South Saskatchewan River-Big Muddy Creek drainage divide landform origins, southern Saskatchewan, Canada

Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the South Saskatchewan River-Big Muddy Creek drainage divide area located south and west of the northeast-facing Missouri Escarpment in southern Saskatchewan. Today a southeast and south oriented discontinuous drainage route extends from the deep northeast-oriented South Saskatchewan River valley edge to the southeast and south oriented Big Muddy Creek valley, which drains to the Missouri River in northeast Montana. Along this discontinuous drainage route is the Chaplin Lake basin, southeast oriented Chaplin Creek, the Old Wives Lake basin, and a south- and southeast oriented valley partially filled by narrow and elongate lakes. This southeast and south-oriented discontinuous drainage route is what remains of what was once a major southeast and south oriented melt water flood flow channel, which was located along what was at that time the southwest margin of the detached southwest margin of the rapidly melting North American ice sheet. Headward erosion of the deep northeast-oriented South Saskatchewan River valley captured the southeast oriented melt water flood flow and beheaded all flood flow routes to the Big Muddy Creek valley. North and east of this southeast- and south-oriented Big Muddy Creek flood flow channel is the northeast-facing Missouri Escarpment, which is what remains of the southwest wall of a giant southeast-oriented ice-walled and bedrock-floored canyon which was carved into the decaying ice sheet’s surface. Flood waters flowing on this giant canyon’s floor originally drained to the Missouri River (in southeast South Dakota), although the opening up of east and north oriented drainage routes across the decaying ice sheet floor systematically dismembered the southeast-oriented melt water river and diverted flood flow in the giant canyon east and north. Headward erosion of the deep northeast-oriented South Saskatchewan River valley was one of these systematic flood flow capture events, however, unlike in previous capture events, the South Saskatchewan River valley capture event resulted in a deep northeast-oriented valley, which eroded headward across the detached ice sheet southwest margin to capture immense southeast oriented ice-marginal melt water floods (flowing to what were then actively eroding south oriented Missouri River tributary valleys such as the Big Muddy Creek valley) and to divert those ice-marginal flood waters in a northeast direction across the decaying ice sheet’s floor to what is now Hudson Bay.

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 South Saskatchewan River-Big Muddy Creek drainage divide area landform origins in Southern Saskatchewan, Canada. 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 essay 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 South Saskatchewan River-Big Muddy Creek drainage divide area landform evidence in southern Saskatchewan will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see menu at top of page for paradigm related essay). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

South Saskatchewan River-Big Muddy Creek drainage divide area location map

Figure 1: South Saskatchewan River-Big Muddy Creek drainage divide area location map (select and click on maps to enlarge). All maps used in this essay were downloaded from the Natural Resources Canada Toporama website. The large grid identifies 1:250,000 topographic map sheets and detailed grid identifies 1:50,000 topographic map sheets. 
  • The Missouri River drainage basin extends northward into southern Alberta and Saskatchewan and the south-oriented Big Muddy Creek drainage basin is the easternmost Missouri River drainage basin in southern Saskatchewan. The South Saskatchewan River is a major east and northeast-oriented river in Saskatchewan, which after joining the North Saskatchewan River forms the northeast-oriented  Saskatchewan River, which flows to the northeast-oriented Nelson River, which in turn flows to Hudson Bay. In other words the South Saskatchewan River-Big Muddy Creek drainage divide area investigated in this essay is the north-south continental divide. Figure 1 is a Natural Resources Canada index map for 1:250,000 and 1:50,000 scale hard copy topographic maps of southern Saskatchewan (west of the Manitoba border). The border with the United States is where the index map grid ends. Numbers used to identify specific topographic map sheets will be useful in identifying locations of the topographic maps illustrated in the following discussion and also for identifying drainage routes, which frequently are not labeled. The South Saskatchewan River valley is flooded by Lake Diefenbaker in the figure 1 northwest corner area and is oriented in a northeast and northwest direction. A northwest oriented Lake Diefenbaker arm floods the valley of a northwest oriented tributary, which enters the South Saskatchewan River valley at Elbow. Lake Diefenbaker floods the northwest-oriented tributary valley to the point that a dam has been built at the southeast end of that Lake Diefenbaker arm to prevent South Saskatchewan River water from flowing down the southeast-oriented Qu’Appelle River valley. The Qu’Appelle River flows in a southeast direction to map 72I11 where it joins the northwest- and north-oriented Moose Jaw River and turns to flow in more of an east direction to the figure 1 east edge. East of figure 1 the Qu’Appelle River flows to east-oriented Assiniboine River, which joins the north-oriented Red River, with water eventually reaching the Nelson River. While not visible on figure 1 south and west of the southeast-oriented Qu’Appelle River valley is the northeast-facing Missouri Escarpment, which will be seen in the topographic maps below.
  • The northwest-southeast oriented through valley linking what is today a northwest-oriented South Saskatchewan River valley segment with the southeast oriented Qu’Appelle River headwaters valley is just one of many northwest-southeast oriented through valleys linking northwest and southeast oriented valleys in the figure 1 map region. Map number 72H16 illustrates another through valley location linking the northwest-oriented Moose Jaw Creek headwaters with  the southeast-oriented Souris River headwaters neat Yellow Grass. The Souris River is unlabeled, but originates as a northwest-oriented stream and then makes a U-turn to flow in a southeast direction to Weyburn and Estevan before flowing to Oxbow in map number 62E1. Just east of map 62E1 the Souris River turns to flow in a south direction into North Dakota. Once in North Dakota the Souris River again flows in a southeast direction near the base of the northwest-southeast oriented and northeast-facing Missouri Escarpment until the Sours River makes a large U-turn to flow in a northwest and north direction to join the east-oriented Assiniboine River, with water eventually reaching the Nelson River and Hudson Bay. Continuing in a southeast direction along the Missouri Escarpment base from the Souris River North Dakota U-turn leads to the Sheyenne and James River headwaters valleys. The Sheyenne River is located slightly north and east of the James River, although the two rivers begin in the same general region of central North Dakota and flow sometimes almost adjacent to each other and roughly parallel to the nearby southeast- and south-oriented Missouri Escarpment base for considerable distances. Yet, eventually the Sheyenne River makes a giant U-turn and flows in a northeast direction to join the north-oriented Red River while the James River continues to flow in a south direction (roughly parallel to the Missouri Escarpment base) into South Dakota and eventually to join the Missouri River. Essays may be located by using appropriate sidebar categories.
  • Big Muddy Creek is shown as a southeast oriented stream flowing south from the lake in map number 72H2 into the United States (Montana). The drainage route on figure 1 appears discontinuous along the international border, but is in fact continuous. The lake is Big Muddy Lake and the southeast-oriented drainage originating in the southeast quadrant of map 72H3 is Beaver Creek, which south of the figure 1 map area joins Big Muddy Creek. South of the figure 1 map area Big Muddy Creek flows to the Missouri River. South oriented drainage crossing the international border west of Beaver Creek flows to the Poplar River, which is also a Missouri River tributary. As will be seen in the topographic maps below the Big Muddy Creek valley extends in northwest direction to the Old Wives Lake basin in map number 72I4 and there is a continuous southeast-oriented drainage route from the southeast rim of the Old Wives Lake basin across maps 72I13, 72I12, 72H15 (northeast corner), and 72H6 to the continuous Big Muddy Creek drainage seen in the map number 72H3 southeast quadrant. This discontinuous drainage route is located in a large valley in which several elongate lakes are located. The southeast-oriented stream flowing to Old Wives Lake is Chaplin Creek, which as will be seen in the topographic maps is linked by a shallow through valley with the South Saskatchewan River valley. Drainage divides located directly south of the international border are described in the Big Muddy Creek-Little Muddy Creek drainage divide landform origins essay and in the Poplar River-Big Muddy Creek drainage divide area landform origins essay. Between the southeast-oriented Big Muddy Creek valley (including the Chaplin Creek valley and Old Wives Lake basin) and the northwest-oriented Moose Jaw Creek and southeast-oriented Souris River drainage basin is an upland region known as the Missouri Coteau and then the northeast-facing Missouri Escarpment along the southwest margin of the broad Moose Jaw Creek-Souris River through valley. The Missouri Coteau is an area of hummocky topography typical of glacial moraine areas and is generally poorly drained. The Missouri Escarpment and Missouri Coteau extend in a southeast direction from east central Alberta across Saskatchewan to the North Dakota northwest corner and then to central North Dakota, where the Missouri Escarpment becomes an east-facing escarpment and the Missouri Escarpment and Missouri Coteau then continue southward into south central South Dakota. South and west of the Missouri Coteau in North and South Dakota is the southeast- and south-oriented Missouri River valley.

Big Muddy Creek-Souris River drainage divide area

Figure 2: Big Muddy Creek-Souris River drainage divide area from 1:300,000 scale topographic maps (scales identified for topographic maps in this essay are scales as identified by Toporama).  
  • Figure 2 is a topographic map of the Big Muddy Creek-Souris River drainage divide located just north of the international border. Weyburn, Saskatchewan is located in the figure 2 northeast corner and the Souris River flows in a southeast direction through Weyburn. The southeast oriented stream flowing through Radville in map number 72H8 is Long Creek, which is a Souris River tributary. Immediately to the southwest of Long Creek is the northeast-facing Missouri Escarpment, which rises approximately 100 meters. South and west of the Missouri Escarpment is what appears to be a relatively level, but poorly drained upland surface with a number of small lakes. This upland region is the Missouri Coteau and on more detailed topographic maps is a hummocky region with numerous small depressions, typical of regions covered with glacially deposited debris. The broad northwest-southeast oriented Souris River lowland located north and east of the Missouri Escarpment base is much better drained, which is evident from the abundance of drainage routes seen in figure 2. The southeast-oriented deep valley seen in map number 72H2 and the southwest corner of map number 72H3 is a northwest-oriented tributary valley to the southeast- and south-oriented Big Muddy Creek valley, which is located just west of the figure 2 map area. While not quite as deep as the Souris River lowland to the east the lake in the Big Muddy Creek valley (seen along the figure 2 west edge in map number 72H2) has an elevation of 660 meters, which is more than 80 meters lower than the Missouri Coteau upland to the east and north.
  • As already noted the Missouri Escarpment and Missouri Coteau extend from east central Alberta to southern South Dakota. East and north of the Missouri Escarpment are drainage routes which flow roughly parallel to the Escarpment for a distance then turn to eventually flow in north directions to Hudson Bay (except for the James River in North and South Dakota, which flows in a south direction to join the Missouri River). West and south of the Missouri Coteau in South and North Dakota is the deep Missouri River and in southern Saskatchewan as seen in figure 2 is the Big Muddy Creek valley. While viewing a much larger region is necessary to see the big picture view, the Missouri Escarpment is what remains of the southwest and west wall of a giant southeast and south-oriented ice-walled and bedrock-floored canyon which was carved into the surface of a rapidly melting North American ice sheet. The ice-walled and bedrock-floored canyon was carved by an immense southeast and south-oriented supra glacial melt water river, which flowed to the decaying ice sheet margin in southeast South Dakota. Flood waters in that immense melt water river played a major role in eroding the Missouri River valley downstream from Yankton, South Dakota. The giant ice-walled and bedrock-floored canyon detached the ice sheet’s southwest margin, which then melted slowly and deposited whatever debris it contained to form the Missouri Coteau. Large ice-marginal floods moving in a southeast and south directions along the detached ice sheet margin eroded the deep Missouri River valley and the southeast and south-oriented Big Muddy Creek valley. Southeast-oriented flood flow in the giant ice-walled and bedrock-floored canyon was systematically dismembered when ice sheet melting opened up drainage routes to the east and north. During this dismemberment process the northwest-oriented South Saskatchewan River valley segment north of Elbow was eroded by reversed flood flow, and the northeast-oriented South Saskatchewan River valley, eroded across the decaying detached ice sheet margin, and captured all southeast-oriented ice marginal flood flow to what was then the actively eroding Big Muddy Creek valley.

Little Poplar River-Big Muddy Creek drainage divide area

Figure 3: Little Popular River-Big Muddy Creek drainage divide area from 1:300,000 scale Toporama map.
  • Figure 3 illustrates the Poplar River-Big Muddy Creek drainage divide area west of the figure 2 map area and includes overlap areas with figure 2. The Big Muddy Creek valley extends from the northeast corner of map 72H3 into map number 72H2 and then meanders in a south direction from the lake to the figure 3 south edge. The northwest-oriented Big Muddy Creek tributary valley seen in figure 2 extends from the figure 3 southeast corner and probably was eroded as southeast oriented valley, which was subsequently blocked by glacial debris. Note how the Big Muddy Creek valley extends in a northwest direction into maps numbered 72H6 and 72H5, although no continuous drainage route is shown. Instead elongate lakes fill valley segments, suggesting the large southeast and south oriented valley no longer serves as a continuous drainage route. South and southeast oriented drainage in the map 72H3 east half flows to Beaver Creek, which south of the figure 3 map area (in Montana) joins Big Muddy Creek. Note how the Beaver Creek headwaters originate on the rim of an east-oriented Big Muddy Creek valley segment, which is approximately 100 meters higher than the Big Muddy Creek valley floor. This evidence suggests the east-oriented Big Muddy Creek valley segment was eroded headward across south and southeast oriented flood flow moving on a topographic surface at least as high as the Big Muddy Creek valley-Beaver Creek drainage divide today. Note north-oriented tributaries flowing into the east-oriented Big Muddy Creek valley segment. Those north-oriented tributary valleys were eroded by reversals of flood on north ends of beheaded south-oriented flood flow routes. The Little Poplar River is the south-southeast oriented drainage route flowing from map number 72H5 across the northeast corner of map number 72H4 and along the west margin of map number 72H3 to the international border. South of the border in Montana the Little Poplar River joins the southeast oriented Poplar River, which then flows to the Missouri River. Note how in map 72H5 the Little Poplar River headwaters near Willow Bunch originate on the rim of the deep southeast oriented Big Muddy Creek valley. This evidence further suggests the deep Big Muddy Creek valley was eroded headward across southeast and south oriented flood flow moving on a topographic surface at least as high as the present day Big Muddy Creek valley-Little Poplar River drainage divide. In other words, immense southeast- and south-oriented ice-marginal floods flowed along the southwest margin of the detached ice sheet’s southwest margin. Headward erosion of the deep Big Muddy Creek valley captured the southeast- and south-oriented flood flow and eroded the deep valley seen today. As described in the Big Muddy Creek-Little Muddy Creek drainage divide landform origins essay and in the Poplar River-Big Muddy Creek drainage divide area landform origins essay the Big Muddy Creek valley probably initially eroded headward from a large northeast oriented valley, which was subsequently blocked when the decaying ice sheet was rejuvenated. Today the Big Muddy Creek drainage route extends across that abandoned northeast-oriented valley to the present day Missouri River valley.

Big Muddy Creek-Moose Jaw River drainage divide drainage divide area

Figure 4: Big Muddy Creek-Moose Jaw River drainage divide area from 1:300,000 scale Toporama map.
  • Figure 4 illustrates the Big Muddy Creek-Moose Jaw River drainage divide area north of the figure 3 map area and includes overlap areas with figure 3. The elongate lake in map 72H13 is a northern extension of the Big Muddy Creek valley (although today there is no continuous drainage through the valley) and continues southward to the southeast-oriented elongate lake in the figure 4 southwest corner area (which was seen in figure 3). The northwest oriented stream in the figure 4 northeast corner is Moose Jaw River, which north and east of the figure 4 map area joins the east-oriented Qu’Appelle River, with water eventually reaching Hudson Bay. The northwest oriented stream in map 72H15 is Avonlea Creek, which turns near the map 72H15 northwest corner to flow in a north direction to join the Moose Jaw River just north of the figure 4 map area. South and west of Avonlea Creek is the northeast-facing Missouri Escarpment. Note the numerous northeast-oriented Avonlea Creek tributaries flowing down the escarpment face and how drainage north and east of the Missouri Escarpment is now oriented in a northwest direction, even though today there is no topographical barrier between the northwest-oriented Moose Jaw River drainage and the southeast-oriented Souris River drainage seen in figure 2. Southeast-oriented melt water flood flow in the giant southeast-oriented ice-walled and bedrock-floored canyon was beheaded and reversed by headward erosion of the east-oriented Qu-Appelle River valley (on the floor of an east-oriented ice-walled and bedrock-floored canyon). Subsequently southeast oriented flood flow to the newly developed east-oriented Qu’Appelle River ice-walled and bedrock-floored canyon was beheaded when melt water flood flow in a southwest-oriented tributary ice-walled and bedrock-floored canyon was reversed to flow toward present day Hudson Bay and to create the northwest- and northeast-oriented South Saskatchewan River drainage route. Note the northeast oriented Moose Jaw River tributary valley in which the community of Spring Valley is located (northwest quadrant of map 72H14). Hills surrounding that tributary valley may be ice thrust slabs of bedrock moved at the time the decaying ice sheet was rejuvenated. The ice sheet rejuvenation occurred because, as north-oriented drainage routes opened up in the maze of ice-walled and bedrock-floored canyons developing on the decaying ice sheet’s floor, massive reversals of the south-oriented melt water floods took place. Evidence for these reversals is found in U-turns made by major rivers today and through valleys (such as the Moose Jaw River-Souris River through valley). These massive meltwater flood reversals greatly diminished melt water flood flow to the Gulf of Mexico and greatly increased melt water flood flow to the North Atlantic (and perhaps the Arctic Ocean). The result was a major change in ocean currents, which in turned cooled the Northern Hemisphere climate, which caused the north-oriented melt water floods to freeze on the floors of the ice-walled and bedrock-floored canyons. The result was a new thin ice sheet with remnants of decaying thick ice sheet embedded in it. Subsequent thin ice sheet movements picked up and moved slabs of the underlying frozen bedrock which today often form hills.

Old Wives Lake-Moose Jaw River drainage divide area

Figure 5: Old Wives Lake-Moose Jaw River drainage divide area from 1:300,000 scale Toporama map. 
  • Figure 5 illustrates the Old Wives Lake-Moose Jaw Creek drainage divide area north and west of the figure 4 map and includes overlap areas with figure 4. Moose Jaw is the city located near the figure 5 northeast corner. Moose Jaw River flows in a northwest direction to Moose Jaw and then turns to flow in an east, northeast, and north direction (east and north of figure 5) to join the Qu’Appelle River. The southeast oriented stream joining the northwest-oriented Moose Jaw River segment at Moose Jaw is Thunder Creek, which will be seen again in figures 7, 8, and 9. Note how the northwest-oriented Moose Jaw River segment and  southeast oriented Thunder Creek flow along the northeast-facing Missouri Escarpment base. The northwest-oriented Moose Jaw River valley was eroded by a reversal of southeast oriented flood flow beheaded by headward erosion of the east-oriented Qu’Appelle River valley (which was probably eroded on the floor of an east-oriented ice-walled and bedrock-floored canyon, which captured southeast oriented flood flow moving in the ice-walled and bedrock-floored canyon east of the Missouri Escarpment). Hills along the Escarpment crest may be ice thrust slabs as described in figure 4. Old Wives Lake is located in the northwest extension of the large Big Muddy Creek valley seen in previous figures, although today Old Wives Lake is a closed basin with no outlet. The southeast-oriented stream flowing to join a northeast-oriented stream near the northwest end of Old Wives Lake is Chaplin Creek, seen again in figures 7 and 8. The northeast-oriented stream, which Chaplin Creek joins near the Old Wives Lake northwest end, is the Wood River, seen again in figure 6. Note how elevations between the southeast-oriented Chaplin Creek-Old Wives Lake-Big Muddy Creek valley and the Missouri Escarpment are higher than elevations west of the southeast-oriented valley. While better seen in figure 6 the areas between the north-northeast oriented Wood River and the discontinuous drainage in the southeast- and south-oriented Chaplin Creek-Old Wives Lake-Big Muddy Creek valley was deeply eroded by southeast-oriented flood flow to the Big Muddy Creek valley prior to a major flood flow reversal that eroded the north-northeast oriented Wood River valley west of figure 5. These ice-marginal melt water flood events occurred at a time when decaying ice was still present in the Missouri Coteau region, which separated flood flow movements east and north of Missouri Escarpment from flood flow movements south and west of the southeast- and south-oriented Chaplin Creek-Old Wives Lake-Big Muddy Creek valley. The Old Wives Lake basin probably formed when the southeast-oriented Chaplin Creek-Old Wives Lake-Big Muddy Creek melt water flood flow channel became blocked by either southeast-oriented flood transported debris from the west and/or by glacial debris from the northeast (perhaps moved by the rejuvenated, but detached southwest ice sheet margin), although the figure 5 map is not detailed enough to determine which.

Wood River-Big Muddy Creek drainage divide area

Figure 6: Wood River-Big Muddy Creek drainage divide area from 1:300,000 scale Toporama map.
  • Figure 6 illustrates the Wood River-Big Muddy Creek drainage divide area west of the figure 4 map area and south and west of the figure 5 map area and includes overlap areas with figures 4 and 5. Old Wives Lake is located in maps 72H14 and 72J1 and the south-oriented north extension of the Big Muddy Creek valley is located in maps 72H13 and 72H12. Remember drainage in the northern valley extension is today discontinuous drainage and the valley floor is today covered by shallow elongate lakes, although the valley at one time was the route of a continuous southeast and south-oriented melt water flood flow channel. The north-northeast oriented stream in maps 72G10, 72G15, and 72G16 (northwest corner) is the Wood River, which as seen in figure 5 flows to Old Wives Lake, and is the major drainage route in what is today the Old Wives Lake internal drainage basin. Note how the north-northeast oriented Wood River has northwest-oriented tributaries from the east. Note also areas of higher elevation in maps 72G7 and 72G8 and generally in the figure 6 southwest corner area. These higher elevations represent remnants of a topographic surface that once extended northward across the entire figure 6 map area. Melt water flood erosion lowered the surface  north of the elongate lake in map 72G8, which is Twelve Mile Lake. Twelve Mile, while draining in a northwest direction today, is located in a former east-oriented flood flow channel which once drained to the Big Muddy Creek valley. North of Twelve Mile Lake the landscape has been eroded by southeast oriented ice-marginal melt water flood flow, which once moved to what was then the actively eroding Big Muddy Creek flood flow channel (located along the southwest margin of what was then the detached and decaying southwest margin of the former thick North American ice sheet). At the time flood waters were flowing across the figure 6 map area the deep northeast-oriented South Saskatchewan River valley did not yet exist and ice-marginal melt water flood waters were flowing to and along the ice sheet’s decaying margin. The north-northeast oriented Wood River valley was eroded by a reversal of flood flow triggered by headward erosion of the deep southeast and south-oriented Big Muddy Creek flood flow channel (perhaps aided by reversals of flood flow further to the north as northern drainage routes across the former ice sheet floor began to open up). The northwest-oriented Wood River tributary valleys were also eroded by reversals of flood flow on northwest ends of flood flow routes beheaded by headward erosion of the north-northeast oriented Wood River valley.

Chaplin Creek-Thunder Creek drainage divide area

Figure 7: Chaplin Creek-Thunder Creek drainage divide area from 1:300,000 scale Toporama map.
  • Figure 7 illustrates the Chaplin Creek-Thunder Creek drainage divide area north and west of the figure 5 map area and includes overlap areas with figure 5. Chaplin Creek is the southeast oriented stream in the northwest quadrant of map 72J1, which is draining the elongate lake in map 72J7. The lake in map 72J7 is Chaplin Lake (note the town of Chaplin on the north side of the lake) and is another shallow lake located in the northwest extension of the Big Muddy Creek valley. Chaplin Lake drains via Chaplin Creek to Old Wives Lake, which is located in maps 72J1 and 72I4 and which as previously stated is today a closed basin, although should the Old Wives Lake basin ever fill to overflowing the water would flow in a south and southeast direction to the Big Muddy Creek valley. The northwest, northeast, southeast and northeast-oriented stream joined by Chaplin Creek at the Old Wives Lake west end is the Wood River and is joined in map 72J2 (southeast corner) by southeast-oriented Wiwa Creek. The southeast, east-northeast, and southeast oriented stream in map 72J9 and flowing to the figure 7 east center edge is Thunder Creek, which joins northwest-oriented Moose Jaw Creek at Moose Jaw (see figure 5) which then flows in an east, northeast, and north direction to join the east-oriented Qu’Appelle River. Note how Thunder Creek is flowing near the base of the northeast-facing Missouri Escarpment on a topographic surface approximately 100 meters lower than elevation of region surrounding Chaplin Lake. The Missouri Escarpment face appears to have been eroded by flood waters spilling across the ice sheet’s detached southwest margin onto the deeper floor of the southeast-oriented ice-walled and bedrock-floored canyon, which once drained to the actively eroding Missouri River valley (in southeast South Dakota). Indentations eroded by such ice-marginal spillage onto the deeper southeast-oriented ice-walled and bedrock-floored canyon floor were probably subsequently altered by movements of the wet-based thin ice sheet, which later filled the ice-walled and bedrock-floored canyon, and which probably lifted slabs of frozen bedrock onto the escarpment crest. What is most important to note in figure 7 is the southeast-oriented drainage in both the Chaplin Lake and Chaplin Creek valley and the Thunder Creek valley, which are located on opposites of the northeast-facing Missouri Escarpment and Missouri Coteau ridge.

South Saskatchewan River-Chaplin Creek drainage divide area

Figure 8: South Saskatchewan River-Chaplin Creek drainage divide area.
  • Figure 8 illustrates the South Saskatchewan River-Chaplin Creek drainage divide area north and west of the figure 7 map area and includes overlap areas with figure 7. Chaplin Lake is located in map 72J7 and as seen in figure 7 drains in a south and southeast direction to Old Wives Lake south of the figure 8 map area. The South Saskatchewan River flows in a northeast direction across the figure 8 northwest quadrant and the valley has been flooded by Lake Diefenbaker. The southeast tip of a Lake Diefenbaker arm can be seen in the northwest corner of map 72J16. Note the dam at the southeast end of that Lake Diefenbaker arm, which prevents the flooded South Saskatchewan River from flowing in a southeast direction down the southeast oriented Qu’Appelle River valley (see figure 1). Thunder Creek flows in a southeast direction to the south edge of map 72J15 and then in a south and east direction across the map 72J10 northeast quadrant and into map 72J9 and to the figure 8 east edge. Note how Thunder Creek begins almost on the edge of the South Saskatchewan River valley as a west-oriented stream flowing towards the South Saskatchewan River and then turns to flow away from the nearby South Saskatchewan River valley. Also note how the Thunder Creek headwaters flow along the base of the northeast-facing Missouri Escarpment and how the South Saskatchewan River has carved a deep northeast-oriented valley across the Missouri Escarpment and the Missouri Coteau area to the southwest of the Escarpment. In addition note how broad through valleys eroded into the surface west of the Missouri Escarpment in the northwest corner of map 72J10 and the map 72J11 northeast quadrant link the southeast oriented Chaplin Lake valley with northeast-oriented South Saskatchewan River valley. While in the context of modern-day drainage routes this figure 8 map area is well removed from the Missouri River drainage basin and even the Big Muddy Creek drainage basin. However, this essay has followed the northwest extensions of the southeast and south-oriented Big Muddy Creek valley and the southeast oriented Souris River valley (seen on opposite sides of the Missouri Escarpment) headward to the deep South Saskatchewan River valley. Figure 8 shows southeast-oriented flood flow to the southeast and east oriented Qu’Appelle River valley was beheaded by northeast-oriented South Saskatchewan River valley headward erosion. Figure 8 map evidence also demonstrates the southeast-oriented Big Muddy Creek valley received southeast-oriented ice-marginal flood flow prior to headward erosion of the deep northeast-oriented South Saskatchewan River valley. Probably headward erosion of the deep northeast-oriented South Saskatchewan River valley occurred at a time when deep northeast-oriented drainage routes were opening up across the floor of the rapidly decaying thick North American ice sheet. Prior to that time flood flow both along the ice sheet margin (e.g. in the Big Muddy Creek valley) and in ice-walled and bedrock-floored canyons (e.g. east and north of the northeast-facing Missouri Escarpment) had been in southeast and south directions.

Detailed map of South Saskatchewan-Thunder Creek drainage divide area

Figure 9: Detailed map of South Saskatchewan River-Thunder Creek drainage divide area from Toporama 1:150,000 scale map.
  • Figure 9 illustrates in more detail (than figure 8) the South Saskatchewan River-Thunder Creek drainage divide area east of the northeast-facing Missouri Escarpment, which was seen in less detail in figure 8. Lake Diefenbaker, which floods the northeast-oriented South Saskatchewan River valley, is seen in the figure 9 northwest quadrant. Thunder Creek originates in map 72J15 as a west-oriented stream, but makes a U-turn to flow in a southeast direction to Paysen (Horfield) Lake and then to flow in a southeast and east direction to the town of Thunder Creek and the figure 9 east edge (south half). Note how the 100 meter plus high Missouri Escarpment is located west of Thunder Creek and south of the South Saskatchewan River valley. Thunder Creek in the figure 9 map area is flowing along the southwest margin of a northwest-southeast oriented broad lowland between the Missouri Escarpment and uplands defined by such areas as Last Mountain and the Moose Mountains (neither is seen in maps illustrated in this essay). Today the northwest end of this broad northwest-southeast oriented lowland is drained by southeast oriented Qu’Appelle River tributaries and headwaters. As seen in earlier figures in this essay southeast of the southeast oriented Qu’Appelle River tributaries and headwaters the northwest-southeast oriented broad lowland is drained by northwest-oriented Qu’Appelle River tributaries and further to the southeast by southeast oriented Souris River headwaters and tributaries. As previously mentioned the broad lowland can be followed in a southeast direction along the northeast-facing Missouri Escarpment base into central North Dakota and to the south-oriented James River lowland, which is a south-oriented broad lowland located east of the east facing Missouri Escarpment in south central North Dakota and central South Dakota. East of the James River lowland in South Dakota is the west-facing Prairie Coteau Escarpment and the Prairie Coteau upland, which is what remains of the east wall of the giant southeast and south-oriented ice-walled and bedrock-floored canyon. Remnant’s of the ice-walled and bedrock-floored canyon’s northeast wall in north central North Dakota and southern Saskatchewan include the Turtle Mountain, Moose Mountain, and Last Mountain southwest escarpments. Originally an immense river on the floor of this giant southeast- and south-oriented ice-walled and bedrock-floored canyon drained melt water floods from the rapidly melting ice sheet surface to the actively eroding Missouri River valley (downstream from southeast South Dakota). The opening up of east and north-oriented drainage routes across the decaying ice sheet floor captured this southeast-oriented flood flow first in southeast North Dakota to produce the present day Sheyenne River valley U-turn. Next the southeast-oriented melt water river was captured in north central North Dakota to create the Souris River U-turn. The southeast-oriented melt water river was captured again north and east of Moose Jaw by headward erosion of the east-oriented Qu’Appelle River valley. And next headward erosion of the deep northeast-oriented South Saskatchewan River valley beheaded and reversed southeast-oriented flood flow routes to the newly eroded Qu’Applelle River valley to erode the northwest-oriented South Saskatchewan River valley segment seen northwest of Elbow (seen in figure 1).

Detailed map of South Saskatchewan River-Chaplin Creek drainage divide area

Figure 10: Detailed map of South Saskatchewan River-Chaplin Creek drainage divide area from Toporama 1:150,000 scale map.
  • Figure 10 illustrates in more detail the South Saskatchewan River-Chaplin Lake drainage divide area seen in less detail in figure 8 above (and also located west and south of the figure 9 map area and includes overlap areas with figure 9). Lake Diefenbaker, which floods the northeast-oriented South Saskatchewan River valley can be seen along the figure 10 north edge. The southeast oriented broad valley draining to the figure 10 southeast corner is the northwest extension of the Chaplin Lake valley, which drains in a southeast direction via Chaplin Creek to the Old Wives Lake basin. As seen in earlier figures the Old Wives Lake basin, should it ever overflow, would drain in a south and southeast direction to the southeast and south oriented Big Muddy Creek valley. Note how the southeast-oriented Chaplin Lake valley is linked by broad through valleys with the much deeper South Saskatchewan River valley. One such through valley extends south from Log Valley and is bounded by hills on either side defined by two or more 20-meter contour intervals. Another somewhat narrower through valley is located north and west of Glen Kerr (located near figure 10 center) and is also defined by two contour lines on each side. The Lake Diefenbaker surface elevation in the South Saskatchewan River valley is at least 140 meters lower than the floors of these through valleys, which originate almost on the edge of the present day South Saskatchewan River valley. This evidence suggests the deep northeast-oriented South Saskatchewan River valley eroded headward across multiple south and southeast-oriented flood flow channels west of the northeast-facing Missouri Escarpment (seen adjacent to the north half of the figure 10 east edge). The deep South Saskatchewan River valley has been carved into the higher topographic surface west and south of the Missouri Escarpment, which as previously described is what remains of the southwest wall of a giant southeast-oriented ice-walled and bedrock-floored canyon, which was carved into the decaying ice sheet’s surface. The south and southeast-oriented melt water flood flow which was captured by headward erosion of the deep South Saskatchewan River valley was flowing to what was then the actively eroding Big Muddy Creek valley, which at that time was generally located along the southwest margin of the detached southwest margin of the rapidly decaying ice sheet.

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 produced and/or compiled by Natural Resources Canada and were downloaded from the Natural Resources Canada Toporama web site. Hard copy maps can be obtained from dealers offering Natural Resource Canada topographic maps or may be observed in depository libraries located throughout Canada and elsewhere.

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