the Two Medicine River flows in a east-southeast, northeast, and east-southeast direction to join Cut Bank Creek on the Glacier County-Pondera County border (and to form the Marias River), south of the town of Cut Bank, which is located on the east edge of the Blackfeet Indian Reservation near the Glacier County eastern edge. Do not confuse the eastern Two Medicine River route with Spring Creek, which is a Cut Bank Creek tributary north of Two Medicine River. Irrigation canals shown on figure 2 suggest there are drainage links between Two Medicine River, Spring Creek, and Cut Bank Creek, and as we will see on topographic maps through valleys used by the irrigation canals strongly suggest such links once existed. The North Fork Cut Bank Creek originates west of Mad Wolf Mountain, just north of the Two Medicine River (North Fork) point of origin, and flows in a north and east-northeast direction to join the South Fork Cut Bank Creek (which originates south of Mad Wolf Mountain) at a point north and east of Browning. From the confluence of its North and South Forks Cut Bank Creek flows in an east and east-northeast direction before turning to flow in a south-southeast direction to join the Two Medicine River. Willow Creek is a labeled northeast, east, and northeast oriented Cut Bank Creek tributary from the south. Note how Cut Bank Creek has several south-southeast oriented tributaries from the north suggesting the Cut Bank Creek valley eroded headward across multiple south-southeast oriented flood flow channels such as might be found in a large south-southeast-oriented anastomosing channel complex.

North Fork Cut Bank Creek-Two Medicine Lake drainage divide area

Figure 3: North Fork Cut Bank Creek-Two Medicine Lake drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 3 illustrates the North Fork Cut Bank Creek-Two Medicine Lake drainage divide area adjacent to the east-west continental divide. The east-west continental divide is labeled and serves as the Glacier-Flathead County border, which is also labeled. Nyack Creek is the north and northwest oriented stream west of the continental divide and is a tributary to the Flathead River, which eventually flows in a south direction to join northwest-oriented Clark Fork, which eventually reaches the Columbia River. The Two Medicine River begins at Upper Two Medicine Lake (near figure 3 south edge, west of center) and flows in an east-northeast direction to Two Medicine Lake and then to Lower Two Medicine Lake where it turns to flow in a southeast direction to the figure 2 southeast corner. The Dry Fork Two Medicine River originates at Oldman Lake and flows in an east and southeast direction to join the Two Medicine River between Two Medicine Lake and Lower Two Medicine Lake. The North Fork Cut Bank Creek originates at Pitamakan Lake (just north of Oldman Lake) and flows in a north and northeast direction to the figure 3 north edge (just east of center). Lake Creek originates at Running Crane Lake (east of the north-oriented North Fork Cut Bank Creek segment) and flows in an east, northeast, southeast, and east direction to the figure 3 east edge (just north of center). At first glance the figure 3 map area looks like a region where alpine glaciers have played a significant role in shaping the topographic features. Valley heads in many cases are cirques, valley walls appear to have been steepened by valley glaciers, and the lakes appear to have glacial origins. While the glacial features are significant and indicate the region has been glaciated by alpine glaciers, the valleys existed before the alpine glaciation and it is the valley origins we must start with. The valleys were eroded by immense south and southeast oriented melt water floods from the rapidly melting thick North American ice sheet prior to the alpine glaciation, which later further shaped the figure 3 landscape. Evidence for the south and southeast oriented flood flow is found in the form of present day through valleys crossing drainage divides. For example between Pitamakan Lake and Oldman Lake there is a mountain pass (or through valley) which was eroded by south-oriented flood flow moving to what was then the actively eroding Dry Fork Two Medicine River valley prior to headward erosion of the North Fork Cut Bank Creek valley. Headward erosion of the North Fork Cut Bank Creek valley beheaded the south-oriented flood flow channel to the newly eroded Dry Fork Two Medicine River valley and flood waters on the north end of the beheaded flood flow route reversed flow direction to erode the north-oriented North Fork Cut Bank Creek valley. Headward erosion of the north-oriented North Fork Cut Bank Creek valley segment may have been aided by southeast-oriented flood flow from west of the present day continental divide prior to headward erosion of the southwest-oriented Nyack Creek valley segment (west of figure 3), which beheaded southeast-oriented flood flow routes to erode the northwest-oriented Nyack Creek valley segment as seen in figure 3.
  • The question may be asked how did the alpine glaciation develop after the rapidly melting thick North American ice sheet had ceased to melt rapidly? Initially melt water floods from the rapidly melting thick North American ice sheet flowed in south and southeast directions to the Gulf Of Mexico (with some flood waters also flowing in south and southwest directions to the Pacific Ocean), although a significant per cent of the melt water went to the Gulf of Mexico. The inflow of massive quantities of melt water into the Gulf of Mexico displaced warm Gulf of Mexico water forcing it into the Atlantic Ocean where it was moved northward by ocean currents and warmed the northern hemisphere climate. This northern hemisphere climate warming was causing the thick ice sheet to melt faster and faster. In time gigantic south-oriented ice-walled and bedrock-floored canyons were carved into the decaying ice sheet floor by immense south-oriented melt water rivers. But even later northeast and north oriented ice-walled and bedrock-floored canyons began to be carved as melt water flowed across the ice sheet surface in those directions as well. Eventually the northeast and north oriented ice-walled and bedrock-floored canyons began to intersect the south-oriented ice-walled and bedrock-floored canyons and the huge south-oriented melt water rivers were gradually captured and diverted to flow on the much higher gradient northeast and north oriented canyon routes. Diversion of the immense south-oriented flood waters from the Gulf of Mexico to the North Atlantic Ocean and to other northern regions significantly changed ocean currents. Instead of warm water being pushed north, cold northern waters were pushed south and the northern hemisphere climate changed. What had been an ever warming climatic pattern shifted to an ever cooling climate pattern, which in time caused what were then immense north-oriented melt water floods to freeze on the decaying ice sheet floor and to form what was for all practical purposes a new thin ice sheet, with isolated segments of the former thick ice sheet embedded within it. At the same time the climatic conditions were ideal for development of alpine glaciers in the newly uplifted and deeply eroded (by the south-oriented melt water floods) Rocky Mountains, which now stood high above the surrounding region. Over time the thin ice sheet gradually melted, without any immense melt water floods such as the thick ice sheet had created. Also over time many of the alpine glaciers melted to leave landscapes as seen in figure 3.

Detailed map of Pitamakan Lake-Oldman Lake drainage divide area

Figure 4: Detailed map of Pitamakan Lake-Oldman Lake 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 Pitamakan Lake-Oldman Lake drainage divide area seen in less detail in figure 3 above. Again this region shows remarkable alpine glacial features, which altered the previously existing valley system. However, it is important to remember there were water eroded valleys prior to the alpine glaciation and those water eroded valleys were carved by massive south and southeast oriented flood flow derived from the rapidly melting thick North American ice sheet at a time when flood waters were flowing along what is now the east-west continental divide. Figure 4 illustrates a number of mountain passes (some labeled some not) or through valleys crossing what are now major drainage divides. Pitamakan Pass is a through valley crossing the drainage divide between north-oriented North Fork Cut Bank Creek valley and the east-oriented Dry Fork Two Medicine River valley. The map contour interval is 50 feet and the elevation at Pitamakan Pass is between 7550 and 7600 feet. Mount Morgan to the west rises to 8781 feet while to the east there are peaks with elevations of 8193, 8528, and even 9377 feet. Depending on which points are chosen the Pitamakan Pass through valley may have been a south-oriented flood water eroded valley of 600 feet to 1100 feet or more in depth before headward erosion of the deep east- and northeast-oriented North Fork Cut Bank Creek valley eroded headward to behead and reverse the south-oriented flood flow. Where did the water come from that eroded the deep North Fork Cut Bank Creek valley? Look at Cut Bank Pass between Mount Morgan and McClintock Peak. Southeast-oriented flood flow from northwest of figure 4 flowed across Cut Bank Pass first into the south-oriented flood flow channel to the newly eroded Dry Fork Two Medicine River valley, but later when the flood flow channel was beheaded and reversed to flow in a north direction the southeast-oriented flood flow was captured by the actively eroding North Fork Cut Bank Creek valley. The elevation at Cut Bank Pass appears to be between 7750 and 8000 feet, which again depending on which high points along the continental divide one uses means the southeast-oriented flood flow channel was at least 300 feet deep and may have been much deeper. The southeast-oriented flood flow channel was subsequently beheaded by headward erosion of west-oriented Nyack Creek tributary valleys in sequence from south to north. Probably the west-oriented Nyack Creek tributary valleys eroded headward at a time when what is today the northwest-oriented Nyack Creek valley was still a southeast-oriented flood flow channel draining to the actively eroding Two Medicine River valley south of figures 4 and 3. As previously mentioned headward erosion of the southwest-oriented Nyack Creek valley segment (west of figures 4 and 3 and not shown) beheaded the southeast-oriented flood channel and flood waters on the northwest end of the beheaded flood flow channel reversed flow direction to erode the northwest-oriented Nyack Creek valley segment. Uplift of the mountains in figures 3 and 4 was probably occurring as flood waters were flowing across the region and probably further complicated the elevation difference seen today as did the subsequent alpine glaciation, which significantly modified the valleys to produce the present day landscape.

South Fork Cut Bank Creek-Two Medicine River drainage divide area

Figure 5: South Fork Cut Bank Creek-Two Medicine River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 5 illustrates the South Fork Cut Bank Creek-Two Medicine River drainage divide area east of the figure 3 map area and includes overlap areas with figure 3. Figure 3 also shows the transition from the high Rocky Mountains to the Montana plains. East Glacier Park is the town near the figure 5 south edge just west of center. The west edge of Browning can be seen along the figure 5 east edge just south of the northeast corner. Lower Two Medicine Lake is located south of Two Medicine Ridge in the figure 1 west half and the Two Medicine River flows in a southeast direction from the Lower Two Medicine Lake to East Glacier Park and the figure 5 south edge. The South Fork Cut Bank Creek flows in a northeast and southeast direction in the figure 5 northwest quadrant and then in a northeast direction to the figure 5 north edge (east of center). Elk Creek is a southeast-oriented Two Medicine River tributary located east of East Glacier Park. Willow Creek originates north of the Two Medicine River (north and west of East Glacier Park) and flows in an east-southeast, northeast, and east direction to the figure 5 east edge (near Browning) and eventually joins Cut Bank Creek. Depot Creek is a northeast-oriented Willow Creek tributary crossing the figure 5 east edge south of Browning. Flatiron Creek originates near the figure 5 center and flows in a north, northeast, east, and southeast direction to join Willow Creek near Browning in the figure 5 northeast corner. Study of the figure 5 map area reveals a number of through valleys crossing present day drainage divides. At the west end of Two Medicine Ridge a through valley links a north-northeast and east-northeast South Fork Cut Bank Creek tributary valley with the Lower Two Medicine Lake basin. The figure 5 map contour interval is 50 meters and the through valley elevation at the drainage divide is between 1750 and 1800 meters. Elevations on Two Medicine Ridge rise to more than 1900 meters and elevations to the west rise even higher meaning the through valley is at least 100 meters deep. The through valley was eroded by a south-oriented flood flow channel prior to headward erosion of the east-northeast oriented South Fork Cut Bank Creek tributary valley, which beheaded and reversed the south-oriented flood flow to erode the north-northeast valley segment. Note a north-south oriented through valley linking that tributary valley with the South Fork Cut Bank Creek valley just to the north, which was eroded by the south-oriented flood flow channel prior to headward erosion of the South Fork Cut Bank Creek valley. Further east through valleys can be seen linking the South Fork Cut Bank Creek valley with the Flatiron Creek valley and linking the Flatiron Creek valley with the Willow Creek valley. Figure 6 is a detailed topographic map of the Willow Creek-Two Medicine River drainage divide north and east of East Glacier Park to illustrate more subtle through valleys located in that region.

Detailed map of Willow Creek-Two Medicine River drainage divide area

Figure 6: Detailed map of Willow Creek-Two Medicine River 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 Willow Creek-Two Medicine River drainage divide area north and east of East Glacier Park, which was seen in less detail in figure 5 above. The Two Medicine River flows in a southeast direction across the figure 6 southwest corner. Willow Creek is labeled and flows in a southeast, northeast, and east direction in the figure 6 north half. Elk Creek originates in sections 4 and 5 and flows in a southeast direction to the figure 6 south edge (east half) and joins the Two Medicine River south of the figure 6 map area. Note how the Elk Creek valley in section 5 is linked to a southwest-oriented Two Medicine River tributary valley by through valleys in sections 5, 8, and 9. The through valleys are oriented in a southwest-northeast direction and continue in a northeast direction beyond the southeast-oriented Elk Creek valley. The railroad at the siding labeled Spotted Robe is located in a northeast-oriented Willow Creek tributary valley, which is linked by a through valley with the Elk Creek valley (and the Two Medicine River valley further to the southwest). This northeast-oriented valley eroded headward from what was at that time the actively eroding Willow Creek valley head, which was also about the same time that the Two Medicine River valley and the Elk Creek valley were eroding headward into the region. In other words all of the major stream valleys were competing with each other for flood flow moving across the figure 6 map area. For a time flood waters moved in a northeast direction toward the actively eroding Willow Creek valley head. Then headward erosion of the deep Two Medicine River valley beheaded and reversed the northeast-oriented flood flow channel to erode the southwest-oriented Two Medicine River tributary valley. Next Elk Creek valley headward erosion captured southeast-oriented flood between the northeast-oriented Willow Creek tributary and the southwest-oriented Two Medicine River tributary. Evidence of southeast-oriented flood flow to the actively eroding Elk Creek valley can be seen in the north-south oriented through valley in section 32 linking the Willow Creek valley with the Elk Creek valley. Headward erosion of the deep Willow Creek valley next beheaded the south-oriented flood flow channel to the newly eroded Elk Creek valley and flood waters on the north end of the beheaded flood flow channel reversed flow direction to erode what is now a north-oriented Willow Creek tributary valley. This history requires events to have been closely spaced and the various valleys to have been eroding headward into the figure 6 map area at approximately the same time, although in the sequence described.

Depot Creek-Two Medicine River drainage divide area

Figure 7: Depot Creek-Two Medicine River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 7 illustrates the Depot Creek-Two Medicine River drainage divide area located east of the figure 5 map area and includes overlap areas with figure 5. Browning is the town located near the figure 7 north edge (west of center). The Two Medicine River flows in an east-southeast, east-northeast, and northeast direction near the figure 7 south edge. Southeast-oriented Elk Creek joins the Two Medicine River near the figure 7 southwest corner and several southeast-oriented Two Medicine River tributaries can be seen in the Big Rock area east of Elk Creek. Big Nose Coulee is an east-northeast oriented Two Medicine River tributary in the figure 7 southeast quadrant. Willow Creek flows in a north-northeast direction across the figure 7 northwest corner region and then dips back down into figure 7 east of Browning before flowing to the figure 7 north center edge. Kittson Coulee is a north-northeast and northeast oriented Willow Creek tributary in the figure 7 northeast quadrant. Depot Creek originates in the figure 7 west center region and flows in a northeast direction to join Willow Creek just east of Browning. The Depot Creek-Two Medicine River drainage divide area in the figure 7 southwest quadrant appears to be covered with hummocky topography with small depressions, some filled with water to form small lakes and has the appearance of a glacial moraine region although better map detail is needed for further interpretation. A close look at the Depot Creek-Two Medicine River drainage divide does reveal several shallow north-south oriented through valleys linking north-oriented Depot Creek headwaters and tributaries with south-oriented Two Medicine River tributaries. The through valleys were eroded by south-oriented flood flow prior to headward erosion of the northeast-oriented Depot Creek valley. Headward erosion of the northeast-oriented Depot Creek valley beheaded the south-oriented flood flow routes and flood waters on north ends of the beheaded flood flow channels reversed flow direction to erode north-oriented Depot Creek tributary and headwaters valleys. The through valleys are defined by a single 20-meter contour line and are not deep, but they exist and can be seen. Other shallow through valleys can be seen linking north- and northeast-oriented Depot Creek and Willow Creek tributaries with the Big Nose Coulee valley, which drains to the Two Medicine River. Shallow through valleys also cross the Willow Creek-Depot Creek drainage divide south and west of Browning and provide further evidence of southeast-oriented flood flow across the figure 7 map area prior to headward erosion of the Willow Creek valley.

Detailed map of Willow Creek-Depot Creek drainage divide area

Figure 8: Detailed map of Willow Creek-Depot 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 Willow Creek-Depot Creek drainage divide area seen in less detail in figure 7 above. Willow Creek flows in an east and northeast direction in the figure 8 northwest corner region. Depot Creek originates in section 36 and flows in an east, north-northeast, and northeast direction to the figure 8 northeast corner area. The southeast-oriented stream in section 1 is a Two Medicine River tributary. Note how the southeast-oriented Two Medicine River tributary valley is linked by an anastomosing maze of through valleys with a north-northeast oriented Willow Creek tributary valley and also with the Willow Creek valley. The hummocky topography seen in figure 7 on closer inspection appears to be formed by shallow flood eroded channels, perhaps into previously deposited flood transported sediments. The figure 8 map contour interval is 20 feet and the floor of the west-northwest to east-southeast oriented through valley in the north half of section 35 has an elevation at the Willow Creek-Two Medicine River drainage divide of 4967 feet (see spot elevation). The hill directly to the southwest (in section 35) rises to 5074 feet while the hills to the northeast rise even higher. In other words the through valley is more than 100 feet deep and is just one of several northwest to southeast oriented through valleys crossing the drainage divide between the north-northeast oriented Willow Creek tributary valley and the southeast-oriented Two Medicine River tributary valley. These multiple northwest-southeast oriented through valleys diverge and converge as would be expected in an anastomosing channel complex. Figure 8 also shows through valleys linking east-oriented Depot Creek tributary valleys with the Willow Creek valley (see section 25) and also linking the Depot Creek valley with the southeast-oriented Two Medicine River tributary valley. All of these through valleys were eroded by water and can best be explained in the context of massive southeast-oriented flood flow, which carved anastomosing channels into whatever material underlies this region and which then were systematically captured and diverted to the northeast by first headward erosion of the north-northeast oriented Depot Creek valley, second headward erosion of the north-northeast oriented Willow Creek tributary valley, and third headward erosion of the east-oriented Willow Creek valley seen near the figure 8 west edge. This sequence is consistent with the sequence seen in previous figures where south and southeast oriented flood flow was captured in sequence from south to north and from the southeast to the northwest.

Willow Creek-Two Medicine River drainage divide area

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

 

  • Figure 9 illustrates the Willow Creek-Two Medicine River drainage divide area east and slightly north of the figure 7 map area and includes overlap areas with figure 7. Willow Creek flows in an east, northeast, northwest, and east-northeast direction in the figure 9 northwest quadrant. Kittson Coulee is the northeast-oriented stream flowing to Kipp Lake near the figure 9 west center edge. The Two Medicine River flows in a northeast, east-southeast, and southwest direction in the figure 9 southeast quadrant and is joined by east-northeast oriented Badger Creek just south of the figure 9 southeast area and then flows in a southeast direction. Note Mission Lake in the figure 9 east center, which is drained by northeast-oriented Flat Coulee, which drains to Spring Creek (seen in figure 10), which then flows to the south-southeast oriented Cut Bank Creek segment east of figure 9. Note how the Two Medicine River valley is linked by multiple northeast-oriented through valleys with the Mission Lake and Spring Creek valley. The figure 9 map contour interval is 20 meters and the northeast-oriented through valleys are as much as 100 meters deep. These through valleys provide evidence of an anastomosing channel complex moving large volumes of flood water toward the south-southeast oriented Cut Bank Creek valley segment. Remember enough water was also flowing on the present day Two Medicine River alignment to enable that route to ultimately become the Two Medicine River route, which beheaded the northeast-oriented flood flow channels to the Mission Lake and Spring Creek valley. Guardipee Lake is located near the figure 9 center and just south of Guardipee Lake is a through valley linking the Willow Creek valley with the Mission Lake valley. Just west of that through valley is a hill with a spot elevation at the top of 1343 meters and south and west of that hill is another through valley. While subtle features compared to the much better defined Two Medicine River-Mission Lake through valleys these through valleys provide evidence of south and southeast oriented flood flow routes prior to headward erosion of the Willow Creek valley. The figure 9 evidence suggests the entire region was deeply eroded by south- and southeast-oriented flood waters as well as by headward erosion of deep northeast-oriented valleys (in sequence from the southeast to the northwest) which captured the southeast- and south-oriented flood water.

Spring Creek-Two Medicine River drainage divide area

Figure 10: Spring Creek-Two Medicine River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 10 illustrates the Spring Creek-Two Medicine River drainage divide area east of the figure 9 map area and includes overlap areas with figure 9. The town of Cut Bank is located just north of the figure 10 northeast corner. Cut Bank Creek flows in a south-southeast direction from the figure 10 north edge (near northeast corner) to the figure 10 east edge (south half). Flat Coulee drains in a northeast direction to east oriented Spring Creek in the figure 10 northwest quadrant and Spring Creek then flows to join Cut Bank Creek just south of the Cut Bank Municipal Airport. The Two Medicine River flows in a southeast direction (with some southwest jogs) in the figure 10 southwest corner area and is joined by east-northeast oriented Badger Creek near the southwest corner. After flowing for a distance south of the figure 10 south edge the Two Medicine River turns to flow into the figure 10 map area (east of center) before turning again to flow south of figure 10 map area and then joins Cut Bank Creek east of the figure 10 southeast corner to form the Marias River. Note how south of the Municipal Airport there is a north-oriented Spring Creek tributary, which is linked by a shallow through valley with a southeast and south oriented Two Medicine River tributary. Also note how headwaters of that southeast oriented Two Medicine River tributary are linked by another and higher level through valley with a northeast-oriented Spring Creek tributary valley. South of Squaw Buttes in the figure 10 south center region there is another high level through valley crossing the Spring Creek-Two Medicine River drainage divide. Similar subtle through valleys can be seen along the drainage divide further to the west and also along other figure 10 drainage divides. While subtle on the figure 10 map these through valleys show up much better on more detailed topographic maps and are water eroded features. The through valleys provide evidence of anastomosing flood flow channels which existed at the time the present day deep valleys were being eroded headward. Flood flow movements across the figure 10 map area were complex and I will not try to decipher all of the details. However, southeast and south oriented oriented flood flow channels were being captured by headward erosion of east- and northeast-oriented valleys from what was then the actively eroding south-southeast oriented Cut Bank Creek valley. Headward erosion of the deep Two Medicine River valley captured the south- and southeast-oriented flood flow first with headward erosion of the Spring Creek valley and its tributary valleys capturing the flood flow next. For a time flood waters from the west was flowing to both the actively eroding Two Medicine River valley and the actively eroding Spring Creek valley. Headward erosion of the east-oriented Cut Bank Creek valley segment (north of figure 10-see figures 1 and 2) next captured the south- and southeast-oriented flood flow while Two Medicine River valley headward erosion beheaded northeast-oriented flood flow channels to the actively eroding Spring Creek valley.

Additional information and sources of maps studied

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

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