Battle Creek-Savoy Creek drainage divide area landform origins, Blaine County, Montana, USA

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Battle Creek-Savoy Creek drainage divide area in Blaine County, Montana. Battle Creek originates in the Cypress Hills area of southwest Saskatchewan and flows in a south-southeast direction to join the east and southeast oriented Milk River in Montana. Savoy Creek originates in Montana along the south side of an upland surface east of the Battle Creek valley and flows in a southeast direction to join the Milk River. North of the Savoy Creek headwaters the Montana upland surface is drained by east and south-oriented Woody Island Coulee, with water eventually reaching the Milk River. Evidence for a large abandoned east and/or northeast-oriented headcut is located at the Woody Island Coulee headwaters, which is located near the Montana upland surface west edge. The rim of this abandoned headcut rises as much as 150 meters above the adjacent upland surface and more than 300 meters above the Battle Creek valley floor to the west and 350 meters above the Milk River valley floor to the south. The abandoned headcut is interpreted to have been eroded by east and/or northeast-oriented meltwater flood flow moving toward a deep ice-walled and ice-floored canyon carved into the surface of a decaying North American ice sheet. The much deeper Milk River and Battle Creek valleys are interpreted to have been eroded during a later phase of ice sheet’s melt down history as deep valleys eroded headward from a giant ice-walled and bedrock-floored canyon that developed as the ice sheet melted. Headward erosion of these final deep valleys captured immense southeast- and east-oriented ice-marginal melt water floods, some of which were flowing across erosion surfaces formed during earlier ice sheet melt down phases.

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 Battle Creek-Savoy Creek drainage divide area landform origins in Blaine 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 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 Battle Creek-Savoy Creek drainage divide area landform evidence in Blaine County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see 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.

Battle Creek-Savoy Creek drainage divide area location map

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

Figure 1 provides a location map for the Battle Creek-Savoy Creek drainage divide area and illustrates a region in extreme north central Montana with southwest Saskatchewan and the Alberta southeast corner north of the international border. The Missouri River flows in a northeast direction from the figure 1 west edge (just north of southwest corner) to Fort Benton and Loma before turning to flow in a southeast and east-northeast direction around the south side of the Bears Paw Mountain and then flowing in an east-southeast and east-northeast direction to Fort Peck Dam. The Milk River flows in a southeast direction from the figure 1 west edge (just north of the international border) to Havre, Montana and then flows in an east and east-southeast direction to Harlem and Malta, before making a jog to the north-northeast and then flowing in a southeast direction to join the Missouri River just downstream from Fort Peck Dam. Battle Creek is a south-southeast oriented Milk River tributary originating in the Cypress Hills region near the Saskatchewan southwest corner and joining the Milk River near Chinook, Montana. Lodge Creek is a southeast-oriented Milk River tributary immediately west of Battle Creek. The unnamed southwest and southeast-oriented stream east of Battle Creek and joining the Milk River near Harlem, Montana is Thirtymile Creek. Savoy Creek is not shown on figure 1, but is a southeast-oriented stream located east of Thirtymile Creek. North of the Thirtymile Creek headwaters is east-northeast, east, and south oriented Woody Island Coulee, which drains to southeast-oriented Cottonwood Creek, which flows to the north-northeast oriented Milk River segment. The Woody Island Coulee-Milk River drainage divide area landform origins essay describes the region immediately to the east and northeast of the Battle Creek-Savoy Creek drainage divide study region investigated in this essay. Milk River essays are listed under Milk River on the sidebar category list.

Evidence presented in this essay demonstrates headward erosion of a deep Milk River valley captured immense south and/or southeast-oriented floods as it eroded across the figure 1 map area. The south and/or southeast-oriented flood waters appear to have been preceded by northeast and/or east-oriented flood waters, which were flowing on the high level topographic surface into which the 200-meter plus deep Milk River valley was eroded. The flood waters were derived from a rapidly melting thick North American ice sheet, which had been located in a deep “hole” and were in reality ice-marginal melt water floods, which in a much bigger picture view had been flowing in a southeast direction along the decaying ice sheet’s southwest margin. The reason flood waters were moving in east and northeast directions in the Battle Creek and Woody Island Coulee area was the southeast-oriented ice-marginal floods had been captured by deep northeast and east-oriented valleys which had eroded headward from deep ice-walled and ice-floored canyons which had been carved into the melting ice sheet’s surface. Because the ice sheet was located in a deep “hole” the ice marginal flood waters were flowing on a topographic surface much higher in elevation than the floors of those deep ice-walled canyons and tributary valleys eroded headward from those deep ice-walled canyons across the ice sheet margin to capture the southeast-oriented ice-marginal flood waters. Evidence for the northeast-oriented flood flow is much better illustrated in the Woody Island Coulee-Milk River drainage divide area essay than in this essay, because Milk River and tributary valley headward erosion occurred during a later melt water flood erosion phase and destroyed much of the previous erosion phase evidence. The deep Milk River valley eroded headward from the deep Missouri River valley, which eroded headward from an ice-walled and bedrock-floored canyon located north and east of the figure 1 map area. The Missouri Escarpment is today all that remains of that giant southeast-oriented ice-walled and bedrock-floored canyon’s southwest wall.

Prior to becoming a bedrock-floored canyon that giant canyon had been an ice-walled and ice-floored canyon with the canyon floor elevation gradually being lowered as the ice sheet melted and as melt water floods lowered bedrock surfaces surrounding the ice sheet. The ice sheet had originally formed on a topographic surface now preserved by the highest level Rocky Mountain erosion surface, if the surface has been preserved at all. The deep “hole” in which the ice sheet had been located evolved by a combination of deep glacial erosion and of crustal warping caused by the ice sheet’s tremendous weight. Rocky Mountain uplift, including uplift of Rocky Mountain outlier ranges such as the Bears Paw Mountains and Little Rocky Mountains seen in figure 1, occurred as melt water floods flowed across the region and may have been aided by deep melt water flood erosion and deposition. The hundreds of essays in this Missouri River drainage basin landform origins research project are systematically illustrating how all valleys and drainage divides in the present day Missouri River drainage basin evolved as gigantic ice-marginal melt water floods eroded the deep “hole’s” southwest wall. In the case of the figure 1 map area prior to Milk River and tributary valley headward erosion flood waters probably flowed in an east and/or northeast direction across the Cypress Hills region to reach the deep southeast-oriented ice-walled canyon and as the canyon floor was lowered the flood water river route to the ice-walled canyon floor migrated eastward to the position of Wood Mountain. Next the route to the ice-walled canyon migrated slightly south and east to cross the Flaxville upland in northeast Montana (east of figure 1). Finally the route migrated east and south to the Montana northeast corner and North Dakota northwest corner as the ice-walled canyon became an bedrock-floored canyon, and began to erode into the ice sheet’s floor. The present day figure 1 drainage system was formed during the final downcutting phase, but it is important to remember the region was deeply eroded during each of several preceding erosion phases as well. As we will see the final erosion phase eroded large valleys more than 200 meters deep in the figure 1 map area and significantly lowered elevations throughout much of the entire figure 1 map area.

Detailed location map for Battle Creek-Savoy Creek drainage divide area

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

Figure 2 provides a more detailed location map for the Battle Creek-Savoy Creek drainage divide area and illustrates much of northern Blaine County, Montana. The Canadian border is located near the figure 2 north edge and the Blaine County borders south of the Canadian line are clearly shown. The Milk River flows in an east direction from the figure 2 west edge (south half) to Lohman, Chinook, North Fork, and Zurich before turning to flow in an east-southeast direction to Harlem, Savoy, and Dodson, which is located near the figure 2 southeast corner. Battle Creek flows in a south-southeast direction from the Blaine County northwest corner to join the Milk River near Chinook. A major Battle Creek tributary is northwest and southwest oriented East Fork Battle Creek. Note how East Fork Battle Creek has in addition to its northwest-oriented headwaters other northwest-oriented tributaries and some south-oriented tributaries with southeast-oriented tributaries. Also note how drainage routes east of East Fork Battle Creek flow in east and northeast directions to east-oriented Woody Island Coulee, which east of the figure 2 map area turns to drain in a south direction to southeast-oriented Cottonwood Creek, which in turn flows to the Milk River. While not apparent from the figure 2 map the east-oriented Woody Island Coulee drainage system is located on a much higher level topographic surface than most areas drained by the southeast-oriented Milk River tributaries. This east-oriented drainage basin is a relic of flood flow directions prior to headward erosion of the deep Milk River valley and its tributary valleys into the figure 2 map area. Milk River tributaries east of Battle Creek include southwest and southeast oriented Thirtymile Creek, which has a southwest-oriented East Branch. East of Thirtymile Creek is southeast-oriented Wayne Creek, with its West and East Forks and east of Wayne Creek is south-southeast oriented Savoy Creek. East of Savoy Creek is southeast-oriented Dodson Creek. Note how north of the Dodson Creek headwaters are several northeast-oriented streams, including Black Coulee. These closely spaced and roughly parallel northeast-oriented drainage routes are tributaries to southeast-oriented Cottonwood Creek and are eroded into a higher level surface than the Dodson Creek and Savoy Creek drainage basins and provide evidence of flood flow directions prior to headward erosion of the deep Milk River valley (west of Dodson). Topographic maps illustrated in the following figures better illustrate how the deep Milk River valley and its deep southeast-oriented tributary valleys deeply eroded much of the figure 2 map area. Most flood waters reaching the actively eroding Milk River valley from the north and west were generally moving in a southeast direction with the greatest concentration of southeast-oriented flood flow moving along the alignment of south-southeast oriented Battle Creek, although there was some southwest-oriented flood flow along the southwest and south margins of the upland region east of the south-southeast oriented Battle Creek valley and north of the shorter southeast-oriented Milk River tributaries.

Forgey Creek-Savoy Creek drainage divide area

Figure 3: Forgey Creek-Savoy Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 illustrates the Forgey Creek-Savoy Creek drainage divide area. The Milk River flows in a southeast direction across the figure 3 southwest corner and is located in a large southeast-oriented valley. Harlem, Montana is the town located in the Milk River valley near the figure 3 southwest corner. Thirtymile Creek is the southeast-oriented Milk River tributary flowing through Harlem. East of Thirtymile Creek is southeast-oriented Forgey Creek, which flows from the figure 3 northwest corner to the figure 3 south center edge and which joins the Milk River south of the figure 3 map area. Wayne Creek is the southeast-oriented stream with several southeast and south-southeast oriented tributaries located east of Forgey Creek and Savoy Creek is the southeast and south-southeast oriented stream east of Wayne Creek and is joined by west-southwest and southwest oriented Black Creek in the figure 3 east center region. Note the east-southeast and south oriented Black Creek tributary in the figure 3 northeast quadrant. The west-southwest oriented Black Creek headwaters valley is linked to northeast-oriented tributary valleys to southeast-oriented Cottonwood Creek (not seen in figure 3). Wayne Creek and Savoy Creek both join the Milk River south of the figure 3 map area. Note elevations of various areas in the figure 3 map region. The map contour interval is 20 meters and elevations near the figure 3 northeast corner rise to more than 940 meters. Spot elevations on the Milk River valley floor south of Harlem read in 710-720 meter range and where Savoy Creek joins the Milk River (south of the figure 3 map area) there is a spot elevation of 704 meters. These spot elevations indicate the Milk River valley floor is at least 230 meters lower than the upland surface seen in the figure 3 northeast corner. With the exception of west-southwest and southwest oriented Black Creek (a Savoy Creek tributary) the Milk River tributaries seen in figure 3 all are oriented in southeast directions indicating southeast-oriented flood flow played a significant role in eroding those tributary valleys. While not much of the 900 meter plus high upland surface is visible in figure 3 it is possible to see a northeast-oriented valley near the figure 3 northeast corner. The upland surface generally shows evidence of a different drainage pattern, which was created by flood flow before headward erosion of the deep Milk River valley and its southeast-oriented tributary valleys into the figure 3 map area. The upland surface will be better seen in figure 4.

East Branch Thirtymile Creek-Wayne Creek drainage divide area

Figure 4: East Branch Thirtymile Creek-Wayne Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 illustrates the East Branch Thirtymile Creek-Wayne Creek drainage divide area north and west of the figure 3 map area and includes overlap areas with figure 3. Middle Butte is the labeled high area in the figure 4 northwest quadrant where elevations rise to more than 1060 meters. Thirtymile Creek originates as a west-oriented stream just north of the Middle Butte west end and then turns to flow in south-southwest and south direction to the figure 4 west center area before turning to flow in a south and south-southeast direction to the figure 4 south edge (west half). South of figure 4 Thirtymile Creek flows to the Milk River. The Northwest Fork Thirtymile Creek flows in a southwest direction across the figure 4 northwest corner and after flowing west of the figure 4 map area turns to flow in a southeast direction to join Thirtymile Creek in the figure 4 west center area. The East Branch Thirtymile Creek flows in a south-southwest direction from Snider Spring at the east end of the Middle Butte upland to join Thirtymile Creek in the figure 4 southwest quadrant. East and south of the south-southwest oriented East Branch Thirtymile Creek are headwaters of several southeast-oriented Milk River tributaries. From west to east the labeled southeast-oriented Milk River tributaries are West Forgey Creek, South Fork and West Fork (Wayne Creek), Wayne Creek, and West Savoy Creek (with south-southwest oriented East Savoy Creek located in the figure 4 southeast corner). What has happened here is headward erosion of the south-southwest oriented East Branch Thirtymile Creek valley has beheaded multiple southeast-oriented flood flow channels moving to what were once actively eroding southeast-oriented Milk River tributary valleys. Note how elevations in the Thirtymile Creek valley seen in the figure 4 southwest quadrant are less than 800 meters and as seen in figure 3 where Thirtymile Creek joins the Milk River are less than 720 meters. Also note how elevations rise in a northeast direction toward Middle Butte and also toward a less well-drained upland plain in the figure 4 northeast region (which is not quite as high as Middle Butte, but which still has elevations greater than 950 meters over much of the figure 4 northeast quadrant). The southwest-facing valley wall seen in the figure 4 southwest two-thirds is in reality the wall of the large south-southeast oriented Battle Creek valley, which eroded headward from the deep Milk River valley. The Savoy Creek, Wayne Creek, Forgey Creek, and Thirtymile Creek valleys were eroded by flood waters moving to the actively eroding Milk River valley head when that deep valley head eroded headward to the south of the figure 4 map area and drained flood waters into the newly eroded Milk River valley and deeply eroded the newly eroded Milk River valley north wall to produce the southwest-facing valley wall seen today in figure 4.

East Fork Battle Creek-Woody Island Coulee drainage divide area

Figure 5: East Fork Battle Creek-Woody Island Coulee drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the East Fork Battle Creek-Woody Island Coulee drainage divide area north and west of the figure 4 map area and includes overlap areas with figure 4. Middle Butte is the labeled high area in the figure 5 south center region and as seen in figure 5 forms the south rim of an east and northeast-oriented amphitheater shaped basin drained by east and northeast-oriented Woody Island Coulee, which is labeled in the figure 5 northeast quadrant. Other labeled high areas along the rim of amphitheater-shaped basin are West Butte and Cherry Ridge. Elevations along the rim of this east and northeast-oriented amphitheater-shaped basin are generally greater than 1060 meters with elevations decreasing in all directions, although the elevation decrease is much more rapid and greatest in a southwest direction. The Northwest Fork Thirtymile is labeled and flows in a southwest and south-southeast direction in the figure 5 southwest quadrant from the region between West Butte and Middle Butte to the figure 5 south edge (west half) and south of the figure 5 map area joins Thirtymile Creek, which then flows to the Milk River. Originating between Cherry Ridge and West Butte is west, southwest, and west oriented Chouteau Coulee, which west of the figure 5 map area drains to south-southeast oriented Battle Creek. Originating north of Cherry Ridge and flowing in a northwest direction are the headwaters of the East Fork Battle Creek. The east and northeast-oriented amphitheater shaped basin is what is left of an abandoned headcut which was eroded by immense east and northeast-oriented melt water floods moving across the figure 5 map area prior to the erosion phase in which the deep Milk River valley and its tributary valleys were eroded. At that time there was no deep Battle Creek valley to the west of the figure 5 map area and there was no deep Milk River valley south of the figure 5 map area. Elevations throughout the entire region were at least as high as the tops of Cherry Ridge, West Butte, and Middle Butte and the southwest margin of the decaying ice sheet was located east and north of the figure 5 map area. Immense southeast-oriented melt water floods were captured by headward erosion of deep east and/or northeast oriented valleys which eroded headward from an ice-walled and ice-floored canyon located on the decaying ice sheet’s surface (located north and east of figure 5). The northeast-oriented Woody Island Coulee valley segment is probably a relic of that flood flow movement. Headward erosion of southeast-oriented Milk River tributary valleys east of the figure 5 map area then began to capture the northeast-oriented flood flow, while headward erosion of the deep Milk River valley and Battle Creek valleys south and west of the figure 5 map area subsequently cut off all flood flow from the southwest and west and also surrounded the upland surface with deep valleys east and northeast of the abandoned headcut on at least three sides (to the north is the east and southeast-oriented Frenchman River valley in Saskatchewan, which is another Milk River tributary). The northwest-oriented East Fork Battle Creek valley segment was eroded by a reversal of flood flow on the northwest end of a southeast-oriented flood flow channel beheaded by headward erosion of the southwest-oriented East Fork Battle Creek valley segment, which is seen in figure 6 below.

Battle Creek-East Fork Battle Creek drainage divide area

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

Figure 6 illustrates the Battle Creek-East Fork Battle Creek drainage divide area west of the figure 5 map area and includes overlap areas with figure 5 (the Canadian border is just north of figure 6). Battle Creek flows in a south direction near the north half of the figure 6 west edge and then turns to flow in a south-southeast direction to the figure 6 south edge (west half). The East Fork Battle Creek flows in a southwest and south-southwest direction from the figure 6 northeast quadrant to join Battle Creek near the figure 6 south edge. The northwest oriented East Fork Battle Creek headwaters segment can be seen near the figure 6 east edge (north half). Corral Coulee is a northwest and west-oriented East Fork Battle Creek tributary from the east. Note other northwest and west oriented East Fork Battle Creek tributaries from the east. The northwest-oriented tributary valleys were eroded by reversals of flood flow on northwest ends of southeast oriented flood flow routes beheaded by headward erosion of the south-southwest and southwest oriented East Fork Battle Creek valley. In the region between Battle Creek and the East Fork Battle Creek note the predominance of southeast oriented drainage routes, which flow to south-oriented East Fork Battle Creek tributaries. These southeast-oriented drainage routes are relics of southeast-oriented flood flow routes, which once flowed across the region to what was then the newly eroded and deep southwest-oriented East Fork Battle Creek valley. At that time the Battle Creek valley to the west had not been eroded and flood waters flowed freely to the actively eroding East Fork Battle Creek valley. This southeast- and south-oriented flood flow movement was responsible for eroding the landscape between Battle Creek and the East Fork Battle Creek. Elevations between Battle Creek and the East Fork Battle Creek are in the 810 meter range in the south and rise to slightly more than 860 meters in the north. Compare those elevations with the 1060 meter high elevations seen along the rim of the abandoned headcut seen in the figure 5 to the east. The figure 6 map area is located on the floor of what is a large southeast-oriented valley draining to the large Milk River valley. This large southeast-oriented valley, which was more than 200 meters deep when eroded, was eroded by southeast-oriented flood flow moving around the west end of the Cypress Hills to reach the deep east and southeast-oriented Milk River valley. The Cypress Hills upland and the west end of the east-oriented Frenchman River valley to the north of the figure 5 map area protected the upland region in figure 5 (and in areas east of figure 5) from the full brunt of the southeast-oriented ice-marginal melt water flood erosion.

Chouteau Coulee-Thirtymile Creek drainage divide area

Figure 7: Chouteau Coulee-Thirtymile Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Chouteau Coulee-Thirtymile Creek drainage divide area south and slightly east of the figure 6 map area and includes overlap areas with figure 6. Battle Creek flows in a south-southeast direction from the figure 7 west edge (north half) to the figure 7 south edge (west half). West Butte is located near the figure 7 northeast corner and Chouteau Coulee drains in a west, south-southwest, west, and southwest direction from north of West Butte to join Battle Creek east of North Chinook Reservoir near the figure 7 west center edge. South of Chouteau Coulee in the figure 7 west half is south-oriented Dry Fork Battle Creek, which joins Battle Creek south of the figure 7 map area. The unnamed south-southeast, south-southwest, and southeast oriented stream flowing to the figure 7 south center edge is Coal Creek, which south of the figure 7 map area flows directly to the Milk River. East of Coal Creek along the figure 7 south edge is Tule Lake and east of Tule Lake is southeast and south-oriented Fifteenmile Creek. East of Fifteenmile Creek is the Northwest Fork Thirtymile Creek, which flows in a southwest direction from the south side of West Butte and then turns to flow in south-southeast direction to join south-southwest and south oriented Thirtymile Creek near the figure 7 southeast corner. Note the range of elevations in the figure 7 map area. West Butte in the figure 7 northeast corner area rises to more than 1060 meters. The Battle Creek valley floor near the figure 7 west edge has an elevation of less than 800 meters (the North Chinook Reservoir normal pool level is marked as 786 meters). These elevations indicate the Battle Creek valley was almost 300 meters deep as it eroded headward into the upland surface now represented by high elevations in the West Butte region. Headward erosion of the Chouteau Coulee valley from the Battle Creek valley beheaded south- and southeast-oriented flood flow moving to what were then the actively eroding Dry Fork Battle Creek and Fifteenmile Creek valleys. Shallow through valleys can be seen linking the Fifteenmile Creek valley with the Chouteau Coulee valley. Figure 8 below provides a detailed topographic map to better illustrate the through valleys.

Detailed map Chouteau Coulee-Fifteenmile Creek drainage divide area

Figure 8: Detailed map Chouteau Coulee-Fifteenmile 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 Chouteau Coulee-Fifteenmile Creek drainage divide area seen in less detail in figure 7 above. Chouteau Coulee is labeled and drains from the figure 8 northeast corner area in a west direction in the figure 8 northern region. Fifteenmile Creek is also labeled and drains in a south-southwest and south direction from the figure 8 northeast corner region to the figure 8 south edge (east half). Note the northwest-southeast oriented through valleys linking the Chouteau Coulee valley with the Fifteenmile Creek valley. One through valley is located in the section 11 and 12 region located in the figure 8 northeast quadrant and has a floor elevation of between 2800 and 2810 feet (the map contour interval is ten feet). The streamlined hill in the northwest quadrant of section 14 rises to 2845 feet and the high point near the south edge of section 10 is marked as having an elevation of 2851 feet. Elevations greater than 2900 feet can be seen in the figure 8 northeast corner (the highest elevation on West Butte, which is north and east of figure 8, is marked as 3559 feet). In other words the section 11 and 12 valley is at least 40 feet deep and probably was deeper when eroded. A somewhat narrower and more streamlined through valley crosses section 15 and has a floor elevation of between 2760 and 2770 feet. As already noted the streamlined hill to the northeast has a high point of 2851 feet while elevations greater than 2840 feet can be found to the southwest. This streamlined through valley is at least 70 feet deep. The northwest-southeast oriented through valleys provide evidence of multiple southeast-oriented flood flow channels which once moved flood water to the actively eroding Fifteenmile Creek valley. The southeast-oriented flood flow was beheaded by headward erosion of the west-oriented Chouteau Coulee valley. Another northwest-southeast oriented through valley can be seen in the figure 8 southeast quadrant (near the east edge) and links the south-southwest oriented Fifteenmile Creek valley with the south-southwest oriented Northwest Fork Thirtymile Creek valley (not seen in figure 8). The through valley floor elevation is between 2790 and 2800 feet and elevations to the southwest rise to more than 2830 feet while to the northeast elevations rise even more. This through valley provides evidence that headward erosion of the south-southwest oriented Fifteenmile Creek valley beheaded southeast-oriented flood flow moving to what was once the actively eroding Northwest Fork Thirtymile Creek valley.

Battle Creek-Fifteenmile Creek drainage divide area

Figure 9: Battle Creek-Fifteenmile Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Battle Creek-Fifteenmile Creek drainage divide area south of the figure 7 map area and includes overlap areas with figure 7. Chinook is the town near the figure 9 southwest corner and is located in the large east-southeast oriented Milk River valley. North Fork and Zurich are smaller towns located east of Chinook. The Milk River meanders across the figure 9 south edge in the figure 9 south center edge area, but is mostly located south of the figure 9 map area. Battle Creek flows in a south-southeast direction from the figure 9 west edge (north half) to the figure 9 south edge (near North Fork). The Dry Fork Battle Creek flows in a south direction from the figure 9 north edge (just east of northwest corner) to join Battle Creek near the figure 9 west center edge. Coal Creek flows in a south-southeast, southwest, and south-southeast direction from the figure 9 north edge (west of center) to join the Milk River just east of North Fork. Fifteenmile Creek flows in a south-southeast direction from the figure 9 east edge (north half). Thirtymile Creek can be seen along the figure 9 east edge, and then turns to flow in a southeast direction to join the Milk River south and east of the figure 9 map area. Note how Dry Fork Battle Creek has several labeled tributaries in the figure 9 northwest quadrant. These labeled Dry Fork Battle Creek tributaries include Deadhorse Coulee, Coyote Coulee, and Boxelder Coulee. These Dry Fork Battle Creek tributaries are located in what appears to be a maze of valleys with the Dry Fork Battle Creek making a jog to the northeast to meet southwest-oriented Deadhorse Coulee before resuming its south-oriented flow. Also note shallow through valleys linking the southwest-oriented Deadhorse Coulee valley with southwest-oriented Coyote Coulee valley and also linking the Coyote Coulee valley with the Coal Creek valley. The southeast-oriented through valleys were eroded by southeast-oriented flood flow as the southwest-facing Battle Creek northeast wall was being shaped prior to headward erosion of the southwest-oriented Coyote and Deadhorse Coulee valleys. Those valleys were eroded by southwest-oriented flood flow moving down the newly eroded northeast-oriented Battle Creek valley wall. These through valleys are better seen on more detailed topographic maps and figure 10 below illustrates the Coyote Coulee-Coal Creek drainage divide area to better illustrate the through valley there.

Detailed map of Coyote Coulee-Coal Creek drainage divide area

Figure 10: Detailed map of Coyote Coulee-Coal Creek drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 10 provides a detailed topographic map of the Coyote Coulee-Coal Creek drainage divide area seen in less detail in figure 9 above. Coyote Coulee is labeled and is located in the figure 10 northwest quadrant and drains to south-oriented Dry Fork Battle Creek in section 14 along the figure 10 west edge. Note how Coyote Coulee has a significant southeast-oriented tributary, which north of the figure 10 map area is linked by a through valley with the southwest-oriented Deadhorse Coulee valley. Also note the short northwest-oriented Coyote Coulee tributary valleys from the south. Boxelder Coulee is the west and southwest oriented “Coulee” located in sections 19 and 24 near the figure 10 south edge. Coal Creek is labeled as both Coal Creek and Coal Coulee and is located in the figure 10 east half. In the figure 10 northeast quadrant Coal Creek drains in a south-southeast direction and then turns in section 16 to flow in a south-southwest direction to section 20, where it joins a southeast-oriented valley to flow to the figure 10 south edge (near the southeast corner). Note how the southeast-oriented valley Coal Creek joins is linked by a through valley in section 20 with a west-oriented Coyote Creek tributary valley. The map contour interval is ten feet and the through valley floor elevation is between 2650 and 2660 feet. Elevations in the section 19 northwest quadrant rise to more than 2690 feet and elevation to the northeast of the through valley rise much higher. The northwest-southeast oriented through valley is eroded into the face of the southwest-facing slope and is a relic of southeast-oriented flood flow responsible for eroding the much larger Battle Creek valley. At the time the through valley was eroded the deep Battle Creek valley was also being eroded and flood waters along the east edge of the southeast-oriented Battle Creek valley were still moving to the southeast-oriented Coal Creek valley, which had been eroded slightly in advance of the larger Battle Creek valley. Milk River tributary valleys were eroded in sequence from east to west as the actively eroding Milk River valley head eroded into what was then a high level topographic surface at least 200 meters higher than the present day Milk River valley floor. As the deep Battle Creek valley and its tributary valleys eroded headward flood waters began to flow in a southwest direction down the newly eroded southwest-facing slope. Headward erosion of the southwest-oriented Coyote Coulee valley and its west-oriented tributary valley then beheaded the southeast-oriented flood flow route to the southeast-oriented Coal Creek valley and diverted the southeast-oriented flood flow to the newly eroded south-oriented Dry Fork Battle 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.