Whitewater Creek-Frenchman River drainage divide area landform origins, northeast Phillips County, Montana, USA

· Frenchman River, Milk River, Montana
Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Whitewater Creek-Frenchman River (Creek) drainage divide area in northeast Phillips County, Montana, which is located directly south of the Canadian border. Whitewater Creek and the Frenchman River are southeast and south oriented tributaries originating in southern Saskatchewan and flowing to the southeast-oriented Milk River in Montana, with Whitewater Creek being west of the Frenchman River. Between Whitewater Creek and the Frenchman River is south-oriented Stinky Creek, which is another Milk River tributary. Frenchman River tributaries from the west are generally south-southeast oriented, closely spaced, and roughly parallel to each other and suggest the deep Frenchman River valley eroded headward across multiple south-southeast oriented flood flow channels, such as might be found in a large anastomosing channel complex. Stinky Creek headwaters are linked by through valleys with north-northwest oriented East Fork Whitewater Creek, which further north turns at an abrupt elbow of capture to flow in a south direction to White water Creek. This elbow of capture and through valleys associated with it provide evidence of a major south-southeast oriented flood flow channel beheaded by headward erosion of the south-oriented East Fork Whitewater Creek valley. The entire drainage divide area was deeply eroded as deep valleys eroded headward across and along the south-southeast oriented flood flow. Flood waters were derived from a rapidly melting North American ice sheet and were flowing along the decaying ice sheet’s southwest margin. The deep valleys were eroding headward from a breach through the detached ice sheet’s southwest margin to the floor of an ice-walled and bedrock-floored canyon which had been carved by supra glacial melt water river into the decaying ice sheet surface.

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 Whitewater Creek-Frenchman River (Creek) drainage divide area landform origins in northeast Phillips 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 leaving links 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 in 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 Whitewater Creek-Frenchman River (Creek) drainage divide area landform evidence in northeast Phillips County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see menu at top of page for a paradigm related essay). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

Whitewater Creek-Frenchman River drainage divide area location map

Figure 1: Whitewater Creek-Frenchman 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 Whitewater Creek-Frenchman River drainage divide area in northeast Phillips County, Montana and illustrates a region in north central Montana with southwest Saskatchewan north of the international border. The Missouri River flows from the figure 1 west edge (south half) to Fort Peck Reservoir and then flows in an east direction to the figure 1 east edge. The Milk River is located north of the Missouri River and flows from the figure 1 west edge near the international border to Fresno Reservoir, Havre, Harlem, and Malta before making a jog to the northeast and then flowing in a southeast direction to join the Missouri River a short distance downstream from Fort Peck Dam. The Frenchman River originates in the Cypress Hills region in the figure 1 northwest corner area and flows in an east and east-southeast direction to the west unit of Grasslands National Park before flowing in a south direction to join the Milk River a short distance north of Saco, Montana. Whitewater Creek originates just north of the international border and west of the Grasslands National Park West Unit and flows in a southeast direction to join the Milk River near Nelson Reservoir. The Whitewater Creek-Frenchman River drainage divide area investigated in this essay is located south of the international border, north of the Milk River, west of the Frenchman River and east of Whitewater Creek. A previous essay addressed Frenchman River-Rock Creek drainage divide area landform origins in the region directly east of the study region. Additional regional drainage divide area essays, including drainage divide areas south of the Milk River and drainage divide areas north of the international border, are listed under Milk River on the sidebar category list.
  • Based on topographic map evidence presented in this essay and in hundreds of similar Missouri River drainage basin drainage landform origins research project essays the Whitewater Creek-Frenchman River drainage divide area was eroded by massive southeast and south-oriented oriented glacial melt water floods, which flowed across the entire figure 1 map area. Flood waters were derived from a rapidly melting thick North American ice sheet and were flowing along the ice sheet’s southwest margin, which had been detached by a giant south and southeast oriented ice-walled and bedrock-floored canyon. The ice-walled and bedrock-floored canyon had been carved into the decaying ice sheet surface by an immense southeast and south oriented supra glacial melt water river, which emerged from the ice sheet margin in southeast South Dakota. The ice sheet had formed on a topographic surface now preserved, if it is preserved at all, on the highest level Rocky Mountain erosion surfaces and had formed a deep “hole” in the North American continent. The deep “hole” had been formed by deep glacial erosion (underneath the massive ice sheet) and by crustal warping caused by ice sheet’s great weight. Late during the ice sheet melt down history supra glacial rivers carved large ice-walled canyons into the decaying ice sheet’s surface and floors of these ice-walled canyons were significantly lower than elevations of ice marginal regions, especially in the figure 1 map area. While a massive northwest-southeast oriented ice barrier stood between the higher ice-marginal melt water floods in the figure 1 map area and the ice-walled and bedrock-floored canyon floor (to the northeast of the figure 1 map area) breaches through the decaying ice barrier did open up and deep northeast and east-oriented valleys eroded rapidly headward to capture the immense southeast-oriented ice-marginal floods. The Missouri River valley and its tributary valleys, including the Milk River, Frenchman River, and Whitewater Creek valleys (as seen in figure 1) eroded headward from an ice barrier breach near the Montana northeast corner and North Dakota northwest corner. At that time the valleys were much deeper than they appear today and the massive melt water floods significantly lowered the regional surface as the deep valleys eroded headward across the figure 1 map area.
  • Note: United States maps used in this essay use the name Frenchman Creek, although Canadian maps use the name Frenchman River. I am using the name Frenchman River on both sides of the international border to be consistent and because most of the Frenchman River drainage route is in Canada.

Detailed location map for Whitewater Creek-Frenchman River drainage divide area

Figure 2: Detailed location map for Whitewater Creek-Frenchman 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 Whitewater Creek-Frenchman River drainage divide area in northeast Phillips County, Montana. The west to east oriented international border is located directly north of the figure 2 map area. The western two-thirds of the figure 2 map area shows northern Phillips County, Montana with the eastern third showing a region in northwest Valley County and the county line is prominently shown. The Milk River flows in an east direction from Chinook in the figure 2 southwest corner to Malta and then flows in a north-northeast direction around the Hewitt Lake National Wildlife Refuge before turning to flow in a southeast direction to the figure 2 southeast corner. The Frenchman River flows from the figure 2 north edge (just west of the county line) in a south-southeast and south direction to join the Milk River near the county line (north of the town of Beaverton). The north-, northeast, and southeast-oriented stream flowing from the figure 2 south center edge (south of Bowdoin National Wildlife Refuge) and flowing to Saco and Beaverton before joining the Milk River near Hinsdale is Beaver Creek. The north-oriented tributary joining Beaver Creek at Beaverton is Larb Creek. Beaver Creek and Larb Creek are important to this essay because they drain north ends of large north-south oriented through valleys linking the Milk River valley with the Missouri River valley to the south. Note how the Larb Creek valley is located on the same alignment as the south-oriented Frenchman River. These north-oriented valleys were eroded by reversals of flood flow on north ends of south-oriented flood flow channels beheaded by Milk River valley headward erosion (which then captured the south-oriented flood flow). Whitewater Creek flows in a southeast direction from the figure 2 north edge (west half) to the town of Whitewater and then joins the Milk River a short distance downstream from Nelson Reservoir (a railroad line, now abandoned, follows Whitewater Creek from Whitewater to the Milk River). Note how Frenchman River tributaries from the west are almost all oriented in south-southeast directions, roughly parallel to the southeast-oriented Whitewater Creek valley. These south-southeast oriented tributaries suggest the Frenchman River valley eroded headward across multiple south-southeast oriented flood flow channels such as might be found in a south-southeast oriented anastomosing channel complex. Whitewater Creek tributaries show a more complicated pattern, although several are oriented in southeast directions while others are oriented in northwest directions. None of the tributaries are labeled in figure 2, but the south-oriented tributary joining Whitewater Creek at Whitewater is the East Fork Whitewater Creek, which begins as a northwest-oriented stream (flowing towards Pea Lake). Southeast of Pea Lake the East Fork  Whitewater River joins a large south-southeast oriented through valley in which Pea Lake is located and makes an abrupt turn to flow in a south-southwest and south direction to join Whitewater Creek. This remarkable elbow of capture will be illustrated and discussed in figures 6, 7, 8, and 9 below.

South end of Whitewater Creek-Frenchman River drainage divide area

Figure 3: South end of Whitewater Creek-Frenchman River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 3 provides a big picture topographic map of the south end of the Whitewater Creek-Frenchman River drainage divide area. Whitewater Creek flows in a south-southeast direction from the figure 3 northwest corner  to join the Milk River near the Cole Ponds State Fishing Area (near figure 3 south center edge). Whitewater Creek has south- and southwest-oriented tributaries from the east. The one tributary shown is near the figure 3 northwest corner is Lush Coulee and begins as south-oriented stream (not shown) linked by a through valley to the Whitewater Creek valley and drains in a south, southeast, and east direction to rejoin the Whitewater Creek valley near the figure 3 northwest corner. This diverging and converging channel is typical of flood formed anastomosing channel complexes and is evidence of south-southeast flood flow across the figure 3 map area. The Milk River flows in a south-southeast direction in the figure 3 southwest corner region and then flows for a distance along the figure 3 south edge before turning to flow in southeast direction south of the figure 3 southeast corner. The Frenchman River flows in south-southwest and south direction from the figure 3 northeast corner region to join the Milk River south of the figure 3 southeast corner. Note how the Frenchman River has some incised meanders that appear to be related to the south-southeast oriented tributary valleys from the west. These incised meanders may have developed as the deep Frenchman River valley eroded headward across and then for short distances along the multiple south-southeast oriented flood flow channels. The multiple closely spaced south-southeast oriented Frenchman River tributaries from the west are further evidence of massive south-southeast-oriented flood flow across the figure 3 map area. The south-southeast and south oriented stream flowing from the figure 3 north center edge to join the Milk River just east of the Cole Ponds State Fishing Area is Stinky Creek. Note how the south-oriented Stinky Creek segment has south-southeast oriented tributaries. The south-southeast oriented Stinky Creek valley segment and the south-southeast oriented Stinky Creek tributaries are evidence the Stinky Creek valley eroded headward across multiple south-southeast oriented flood flow routes. Headward erosion of the Frenchman River valley would have occurred slightly in advance of Stinky Creek valley headward erosion, which would have occurred slightly in advance of Whitewater Creek valley headward erosion.

Stinky Creek-Frenchman River drainage divide area

Figure 4: Stinky Creek-Frenchman River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

 
  • Figure 4 uses a somewhat less reduced size topographic map to illustrate the Stinky Creek-Frenchman River drainage divide area north of the figure 3 map area and including overlap areas with figure 3. The Frenchman River flows in a generally south direction near the figure 4 east edge. Note how the Frenchman River has several closely spaced and roughly parallel south-southeast oriented tributaries. The named tributaries from north to south are Bohner Coulee, Corral Coulee, Rattlesnake Coulee, Poplar Coulee, and Porcupine Coulee. Some of these coulees originate as south-oriented streams suggesting the south-southeast orientation of the downstream segments may occurred as headward erosion of the deep south-oriented Frenchman River valley  captured south-oriented flood flow. Stinky Creek flows in south-southwest direction from the figure 4 north edge (west of center) to the figure 4 west center region and then turns to flow in a south-southeast direction to the figure 4 south edge (west of center). From the east Stinky Creek is joined by south-southwest and south oriented East Fork while in the figure 4 northeast corner area the south end of a south and south-southeast oriented valley drains to Stinky Creek. This through valley is a link to the north-northwest oriented headwaters of the East Fork Whitewater Creek, which will be seen better in figure 6 below. Note how the East Fork Stinky Creek has south-southeast oriented tributaries from the west and has southwest and south-southwest oriented tributaries from the east that appear to have beheaded at least some flood flow routes to what were once the south-southeast oriented Frenchman River tributary valleys. Slightly north and east of the small town of Forks, near figure 4 west center edge, a through valley can be seen linking the Stinking Creek valley with the East Fork Stinky Creek valley. On figure 4 this through valley appears to be oriented in a west to east direction and is defined by a single 20 meter contour line. This through valley is much more evident on more detailed topographic (not shown) and the more detailed maps also show north-northwest to south-southeast oriented through valleys as well. The through valleys provide evidence the East Fork Stinky Creek valley and its south-southeast oriented tributary valleys were eroded prior to headward erosion of the Stinky Creek valley, which beheaded flood flow routes to the East Fork Stinky Creek valley and its tributary valleys. However, it is probable flood waters were flowing in all valleys at the same time, at least for a time. The sequence of events of is the Frenchman River valley and its tributary valleys were eroded slightly in advance of the East Fork Stinky Creek valley and its tributary valleys, which were eroded slightly in advance of the of headward erosion of the Stinky Creek valley and its tributary valleys.

Whitewater Creek-Stinky Creek drainage divide area

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

 

  • Figure 5 illustrates the Whitewater Creek-Stinky Creek drainage divide area south and west of the figure 4 map area and includes overlap areas with figures 3 and 4. The southeast-oriented stream in the figure 5 southwest corner is the Milk River. Whitewater Creek flows in a south-southeast direction from the figure 5 northwest corner to the figure 5 south edge (west of center). Whitewater Creek tributaries from the east and north begin generally as south-oriented drainage routes and then drain in south-southwest, southwest directions, or west directions. From north to south these tributaries include Coop Coulee, Gregory Coulee, Clark Coulee, Bell Coulee, Hymer Coulee. The change in orientation from south-oriented drainage routes to more of west oriented drainage routes probably occurred as headward erosion of the deep south-southwest oriented Whitewater Creek valley was capturing what was at that time generally south-oriented flood flow. The map contour interval is 20 meters and the Whitewater River is approximately 100 meters deep (using elevations on uplands on either side of the valley including an upland slightly west of figure 5). Note how the south-southwest facing Whitewater Creek valley wall has been eroded by the south-southeast and southwest oriented streams and what must have general overland flood flow moving into what was then the actively eroding and deep Whitewater Creek valley. To the east south-oriented Stinky Creek has several south-southeast oriented tributary valleys. The multiple closely spaced and roughly parallel south-southeast oriented tributaries provide evidence Stinky Creek valley headward erosion captured multiple south-southeast oriented flood flow routes. A through valley links headwaters of Ole Olson Coulee with the south-southwest oriented Bell Coulee headwaters valley. The through valley provides evidence Bell Coulee valley headward erosion from what was then the actively eroding Whitewater Creek valley beheaded the flood flow to the actively eroding Ole Olson Coulee valley. South-southeast oriented Frenchman River tributaries can be seen flowing to the figure 5 east edge. Again the figure 5 map evidence suggests headward erosion of the Frenchman River valley and its tributary valleys captured massive south-oriented flood flow in the region slightly in advance of headward erosion of the Stinky Creek valley and its tributary valleys, which captured the south-oriented flood flow slightly in advance of Whitewater Creek valley headward erosion.

East Fork Whitewater Creek-Stinky Creek drainage divide area

Figure 6: East Fork Whitewater Creek-Stinky Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 6 illustrates the East Fork Whitewater Creek-Stinky Creek drainage divide area north of the figure 5 map area, north and west of the figure 4 map area, and includes overlap areas with figure 4. The town of Whitewater is located near the figure 6 southwest corner and Whitewater Creek flows in a south-southeast direction through Whitewater. The East Fork Whitewater Creek is the south-oriented stream joining Whitewater Creek at Whitewater and appears to be flowing from north of the figure 6 map area. However the East Fork Whitewater Creek flows in a west and north-northwest direction from Salsbery Reservoir almost to the figure 6 north edge and then turns to flow in a south direction to join south-southeast oriented Whitewater Creek. The East Fork Whitewater Creek elbow of capture was formed when headward erosion of the south-oriented East Fork Whitewater Creek valley beheaded a south-southeast oriented flood flow channel supplying flood water to the actively eroding Stinky Creek valley. Stinky Creek headwaters are located in the valley extending south from section 31 just south and west of Salsbery Reservoir and are linked by well-defined through valleys with the west and north-northwest oriented East Fork Whitewater Creek headwaters valley. Stinky Creek flows in a south direction from the Salsbery Reservoir area to the figure 6 south center edge near the small town of Forks. Figure 7 below illustrates a detailed map of the East Fork Whitewater Creek-Stinky Creek drainage divide area to better show the through valleys. Figures 8 and 9 illustrates the region north of the East Fork Whitewater Creek elbow of capture to illustrate a south-southeast oriented through valley, which at one time was eroded by the south-southeast oriented flood flow channel captured, beheaded, and reversed by headward erosion of the south-oriented East Fork Whitewater Creek valley.Other through valleys seen in figure 6 provide evidence of south-oriented anastomosing flood flow channels as the deep East Fork Whitewater Creek valley eroded headward across the region. Note the rim of the East Fork Whitewater Creek valley east of the town Whitewater and see how between Tea Kettle Butte and the valley rim there is a north-south oriented through valley. Both north and south along the East Fork Whitewater Creek valley rim are several other similar through valleys providing evidence of what were once multiple south-oriented flood flow channels, which were captured and consolidated into the much deeper East Fork Whitewater Creek valley.

Detailed map of East Fork Whitewater Creek-Stinky Creek drainage divide area

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

 

  • Figure 7 provides a detailed topographic map of the East Fork Whitewater Creek-Stinky Creek drainage divide area near Salsbery Reservoir. The East Fork Whitewater Creek flows in a west-southwest direction from the figure 7 northeast corner region to Salsbery Reservoir and flows in a west and northwest direction to the figure 7 north edge (west half). Stinky Creek originates near the figure 7 center and flows in a south direction to the figure 7 south edge. Note how a well-defined through valley links the Stinky Creek headwaters with the East Fork Whitewater Creek valley. The map contour interval is 20 feet and the through valley floor elevation is between 2780 and 2800 feet. Hills to the east rise to more than 2900 feet while west of the through valley hills in figure 7 rise even higher. A somewhat less well-defined through valley in the east half of section 31 links the Salsbery Reservoir area with the Stinky Creek valley. Perhaps an even more interesting through valley extends in a south-southwest direction from Schmittou Reservoir (west of Salsbery Reservoir) and then turns in a south-southeast direction to eventually join the Stinky Creek valley south of the figure 7 map area. West of the figure 7 map area additional though valleys can be found linking the north-northwest oriented East Fork Whitewater Creek valley with the south-oriented Stinking Creek valley. These through valleys have higher floor elevations than the through valley linking the Stinking Creek headwaters valley with the East Fork Whitewater Creek, which apparently represented the final south-oriented flood flow channel before headward erosion of the south-oriented East Fork Whitewater Creek valley beheaded and reversed the south-oriented flood flow so as to erode the north-northwest oriented East Fork Whitewater Creek valley. While difficult to interpret from the figure 7 map evidence alone it is possible flood waters were flowing in a region where ice sheet remnants were still present on what are today upland surfaces. Reasons for this suggestion are the hummocky topography observed on detailed topographic maps (not shown) of upland regions west of the figure 7 map area and the difference between the flood flow channels in this region and the closely spaced and parallel flood flow channels captured by Frenchman River valley headward erosion.

Haukos Coulee-East Fork Whitewater Creek drainage divide area

Figure 8: Haukos Coulee-East Fork Whitewater Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 8 illustrates the Haukos Coulee-East Whitewater Creek drainage divide area north of the figure 6 map area and includes overlap areas with figure 6. The international border is located at the top of the figure 8 map area. The East Fork Whitewater Creek flows in a northeast direction from the figure 8 southeast corner to the section 31 area where it turns to flow in a south-southwest and south direction to the figure 8 south edge (east half). As seen previously East Fork Whitewater Creek continues to flow in a south direction south of the figure 8 map area to join south-southeast oriented Whitewater Creek. Gustin Coulee is a southeast-oriented tributary to the East Fork Whitewater Creek in the figure 8 south center region. Northwest of the East Fork Whitewater Creek elbow of capture is Pea Lake and Haukos Coulee drains in a south-southwest direction into Pea Lake. Pea Lake is located on the floor of what is today a well-defined through valley extending from north of the international border to Pea Lake and then to the East Fork Whitewater Creek elbow of capture. The map contour interval is 20 meters and the south-sloping valley floor about one mile south of the international crosses the 760 meter contour line. Hills on either side rise gradually to elevations greater than 840 meters and enclose a broad south-southeast oriented valley, which once served as a major flood flow channel which as seen in figures 6 and 7 supplied flood water to what was once the actively eroding Stinky Creek valley and its tributary valleys. Headward erosion of the south-oriented East ForK Whitewater Creek valley from what was then the actively eroding southeast oriented Whitewater Creek valley captured the south-southeast oriented flood flow and diverted the flood water to the newly eroded Whitewater Creek valley. At the same time flood waters on the north-northwest end of the beheaded flood flow channel reversed flow direction to erode the north-northwest oriented East Fork Whitewater Creek valley segment.

Detailed map of Haukos Coulee-East Fork Whitewater Creek drainage divide area

Figure 9: Detailed map of Haukos Coulee-East Fork Whitewater Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 9 uses a more detailed topographic map to better illustrate the through valley linking Pea Lake and Haukos Coulee with the East Fork Whitewater Creek elbow of capture. The East Fork Whitewater Creek flows in a northwest and south-southwest direction in the figure 9 southeast quadrant. Pea Lake is located west of the figure 9 center and Haukos Coulee drains from the figure 9 north edge in a south direction to Pea Lake. No modern-day drainage route is shown linking Pea Lake with the East Fork Whitewater Creek, although a well-defined southeast-oriented valley links the two. Spot elevations on the through valley floor range from 2454 feet to 2468 feet while spot elevations on hills on either side rise to more than 2680 feet. This is a significant through valley which once carried significant south-southeast oriented flood flow to the present day East Fork Whitewater Creek elbow of capture. The northwest-oriented East Fork Whitewater Creek inner valley is much narrower suggesting at the end the flood water was turning at the elbow of capture to flow in a south-southwest and south direction with the northwest-oriented East Fork Whitewater Creek inner valley being eroded by the reversed flood flow moving in a northwest direction. Gravel pits appear to be present just west of where the southeast-oriented through valley joins the south-southwest oriented East Fork Whitewater Creek valley and may be evidence of flood water deposition on the inside of what became a major flood flow channel bend. Further information on the composition of materials present on the inside of that channel bend would be interesting and useful. As mentioned previously the hummocky landscape in the uplands between the valleys and the different nature of the valley patterns in this region compared with the closely spaced and roughly parallel tributary valleys draining to the Frenchman River suggest flood waters may have been flowing over a landscape still partially covered with ice. If so the valleys were first being carved into the ice surface and then into the underlying bedrock and became ice-walled and bedrock-floored valleys. As  the ice walls receded the wall were altered by flood flow and as the ice melted it deposited on uplands whatever debris it contained. Information on the nature of the ground material would be useful in confirming this suggestion.

East Fork Whitewater Creek-Frenchman River drainage divide area

Figure 10: East Fork Whitewater Creek-Frenchman River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 10 illustrates the East Fork Whitewater Creek-Frenchman River drainage divide area east of the figure 8 map area and includes overlap areas with figure 8. The East Fork Whitewater Creek flows in a northwest direction from Salsbery Reservoir to the figure 10 west center edge. Headwaters of the East Fork Whitewater Creek flow in a west-southwest direction to Salsbery Reservoir from the figure 10 south center region. Dunlap Coulee is a south-southwest and west oriented tributary to East Fork Whitewater Creek. The Frenchman River flows in a south-southeast direction from the figure 10 north edge (east half) to the figure 10 southeast corner and has eroded a deep valley. Tributaries from the west are generally oriented in southeast and/or south-southeast directions, closely spaced, and roughly parallel to the Frenchman River valley. These tributaries from north to south include Kennedy Coulee, Sand Creek, Dead Horse Coulee, and Cottonwood Creek. Note how Cottonwood Creek headwaters are oriented in a south-southwest direction and are linked by a shallow through valley with an east-oriented Kennedy Coulee tributary valley. The through valley provides evidence of what was once a diverging and converging flood flow channel beheaded by headward erosion of the much deeper Frenchman River valley. The Thoeny Hills are an interesting feature located between this former diverging and converging flood flow channel and the much deeper Frenchman River valley. Elevations in the Thoeny Hills rise to more than 940 meters and represent the highest points in the Whitewater Creek-Frenchman River drainage divide area. Elevations of upland regions to the west and south as seen in earlier figures are generally 100 or meters lower. The Thoeny Hills are probably an erosional remnant of an earlier topographic surface on which the flood waters originally flowed. If so that topographic surface probably extended across the entire the region and was lowered elsewhere as flood waters crossed the region. As noted previously the rapidly melting ice sheet was located in a deep “hole” and this Whitewater Creek-Frenchman River drainage divide was located on the southwest margin of that deep “hole”. As the ice sheet surface was lowered, ice marginal melt water floods also lowered the ice sheet margin regions. What we are seeing here is evidence of the depth of erosion that occurred when a breach through the detached ice sheet southwest margin (near the Montana northeast corner and North Dakota northwest corner) caused the deep Missouri River-Milk River valley to erode headward into the region and permitted south, south-southeast, southeast oriented melt water floods to lower the landscape as flood waters flowed to those new and deep east-oriented valleys draining onto what was then the newly exposed and lower elevation ice sheet floor.

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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