Cottonwood Creek-Sage Creek drainage divide area landform origins, Liberty and Hill Counties, Montana, USA

· Marias River, Milk River, Montana
Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Cottonwood Creek-Sage Creek drainage divide area located in Liberty and Hill Counties, Montana. Cottonwood Creek is a south oriented Marias River tributary with the Marias River flowing to the Missouri River, which flows across north central Montana on a route south of the Bears Paw Mountains. Sage Creek originates at East Butte in the Sweet Grass Hills north of the Cottonwood Creek headwaters and flows in a southeast direction to join northeast-oriented Big Sandy Creek with water flowing west and north of the Bears Paw Mountains to the east and southeast-oriented Milk River, which eventually joins the Missouri River. The Cottonwood Creek-Sage Creek drainage divide area was deeply eroded by massive south- and southeast-oriented melt water flood flow from a rapidly melting thick North American ice sheet, which had been located in a deep “hole”, with the present day landscape features being formed during final stages of the ice sheet’s rapid melt down history. Headward erosion of the deep Missouri River-Marias River valley and tributary valleys (including the Cottonwood Creek valley) and of the Milk River-Big Sandy Creek valley (including tributary valleys such as the Sage Creek valley and its tributary valleys) competed to capture the immense south-oriented melt water floods in the Cottonwood Creek-Sage Creek drainage divide area while flood waters flowing into these new deep valleys significantly lowered the regional drainage divide areas. Evidence for deep melt water flood erosion includes through valleys crossing modern drainage divides, streamlined erosional residuals, channels suggestive of former anastomosing channel complexes, and asymmetric drainage divides. Illustrated evidence documents many tens of meters of flood water erosion from much of the Cottonwood Creek-Sage Creek drainage divide area.

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 Cottonwood Creek-Sage Creek drainage divide area landform origins in Liberty and Hill Counties, 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 Cottonwood Creek-Sage Creek drainage divide area landform evidence in Liberty and Hill Counties, 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.

Cottonwood Creek-Sage Creek drainage divide area location map

Figure 1: Cottonwood Creek-Sage 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 Cottonwood Creek-Sage Creek drainage divide area in Liberty and Hill Counties, Montana and illustrates a region in north central Montana with the Saskatchewan southwest corner and Alberta southeast corner north of the United States-Canada border. The Missouri River flows in a northeast direction from the figure 1 south edge (west of center) to Fort Benton and Loma before turning to flow in a southeast and east-northeast direction around the Bears Paw Mountains south flank and then in an east-southeast direction to the figure 1 east edge (near southeast corner). The Milk River flows in an east direction across southern Alberta, just north of the international border, before turning in a southeast direction to flow to Havre, Montana. From Havre the Milk River flows in an east and east-southeast direction to the figure 1 east edge and east of figure 1 joins the Missouri River with water eventually reaching the Gulf of Mexico. Big Sandy Creek flows in a northeast direction along the Bears Paw Mountains western flank and joins the Milk River a short distance west of Havre. Sage Creek originates near East Butte (just south of the international border) and flows in a southeast direction to join Big Sandy Creek as a barbed tributary. The Marias River is formed by several tributaries south of Cut Bank, Montana (on highway 2 near figure 1 west edge) and flows in an east direction to Lake Elwell, which is a large reservoir impounded behind Tiber Dam. From Tiber Dam the Marias River flows in an east and south direction to join the Missouri River near Loma. Eagle Creek is a south oriented Marias River tributary flowing from near East Butte to Lake Elwell. Cottonwood Creek is not shown on figure 1, but is a south oriented stream east of Eagle Creek, which also originates near East Butte and which joins the Marias River just downstream from Tiber Dam. O’Brien Coulee is an east-oriented Sage Creek drainage route extending east from the Cottonwood Creek valley in the region between east-southeast oriented Little Sage Creek and highway 2 (between Chester and Gildford). The Cottonwood Creek-Sage Creek drainage divide area investigated in this essay is located east of Cottonwood Creek, west of Sage Creek, south of O’Brien Coulee, and north of the Marias River drainage basin. The Sage Creek-O’Brien Coulee drainage divide area landform origins essay discusses the region immediately to the north and the Sage Creek-Milk River drainage divide area landform origins essay describes the region directly to the east. The essays can be found by selecting Milk River from the sidebar category list.
  • Before looking specifically at the Cottonwood Creek-Sage Creek drainage divide area in Liberty and Hill Counties a brief summary of the big picture situation as determined from hundreds of Missouri River drainage basin landform origins research project essays is needed. The Cottonwood Creek-Sage Creek drainage divide area was eroded during the final stages of the rapid melt down of a thick North American ice sheet, which had been located in a deep “hole.” The ice sheet had been large, probably comparable in extent and thickness to the modern-day Antarctic Ice Sheet. The deep “hole” in which the ice sheet had been located was formed by a combination of deep glacial erosion and of crustal warping caused by the ice sheet’s great weight. The surface on which the ice sheet had originally formed is preserved today, if it preserved at all, on the highest level Rocky Mountain erosion surfaces, although those high-level Rocky Mountain erosion surfaces were probably uplifted by ice sheet caused crustal warping, at least some of which occurred as massive melt water floods flowed across the Rocky Mountain region. Initially the ice sheet stood high above the surrounding landscape and melt water floods flowed in south and southeast directions in whatever directions the regional topography permitted. Uplift of Rocky Mountain ranges in time began to block many melt water flood routes forcing melt water floods, which entered the Rocky Mountain region in Canada and then flowed in south directions between rising Canadian Rocky Mountain ranges to become trapped between rising mountain ranges in southwest Montana and to flow in north directions into north central Montana between rising Rocky Mountain ranges toward the ice sheet’s southwest margin. At the same time ice sheet melting gradually lowered the ice sheet surface so it no longer stood high above the surrounding region. In fact, a giant southeast and south-oriented supra-glacial melt water river carved an immense ice-walled canyon in the ice sheet surface. This huge ice-walled canyon became a major regional drainage route with major east and northeast oriented tributary valleys extending west and southwest of the ice sheet’s southwest margin and into the rising Rocky Mountain region of Montana and northern Wyoming. In time the large ice-walled canyon also became a bedrock-floored canyon and detached the decaying ice sheet’s southwest margin. Today the northeast and east-facing Missouri Escarpment in Saskatchewan, North Dakota, and South Dakota is what remains of this gigantic ice-walled and bedrock flooored canyon’s southwest and west wall.
  • How much bedrock material was removed from the figure 1 map area is difficult to determine, although some markers provide a few clues. The highest point on East Butte has an elevation of 2121 meters, which is more than 1000 meters higher than the surrounding region. Topographic map evidence reveals valleys between high East Butte peaks which probably were eroded by south and southeast-oriented melt water flood flow, although it is possible the East Butte peaks were being uplifted as flood waters flowed across the region. A spot elevation of 2103 meters is shown on figure 1 in the Bears Paw Mountains south of Havre. Again topographic map evidence shows multiple through valleys cross high Bears Paw Mountains areas, which probably were eroded by massive south and southeast-oriented melt water flood flow so there is evidence flood waters once flowed on a surface more than 1000 meters higher than the plains surrounding the East Butte and Bears Paw Mountains upland regions. The Cypress Hills straddle the Alberta-Saskatchewan border just north of the international border and are capped by a high-level erosion/deposition surface. Spot elevations of 1466 and 1392 meters are shown in figure 1, which are several hundred meters higher than the surrounding plains regions. The high-level Cypress Hills erosion/deposition surface probably was formed by an east or northeast oriented “ice-marginal” melt water flood river flowing onto the ice sheet surface and then to the large ice-walled canyon further to the northeast, which represent an erosion cycle prior to the erosion cycle responsible for present day figure 1 drainage routes, although there is evidence south oriented melt water floods also cross the Cypress Hills upland surfaces. Modern day figure 1 drainage routes were eroded very late during the decaying ice sheet’s rapid melt down when a deep east and northeast-oriented valley eroded headward from what was then the deep ice-walled and bedrock-floored canyon in northwest North Dakota. West of Poplar, Montana (not shown in figure 1) that large valley is today used by the Missouri River. Tributary valleys, including the Milk River valley, eroded headward from that large east and northeast-oriented valley to capture south- and southeast-oriented ice-marginal melt water floods moving along the  decaying ice sheet’s southwest margin and also to capture east, northeast-, and north-oriented melt water floods which had become trapped between rising Rocky Mountain ranges and which were seeking new and lower elevation routes on which to flow. As these massive melt water floods flowed toward the deep Missouri River valley and its deep tributary valleys the flood waters also deeply eroded drainage divide areas and gradually developed the drainage patterns and landscape features seen today.

Detailed location map for Cottonwood Creek-Sage Creek drainage divide area

Figure 2: Detailed location map for Cottonwood Creek-Sage Creek 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 Cottonwood Creek-Sage Creek drainage divide area in Liberty and Hill Counties, Montana. County boundaries and names are shown. Fresno Reservoir floods the southeast oriented Milk River valley and the Milk River flows in a southeast and east direction from Fresno Dam to Havre, Montana, which is the city located near the figure 2 east center edge. Big Sandy Creek flows in a north-northeast direction along the west side of the Rocky Boys Indian Reservation, which east and south of Big Sandy Creek is located in the Bears Paw Mountains area. East Butte is located just north and west of the figure 2 northwest corner and is not shown in figure 2. Sage Creek flows in a southeast direction from the figure 2 north edge (at Liberty-Hill County line) to join Big Sandy Creek a short distance north of the Hill County line. Little Sage Creek flows in an east-southeast direction from the figure 2 northwest corner to join Sage Creek in the figure 2 northwest quadrant. O’Brien Coulee is located midway between Little Sage Creek and the west to east oriented highway (and railroad line) and drains to Sage Creek somewhat north of the figure 2 center. Cottonwood Creek flows in a south and south-southeast direction from the figure 2 west edge (north half) to the figure 2 south edge (near southwest corner) and flows through the town of Chester. South of figure 2 Cottonwood Creek flows to the Marias River. Other figure 2 southwest quadrant drainage routes including southeast-oriented Black Coulee flow eventually to the Marias River. Further east are east oriented coulees, including Faulkner Coulee, draining to southeast-oriented Sage Creek. The region investigated in this essay is south of O’Brien Coulee, east of Cottonwood Creek, west of Sage Creek, and north of Faulkners Coulee. The study region was deeply eroded by immense southeast- and south-oriented melt water floods which were captured by headward erosion of the deep southeast-oriented Sage Creek valley and its east-oriented tributary valleys. Prior to capture by headward erosion of the Sage Creek and tributary valleys flood waters were probably moving to the what was then the deep Missouri-Marias River valley, which was probably eroding headward into the region (see figure 1). A puzzle to be explained is southeast-oriented flood waters appear to have been moving toward what are today the Bears Paw Mountains, which today form a significant topographic barrier. Flood flow routes suggest at least some flood waters flowed across the Bears Paw Mountains, which is difficult to explain unless the Bears Paw Mountains were being uplifted as flood waters flowed across the region. Evidence related to that problem including topographic illustrating high level flood eroded through valleys is presented and discussed in Big Sandy Creek-Beaver Creek drainage divide area landform origins and the Big Sandy Creek-Birch Creek drainage divide area landform origins essays.

O’Brien Coulee-England Coulee drainage divide area.

Figure 3: O’Brien Coulee-England Coulee drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 3 illustrates the O’Brien Coulee-England Coulee drainage divide area north of Rudyard and Hingham, Montana. Sage Creek flows in a south-southeast direction near the figure 3 east edge and then flows through Gildford, Montana, which is located near the highway just east of the figure 3 east edge. O’Brien Coulee drains in an east-southeast direction from the figure 3 north edge (near northwest corner) to join Sage Creek in the figure 3 northeast quadrant. Hingham Coulee drains in an east-southeast direction from the figure 3 west center edge to Hingham Lake (which is labeled). Note how Hingham Lake appears to have no outlet. The southeast oriented coulee originating near the town of Hingham is England Coulee, which joins Sage Creek south and east of the figure 3 map area. Compare elevations in the figure 3 map area (860-960 meters) with elevations of high points at East Butte to the north (2121 meters) and in the Bears Paw Mountains to the southeast (2103 meters) and note elevations in the figure 3 map area are at least 1100 meters lower than the highest regional elevations. As previously mentioned there is evidence flood waters crossed high elevations almost as high as the high points shown and a valid question is how were melt water floods able to do so. Four possibilities are worthy of consideration. First, the region was covered with at least 1100 meters of ice. Second, melt water floods removed at least 1100 meters of bedrock material from the entire region surrounding those high points. Third, the high points were uplifted during and after the melt water floods. And fourth, some combination of the previous three possibilities. While figure 3 appears to be a relatively low relief region there is evidence in figure 3 suggesting southeast-oriented melt water floods did deeply scour the region. North of Hingham Lake is a through valley linking the O’Brien Coulee valley with the England Coulee valley. East of Hingham Lake is a north-northwest to south-southeast oriented erosional residual defined by the 940 and 960 meter contour lines. West of the through valley elevations rise even higher to more than 980 meters along the figure 3 west edge and to more than 1000 meters west of the figure 3 map area. The through valley floor elevation is between 920 and 940 meters, which means the through valley is at least 20 meters deep. The Sage Creek valley floor east of the erosional residual has an elevation of between 860 and 880 meters, suggesting it was eroded even deeper. These valleys were eroded by southeast- and south-oriented melt water floods flowing across the figure 3 map area. While only a few tens of meters deep these valleys do demonstrate that flood waters did strip significant bedrock thicknesses from the figure 3 map area.

Detailed map of O’Brien Coulee-England Coulee drainage divide area

Figure 4: Detailed map of O’Brien Coulee-England Coulee drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 4 is a reduction of a detailed topographic map of the O’Brien Coulee-England Coulee drainage divide area seen in less detail in figure 3 above. O’Brien Coulee can be seen draining in an east direction near the north edge of the figure 4 northeast quadrant. Hingman Coulee drains in an east-southeast direction from the figure 4 west edge (south of center) to Hingham Lake in sections 23 and 26. England Coulee is located south and east of the figure 4 map area although a southeast-oriented through valley links the Hingham Lake basin with the England Coulee valley. Note how north of Hingham Lake there is a through valley in section 14 linking the Hingham Lake basin with the O’Brien Coulee valley. A second north-south oriented through valley of similar depth is found in section 13 just to the east. The first through valley floor elevation along what appears to be a narrow inner channel is between 3050 and 3060 feet, although much broader through valley floor areas are defined by the 3070 and higher contour lines (the figure 4 map contour interval is ten feet). A somewhat higher level and more subtle through valley can be seen in section 18 a short distance further to the east. This third through valley has a floor elevation of between 3110 and 3120 feet and is defined by two contour lines on the west. East of the through valleys is the streamlined erosional residual seen in figure 3 where elevations in sections 20 and 29 rise to more than 3180 feet. A close at the figure 4 map reveals additional subtle through valleys including one across the top of the streamlined erosional residual in section 20 (figure 4 southeast quadrant). This high level through valley has a valley floor elevation of 3160 to 3170 feet. Elevations a short distance west of the figure 4 southwest quadrant rise to more than 3300 feet suggesting the deeper through valleys were at least 120 feet deep and may have been much deeper. The south-southeast oriented Sage Creek valley east of the figure 4 map area is still deeper. The multiple through valleys with different valley floor elevation suggests multiple south-oriented flood flow channels such as might be formed in an anastomosing channel complex. Headward erosion of the deep south-southeast oriented Sage Creek valley east of the figure 4 map area and of its east-southeast oriented tributary valleys in sequence captured the south-oriented flood flow channels, with water being diverted to the newly eroded Sage Creek valley. The east-southeast oriented England Coulee-Hingham Coulee valley captured the south-oriented flood flow channels first with headward erosion of the east-southeast and east oriented O’Brien Coulee valley beheading south-oriented flood flow to the England Coulee-Hingham Coulee valley.

Cottonwood Creek-Hingham Coulee drainage divide area

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

 

  • Figure 6 illustrates the Cottonwood Creek-Hingham Coulee drainage divide area west of the figure 3 map area and includes overlap areas with figure 3. Cottonwood Creek flows in a south direction along the figure 5 west edge with the town of Chester just south of the figure 5 southwest corner. South of the figure 5 map area Cottonwood Creek flows to the Marias River. O’Brien Coulee originates in the figure 5 northwest quadrant and drains in an east, southeast, northeast, and east direction to the figure 5 east edge (near northeast corner). Hingham Coulee originates near the radio tower in the figure 5 east center area and drains in a southeast direction to the figure 5 east edge (south half). Renal Flat, just north of the figure 5 south center edge area, is drained by the southeast-oriented East Fork Black Coulee, which flows near the town of Joplin with water eventually reaching the Marias River. Note Adobe Ridge in the figure 5 west center region where elevations rise to more than 1100 meters (the map contour interval is 20 meters). Adobe Ridge is another streamlined erosional residual and provides a marker to document how much bedrock material has been stripped from the surrounding regions. West of Adobe Ridge is the Cottonwood Creek valley where elevations are less than 1000 meters. The Cottonwood Creek valley was eroded headward by massive south-oriented melt water floods which removed at least 100 meters of bedrock material from the valley area. East of Adobe Ridge is a somewhat more subtle through valley linking the O’Brien Coulee valley with East Fork Black Coulee valley (or Renal Flats area). This through valley is defined by a smaller erosional residual located north of Joplin and is defined by a single contour line (the 1040 meter contour line). The through valley is shallow, but it exists and at one time was a south-oriented melt water flood flow channel. Note also in the figure 5 northwest quadrant how the east-oriented O’Brien Coulee valley is linked by a through valley with the south-oriented Cottonwood Creek valley. This east-oriented through valley provides evidence that at one time flood waters flowed east along the O’Brien Coulee valley to Sage Creek while at the same time flood waters were flowing in a south direction in the actively eroding Cottonwood Creek valley. These through valleys define a complex of anastomosing channels such as might be formed by a massive flood crossing the figure 5 map region.

Detailed map of O’Brien Coulee-Renal Flat drainage divide area

Figure 6: Detailed map of O’Brien Coulee-Renal Flat drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 6 provides a detailed topographic map of the through valley linking O’Brien Coulee and Renal Flat seen in less detail in figure 5 above. O’Brien Coulee drains in an east direction north of the figure 6 map area. O’Brien Coulee as seen in figure 5 drains to Sage Creek, with water eventually reaching the Milk River. Renal Flat is an intermittent lake located south of the figure 6 map area on the line between sections 22 and 23 (section numbers are seen along figure 6 edge). As seen in figure 5 Renal Flat drains to the East Fork Black Coulee, with water eventually reaching the Marias River. The north-south oriented through valley linking the O’Brien Coulee valley with the East Fork Black Coulee valley is located in sections 10 and 11 near the figure 6 center. The figure 6 map contour interval is ten feet and the through valley floor elevation at its lowest point is between 3360 and 3370 feet. Elevations on the erosional residual on the line between sections 1 and 12 rise to more than 3440 feet. Elevations along the figure 6 west edge in section 8 rise to more than 3500 feet. The through valley is at least 70 feet deep and the regional slope to the east may be the result of deeper erosion in that direction. In other words south-oriented melt water floods scoured at least 70 feet of bedrock material from the section 10 and 11 area and probably were responsible for lower elevations across the entire figure 6 map area. The streamlined erosional residual in sections 1, 12, and 13 provides just a minimal marker to document that deep flood water erosion has occurred. Adobe Ridge, which is west of the figure 6 map area (see figure 5) is another similar and much higher streamlined erosional residual with a high point of 3636 feet. West of Adobe Ridge is the south-oriented Cottonwood Creek valley where elevations are less than 3300 feet. East of the figure 6 map area is south-southeast oriented Sage Creek valley where elevations are less than 2850 feet. Using these larger region markers it appears flood waters originally flowed on a surface at least as high as the top of Adobe Ridge and probably much higher. While elevations differ throughout the Cottonwood Creek-Sage Creek drainage divide area as seen in figure 6 (and in other figures in this essay) the Adobe Ridge elevation suggests much of the drainage divide area has been stripped of at least 200 feet of bedrock material with valley areas being eroded even deeper. Remember there is no evidence suggesting the Adobe Ridge upper surface represented the surface on which the melt water flood waters originally flowed. The possibility for much deeper melt water flood erosion of the entire figure 6 map area definitely exists.

Hingham Coulee-England Coulee drainage divide area

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

 

  • Figure 7 illustrates the Hingham Coulee-England Coulee drainage divide area south of the figure 3 map area and includes overlap areas with figure 3. Rudyard and Hingham are the towns in the figure 7 north half and Gildford is near the highway just east of the figure 7 map area. Sage Creek flows in a south-southeast direction across the figure 7 northeast corner. Hingham Coulee drains in a southeast direction to Hingham Lake (near the figure 7 north edge). England Coulee originates near the town of Hingham and drains in a southeast and east direction to the figure 7 east center edge. The East Fork Black Coulee drains in an east and southeast direction across the figure 7 southwest corner region. Again the figure 7 map area appears at first glance to show a low relief region, however on close inspection a shallow northwest to southeast oriented through valley can be found. The through valley was described in the figure 3 discussion and extends from Hingham Lake to the town of Hingham (and the area just south of Hingham) and links the Hingham Coulee valley with the England Coulee valley. Other less obvious through valleys can also be found. For example west of Rudyard and just south of the highway is a non streamlined erosional residual defined by the 980 meter contour line. On either side of that erosional residual are shallow valleys linking an east-oriented drainage route to the previously defined northwest-southeast oriented Hingham Coulee-England Coulee through valley with a south-oriented drainage route to the East Fork Black Coulee. Midway between Rudyard and Hingham and just south of the highway is a somewhat streamlined erosional residual defined by the 940 meter contour line. Shallow valleys on either side of this erosional residual define what were probably two different flood flow channels on the floor of the Hingham Coulee-England Coulee through valley. Each of these through valleys, and all of the other subtle through valleys in the figure 7 map area, appears to be relatively inconspicuous evidence. However, these valleys exist and were eroded by something, which based on evidence from adjacent regions was most likely massive southeast and south-oriented melt water flood flow. There are no obvious markers in the figure 7 map area to document how deep the region was eroded, although elevations near the figure 7 west center edge are more than 980 meters (probably approaching 1000 meters) while elevations near the figure 7 east center edge are less than 900 meters, which suggests more than 100 meters of bedrock material has been eroded from the figure 7 east edge region.

Detailed map of Hingham Coulee-England Coulee drainage divide area

Figure 8: Detailed map of Hingham Coulee-England Coulee drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 8 is a reduction of a detailed topographic map of the Hingham Coulee-England Coulee drainage divide area seen in less detail in figure 7 above. Rudyard is the town in the figure 8 west half while Hingham is the town in the figure 8 east half. England Coulee originates north of the town of Hingham and drains in a south-southeast direction and east direction to the figure 8 east edge (south half). Hingham Lake is located near the north edge of the figure 8 northwest quadrant. The figure 8 map contour interval is ten feet. Note how an east-southeast oriented through valley extends from Hingham Lake to the Hingham town location and then to the England Coulee valley. The map does not show a continuous drainage route in the through valley today, although obviously should Hingham Lake overflow the water would flow to England Coulee. The through valley floor just east of Hingham Lake has an elevation of between 3050 and 3060 feet with the valley floor gradually decreasing in elevation to the east and crossing the 3000 foot contour line south and east of Hingham. Elevations in section 29 north and west of Hingham rise to more than 3180 feet while elevations near the figure 8 southwest corner rise to more than 3200 feet. In other words the through valley is at least 120 feet deep and probably was deeper when eroded. South of Hingham Lake along the boundary between sections 1 and 6 and then south along the boundary between sections 12 and 7 is a much more subtle north-south oriented through valley which is linked to an east-oriented England Coulee tributary valley in sections 18 and 17. The north-south oriented through valley floor elevation is between 3060 and 3070 feet with elevations in section 7 (east of the through valley) rising to more than 3090 feet and elevations west of the through valley rising much higher. This north-south oriented through valley is shallow compared to the Hingham Coulee-England Coulee through valley, but it exists and documents what for a time was an alternate flood flow channel when south-oriented flood waters were flowing in anastomosing channels across the region. Headward erosion of the deep east-southeast oriented Hingham Coulee-England Coulee through valley beheaded the south-oriented flood flow in this north-south oriented through valley and subsequently O’Brien Coulee valley headward erosion further to the north beheaded flood flow routes moving across the figure 8 map area and the figure 8 landscape has remained relatively unchanged since that time.

England Coulee-Faulkner Coulee drainage divide area

Figure 9: England Coulee-Faulkners Coulee drainage divide area.United States Geological Survey map digitally presented using National Geographic Society TOPO software.

 

  • Figure 9 is a reduction of a less detailed topographic map to illustrate the England Coulee-Faulkners Coulee drainage divide area and includes significant overlap areas with figure 7. Proceeding eastward along the highway from the figure 9 northwest corner the towns encountered are Inverness, Rudyard, Hingham, Gildford,  and Kremlin (in the figure 9 northeast corner). Sage Creek flows in a south-southeast and southeast direction from the figure 9 north edge (near Gildford) to the figure 9 east center edge and joins northeast-oriented Big Sandy Creek east of the figure 9 map area. Northeast-oriented Big Sandy Creek can just barely be seen crossing the figure 9 southeast corner and joins the southeast and east oriented Milk River east of the figure 9 northeast corner. England Coulee drains in a southeast and east direction from the Hingham area to join Sage Creek south of Gildford. South of England Coulee is northeast and east oriented Faulkners Coulee which also drains to Sage Creek. South of Faulkners Coulee is east-northeast oriented Halfway Coulee, which joins Sage Creek near the figure 9 east center edge. South of Halfway Coulee, and in the figure 9 southeast corner region, are east- and south-oriented Jerome Coulee and east-southeast oriented Barneys Coulee. Jerome Coulee and Barneys Coulee drain to northeast-oriented Big Sandy Creek. South of the northeast-oriented Faulkner Coulee headwaters is south-southwest and southeast oriented Fourteenmile Coulee, which south of the figure 9 map area drains to northeast-oriented Big Sandy Creek. Note how the north-oriented Faulkner Coulee headwaters are linked by a well-defined shallow through valley with the south-oriented Fourteenmile Coulee headwaters. The through valley provides evidence of a former south-oriented flood flow channel, which was beheaded by headward erosion of the east-oriented Faulkners Coulee valley. The through valley can be traced north of the Faulkners Coulee north-oriented valley segment to the east-oriented England Coulee valley. Headward erosion of the east-oriented England Coulee valley beheaded the south-oriented flood flow subsequent to Faulkners Coulee valley headward erosion. South of Inverness and Rudyard is east, southeast, south, southwest, and south-oriented East Fork Black Coulee, which south of the figure 9 map area drains to the Marias River, which in turn flows to the Missouri River. As seen in figure 7 there are shallow north-south oriented through valleys between Rudyard and Hingham linking the southeast and east-oriented Sage Creek tributary valleys with south-oriented East Fork Black Coulee tributary valleys. Remember the Marias-Missouri River and the Milk River use different routes to flow around Bears Paw Mountains even though valleys west of the Mountains link their drainage basins.

Detailed map of England Coulee-Faulkners Coulee drainage divide area

Figure 10: Detailed map of England Coulee-Faulkners Coulee 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 England Coulee-Faulkners Coulee drainage divide area seen in much less detail in figure 9. England Coulee drains in an east direction north of the figure 10 map area. The east-northeast and north-northeast oriented stream flowing from section 36 near the figure 10 west edge to the figure 10 north center edge is an England Coulee tributary. Faulkners Coulee is labeled and can be seen draining in an east direction near the figure 10 south edge (east half). The north-south oriented through valley linking the England Coulee valley with the Faulkners Coulee valley shows up much better on figure 10 (than figure 9) and is seen in sections 3, 4, 9, and 10. The figure 10 map contour interval is ten feet and the through valley floor elevation is between 2870 and 2880 feet in its deepest channel. Elevations in section 35 to the east rise to 2935 feet while elevations in section 12 near the figure 10 southwest corner rise to 3091 feet. Based on the eastern elevation the through valley is at least 55 feet deep, although based on the western elevation the through valley may be more than 100 feet deep. Study of the figure 10 reveals other shallower and more subtle through valleys crossing other drainage divide areas. For example near the figure 10 southwest corner between sections 12 and 7 a shallow and higher level through valley crosses the drainage divide between the England Coulee tributary and a southeast-oriented Faulkners Coulee tributary. That higher level through valley floor elevation is between 3030 and 3040 feet with elevations to the east in section 7 rising to more than 3050 feet. Evidence presented in figure 10 documents multiple south-oriented flood flow channels with various floor elevations crossing the figure 10 map area and documents erosion of several tens of feet of bedrock material from much of the figure 10 map area, with erosion probably being greater in the east than in the west. There are no markers seen in figure 10 to document how much melt water flood erosion occurred prior to the melt water flood events responsible for the landscape seen today in figure 10. Evidence presented in this essay suggests melt water floods eroded hundreds of feet of bedrock material from much of the Cottonwood Creek-Sage Creek drainage divide and again this erosion was probably associated with what were the decaying ice sheet’s final rapid melt down flood erosion events and how much erosion occurred during earlier flood erosion events cannot be determined from evidence seen in this essay.

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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