Milk River-Lodge Creek drainage divide area landform origins, southeast Alberta, Canada

Authors

Abstract:

Topographic map interpretation methods are used to determine landform origins in the Milk River-Lodge Creek drainage divide area located in the Alberta southeast corner. The Milk River flows in an east direction to the Alberta southeast corner and then turns to flow in a southeast direction into Montana. Lodge Creek is a southeast-oriented Milk River tributary located east of the southeast-oriented Milk River segment and originates in the southeast Alberta Cypress Hills. North and west of the Milk River-Lodge Creek drainage divide area is the Lake Pakowki basin, which today is an internal drainage basin, although it is linked by through valleys to the east-oriented Milk River valley in the south and by slightly lower through valleys to north and northeast oriented drainage routes to the northeast oriented South Saskatchewan River. Multiple through valleys are located between the southeast-oriented Milk River and Lodge Creek valleys linking northwest-oriented Lake Pakowki tributaries with discontinuous southeast-oriented streams flowing towards the Milk River drainage basin. The northwest-southeast oriented through valleys, while linking discontinuous stream in both directions, are interpreted to be crossing the Hudson Bay-Gulf of Mexico drainage divide and to have been eroded by immense southeast-oriented ice-marginal melt water floods during late stages of the rapid melt down of a thick North American ice sheet. The ice sheet had been located in a deep “hole” and the melt water floods deeply eroded the Milk River-Lodge Creek drainage divide area. Headward erosion of the deep northeast-oriented South Saskatchewan River valley and its northeast- and north-oriented tributary valleys is interpreted to have captured the southeast-oriented flood flow, with flood waters on northwest ends of beheaded flood flow channels reversing flow direction to erode northwest-oriented Lake Pakowki tributary valleys.

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 Milk River-Lodge Creek drainage divide area landform origins in southeast Alberta, 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 essay and then by leaving a comment here with a link to those essays.
  • This essay is also exploring a new geomorphology paradigm in which erosional landforms are interpreted as evidence left by immense glacial melt water floods. Implied in that interpretation is the immense floods were derived from a thick North American ice sheet that created a deep “hole” in the North American continent and also melted fast. The previously unexplored paradigm being tested in this and other essays in the Missouri River drainage basin landform origins research project is a thick North American ice sheet, comparable in thickness to the Antarctic ice sheet, occupied the North American region usually recognized to have been glaciated, and through its weight and erosive actions created a deep North American “hole”. The southwestern rim of that deep “hole” is today preserved in the high Rocky Mountains. The ice sheet through its weight and deep erosion (and perhaps deposition along major south-oriented melt water flow routes) caused significant crustal warping and tectonic change, through its action of melting fast produced immense floods that flowed across the continent, and through its action of melting fast systematically opened up space in the ice sheet created “hole” so headward erosion of newly developed north-oriented drainage systems captured immense south-oriented melt water floods and diverted immense melt water floods north into space the ice sheet had once occupied.
  • If this previously unexplored paradigm is correct the geographic region explored by this essay should contain evidence of immense floods that were captured by headward erosion of new valley systems so as to cause the floods to flow in a different direction. Ability of this previously unexplored paradigm to explain Milk River-Lodge Creek drainage divide area landform evidence in southeast Alberta, Canada 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.

Milk River-Lodge Creek drainage divide area location map

Figure 1: Milk River-Lodge Creek drainage divide area location map from Atlas of Canada Toporama index map (select and click on maps to enlarge).
  • Figure 1 is an Atlas of Canada index map from the Toporama web site identifying hard copy Canadian topographic maps for southern Alberta with Montana being located to the south, Saskatchewan to the east, and British Columbia to the west. The large grid in the Canadian areas identifies hard copy 1:250,000 scale topographic maps while the more detailed grid identifies 1:50,000 scale topographic maps. Grid numbers appear on all Toporama maps and can be used to identify Alberta locations in the figures illustrated below. The Milk River is not labeled in figure 1, but originates in Montana south of map 82H4 and flows in a northeast direction to enter Alberta in the southwest corner of map 82H2. From map 82H2 the Milk River flows in an east direction across southern Alberta to map 72E2 where it turns to flow in a southeast direction across the map 72E1 southwest corner and into Montana where it turns to flow in an east direction to the figure 1 east edge (just north of southeast corner). The Milk River flows to the Missouri River and then the Mississippi River with water eventually reaching the Gulf of Mexico. Lodge Creek originates in map 72E9 and flows in a southeast direction to join the Milk River near the figure 1 east edge. The Milk River-Lodge Creek drainage divide area investigated in this essay is centered in maps 72E1, 72E2, 72E7, and 72E8 and includes areas from adjacent maps. Note east-southeast oriented streams draining to and/or toward Pakowki Lake. Pakowki Lake appears to drain in a north direction to join the northeast-oriented South Saskatchewan River near Medicine Hat located in map 72L1, although today Lake Pakowki is an internal drainage basin with no regular outlet. The South Saskatchewan River  is not labeled in figure 1, but flows to the figure 1 east edge near map 72L16. Water in the South Saskatchewan River eventually reaches Hudson Bay. The drainage divide between the northeast-oriented South Saskatchewan River and the east- and southeast-oriented Milk River (and Lodge Creek) is today the north-south continental drainage divide. The Lodge Creek-Battle Creek drainage divide area landform origins in Saskatchewan and Alberta essay discusses region immediately east of the study and the Milk River-Battle Creek drainage divide area in Hill County, Montana essay discusses the region immediately to the south. Essays may be found by selecting Milk River from the sidebar category list.
  • Before looking at the southeast Alberta Milk River-Lodge Creek drainage divide area in detail an overview of the regional erosional history is needed. Southeast Alberta was deeply eroded during the rapid melt down of a thick North American ice sheet, which had been located in a deep “hole.” The upper Missouri River  drainage basin in Montana and northern Wyoming represents the deep “hole’s” southwest wall and high-level Rocky Mountain erosion surfaces are remnants of the upland surrounding surface, which may be deeply eroded remnants of the surface on which the ice sheet originally formed. At the time the ice sheet originally formed the Rocky Mountains did not exist (as topographic features at least) and the deep “hole” was formed by a combination of deep glacial erosion and of crustal warping caused by the ice sheet’s great weight. Crustal warping, perhaps aided by crustal unloading as massive south and southeast-oriented melt water floods flowed across what are today crests of high Rocky Mountain ranges, uplifted the Rocky Mountains, Rocky Mountain outliers, and western North American plateau areas from the south to the north diverting the south and southeast-oriented melt water floods in both east and west directions to erode present day river valleys including the Missouri River valley and its numerous tributary valleys. The Milk River valley in Alberta and Montana represented the last major Missouri River tributary valley to be eroded during this process. Long before erosion of the northeast, east, and southeast-oriented Milk River valley southeast Alberta was eroded by different deep east and northeast-oriented valleys, some of which probably were responsible for creating erosion and/or deposition surfaces capping the southeast Alberta and southwest Saskatchewan Cypress Hills, which are located directly east of the southeast Alberta Milk River-Lodge Creek drainage divide area.
  • The earlier east and northeast oriented melt water floods flowing across southeast Alberta represented ice-marginal melt water floods which flowed in a south direction west of rising Rocky Mountain ranges in western Alberta and eastern British Columbia and then south across western Montana where they were trapped by rising Rocky Mountain ranges to the south and southeast and were forced to flow in north and northeast directions toward the melting ice sheet surface, which by that time had become lower than the rising Rocky Mountain ranges. Ice sheet and the adjacent region bedrock surface lowering was being accomplished by development of huge ice-walled canyons, which were being carved into the ice sheet surface as giant supra-glacial melt water rivers flowed across the decaying ice sheet. Important to the southeast Alberta erosion history was an immense southeast and south oriented ice-walled canyon which extended across Saskatchewan, North Dakota, and South Dakota and which in time became an ice-walled and bedrock-floored canyon that detached the decaying ice sheet’s southwest wall. Today the northeast and east-facing Missouri Escarpment in Saskatchewan, North Dakota, and South Dakota is what remains of that immense ice-walled and bedrock-floor canyon’s southwest and west wall. East and northeast-oriented tributary valleys eroded headward from that ice-walled canyon into the surrounding bedrock surface to capture the massive south and southeast-oriented melt water floods, which were being trapped by the rising Rocky Mountain ranges in northern Wyoming and southwest Montana, and to initiate many of the north and northeast-oriented Missouri River tributary valleys seen today. The final major erosion event during the thick ice sheet’s rapid melt down consisted of headward erosion of a deep valley from the ice-walled and bedrock-floored canyon in the North Dakota northwest corner across the Montana Medicine Lake area to Poplar, Montana and then west along what is now the Missouri River valley. Closely following erosion of that deep valley was headward erosion of the deep Milk River tributary valley, which captured southeast-oriented ice-marginal flood waters moving between the Alberta Rocky Mountain front and the decaying ice sheet’s detached southwest margin. This essay addresses headward erosion of that Milk River valley and its tributary Lodge Creek valley.

Milk River-Lodge Creek drainage divide area

Figure 2: Milk River-Lodge Creek drainage divide area from Toporama 1:300,000 scale topographic map  .
  • Figure 2 represents a Toporama 1:300,000 scale topographic map illustrating the Southeast Alberta Milk River-Lodge Creek drainage divide area. The area where no data is available is located in Montana. Unfortunately at this scale Toporama topographic maps do not label most drainage routes although I will try to identify the important drainage systems. The high upland surface (with elevations exceeding 1400 meters) in the figure 2 northeast corner is the southeast Alberta Cypress Hills upland surface. Lodge Creek originates in a large north-south through valley crossing the west end of the Cypress Hills upland (the south end of which can be seen in the west half of map 72E9) and flows in a south-southeast direction into map 72E8 where it turns to flow in a southeast direction to the map 72E8 southeast corner and then to the figure 2 east edge. East and south of figure 2 Lodge Creek flows to join the Milk River in Montana. The Milk River is the east and southeast-oriented stream located in the deep valley seen in map 72E3 (note elevations in the Milk River valley are less than 900 meters). Pakowki Lake in maps 72E6 and 72E7 is labeled and easily identified and has an elevation of between 860 and 880 meters and today has no outlet, although should it ever overflow the water would flow in a north direction to eventually reach the northeast-oriented South Saskatchewan River. The stream flowing a northwest direction toward Pakowki Lake in the map 72E2 northeast quadrant is Canal Creek. The southeast-oriented stream on the northwest-oriented Canal Creek alignment and flowing across the map 72E1 southwest corner is Lost River, which like many streams in this essay  has an appropriate name in that it is discontinuous and ends (in this case in Montana to the southeast). Southeast-oriented streams east of Lost River in map 72E1 are tributaries to southeast-oriented Sage Creek which flows to the map 72E1 south edge east of center and ends in Wild Horse Lake just across the Montana border. The northwest-oriented stream flowing to Pakowki Lake north and east of Canal Creek is Ketchum Creek. South Manyberris Creek flows in a southwest and south-southwest direction just south of the town of Manyberries before turning to flow in a northwest direction adjacent to and parallel to Ketchum Creek. Note how South Manyberries Creek has a significant northwest-oriented tributary in the map 72E7 southeast quadrant which is on the same alignment as the southeast-oriented Sage Creek head waters. Manyberries Creek is the stream flowing to the Pakowki Lake north end just north of the town of Manyberries. These streams will be better labeled on more detailed topographic maps illustrated below. Before leaving figure 2 note the northwest-southeast oriented through valleys linking the northwest-oriented streams flowing to Lake Pakowki with the southeast-oriented stream flowing to Montana. These through valleys are former southeast-oriented melt water flood channels which cross the present day north-south continental divide.

Canal Creek-Sage Creek drainage divide area

Figure 3: Canal Creek-Sage Creek drainage divide area from Toporama 1:150,000 scale topographic map.
  • Figure 3 uses a Toporama 1:150,000 scale topographic map to illustrate the Canal Creek-Lost River drainage divide area seen in less detail in figure 2 above. The Canada-United States border is easily identified with no data available for areas in Montana. The southeast-oriented Milk River is labeled near the border and flows from the figure 3 west edge to the border and then for a short distance along the border toward the map 72E2 southeast corner before entering Montana. Southeast-oriented Lost River is also labeled and is located east of the Milk River and flows across the map 72E1 southwest corner before entering Montana. Southeast-oriented streams east of Lost River are Sage Creek tributaries, although most streams in this region appear to be intermittent and discontinuous especially once they enter Montana. The southeast-oriented stream just south of the town of Onefour (near west edge of map 72E1) is the Sage Creek tributary shown in more detail in figure 5. Canal Creek is also labeled and flows in a northwest direction from the Lost River headwaters area. Note how the northwest-oriented Canal Creek valley is aligned with both the southeast-oriented Lost River valley and the southeast-oriented Sage Creek tributary south of Onefour. Further note how southeast-oriented valleys are linked with the northwest-oriented Canal Creek valley by a large through valley. The map contour interval is 20 meters and a high area of over 1000 meters is located just east of the Milk River valley and a high area of over 980 meters is located just west of the Lost River valley. Other high areas of over 980 meters can be found between the unnamed Sage Creek tributary (south of Onefour) and the Sage Creek valley to the east and then east of the Sage Creek valley elevations rise in the figure 3 northeast corner. Elevations on the through valley floor at the drainage divide between Canal Creek and Lost River are between 940 and 960 meters suggesting this local through valley was at least 20 meters deep. The through valley between the Canal Creek valley and the unnamed Sage Creek tributary is different, but has a similar elevation. Figures 4 and 5 will look at each of these through valleys in detail, but remember these are local channels eroded into the floor of a much broader through valley defined by the areas higher than 1000 meters west of Lost River and east of Sage Creek. Proceeding west of the Milk River and the figure 3 map area and east of Sage Creek and the figure 3 map area elevations rise significantly higher so the Milk River, Lost River, unnamed southeast-oriented Sage Creek tributary, and Sage Creek valleys are all channels on the floor of a much broader and deeper valley. This large southeast-oriented valley was eroded by southeast-oriented melt water floods flowing to what at that time was the deep east-oriented Milk River valley which was eroding headward across north central Montana. Flood waters used multiple channels as is common in an anastomosing channel complex. Headward erosion of the deep northeast-oriented South Saskatchewan River valley and its tributary valleys beheaded the southeast-oriented flood flow routes using the Sage Creek, unnamed southeast-oriented Sage Creek tributary, and Lost River channels and flood waters on the northwest ends of those beheaded flood flow channels reversed flow direction to erode the northwest-oriented valleys.

Detailed map of Canal Creek-Lost River drainage divide area

Figure 4: Detailed map of Canal Creek-Lost River drainage divide area from Toporama 1:40,000 scale topographic map.
  • Figure 4 uses a 1:40,000 scale Toporama topographic map to illustrate the Canal Creek-Lost River drainage divide area seen in less detail in figures 2 and 3 above. Lost River is labeled and flows in a southeast direction to the figure 4 south edge (east half). While part of a discontinuous drainage system in Montana, water in Lost River if it should ever get to a continuous drainage system would flow to the Milk River and eventually end up in the Gulf of Mexico. Canal Creek is also labeled and flows in a northwest direction to the figure 4 north edge (west half). While Canal Creek is also part of a discontinuous drainage system today water in Canal Creek should it ever reach a continuous drainage system would flow to the South Saskatchewan River and eventually reach Hudson Bay. In other words the Canal Creek-Lost River drainage divide seen in figure 4 is North America’s north-south continental drainage divide. Note how the northwest-oriented Canal Creek valley is linked by a well-defined through valley with the southeast-oriented Lost River valley. Figure 4 elevations are given in feet and the map contour interval is 25 feet. The through valley floor elevation at the drainage divide is between 3000 and 3025 feet. Elevations immediately east of the through valley rise to more than 3100 feet while elevations immediately to the west rise to more than 3250 feet. In the figure 4 southwest corner elevations reach 3300 feet. Proceeding to the figure 4 northeast corner elevations east of Canal Creek rise and north and east of the figure 4 northeast corner rise to more than 3300 feet. While locally the through valley appears to be a relatively narrow channel about 100 feet deep it is actually a channel eroded into the floor of a much broader and deeper northwest-southeast oriented through valley, which is at least 200 feet deep based on figure 4 evidence (including evidence just north and east of the figure 4 northeast corner). As seen in figure 3 the through valley depth and width is probably much greater. As already mentioned the through valley was eroded by massive southeast-oriented melt water floods flowing to what was then the actively eroding east-oriented Milk River valley, which at that time was eroding headward across north central Montana. Headward erosion of the deep northeast-oriented South Saskatchewan River valley and its tributary valleys then beheaded southeast-oriented flood flow moving to the Lost River valley, but did not behead southeast-oriented flood flow further to the west on the present day southeast-oriented Milk River valley seen in figures 2 and 3. Flood waters on the northwest end of the beheaded flood flow channel reversed flow to erode the northwest-oriented Canal Creek valley. Flood waters on the southeast-oriented Milk River valley to the west were not beheaded and were able to erode a deeper valley, which continued erode headward across southern Alberta slightly ahead of South Saskatchewan River valley and tributary valley headward erosion.

Detailed map of Canal Creek-Sage Creek tributary drainage divide area

Figure 5: Detailed map of Canal Creek-Sage Creek tributary drainage divide area from Toporama 1:40,000 scale topographic map .
  • Figure 5 uses a Toporama 1:40,000 scale topographic map to illustrate the Canal Creek-Sage Creek tributary drainage divide area located east of the figure 4 map area (and includes overlap areas with figure 4). Canal Creek is labeled and flows in a southeast, west, and northwest direction toward the figure 5 northwest corner. As seen in earlier figures Canal Creek flows to Lake Pakowki, which is today an internal drainage basin. However, if Lake Pakowki should ever overflow the water would eventually reach the South Saskatchewan River and finally end up in Hudson Bay. The southeast-oriented streams flowing to the figure 5 south edge, south of the town of Onefour, is a Sage Creek tributary with water today ending up in Wild Horse Lake just across the United States border in Montana. Wild Horse Lake is also today an internal drainage basin, but should it ever overflow the water would flow to the Milk River and eventually reach the Gulf of Mexico. The Canal Creek-Sage Creek tributary drainage divide seen in figure 5 is a continuation of the north-south continental divide seen in earlier figures. Note the through valley linking the northwest-oriented Canal Creek valley with the southeast-oriented Sage Creek tributary valley. Again figure 5 elevations are given in feet and the contour interval is 25 feet. The through valley floor elevation at the drainage divide is between 3050 and 3075 feet. Elevations greater than 3125 feet are found just to the west and elevations greater than 3250 feet are found to the east. Remember from figure 4 that elevations west of the Lost River in figure 4 rise to 3300 feet.  Again what looks like a relatively shallow and narrow channel is in fact just one of several such channels eroded into the floor of a much broader and deeper northwest-southeast oriented through valley. The much larger through valley was as already described eroded by massive southeast-oriented melt water flood flow moving to the what at that time was the actively eroding and deep Milk River valley in north central Montana. Flood flow in the northeast section of this large southeast-oriented valley was beheaded by headward erosion of the northeast-oriented South Saskatchewan River valley and its tributary valleys. Flood waters on the northwest end of the beheaded flow channel reversed flow direction and eroded the northwest-oriented Canal Creek valley, which also eroded headward in an east direction to capture south and southeast-oriented flood flow further to the east as seen along the figure 5 north edge.

South Manyberries Creek-Sage Creek drainage divide area

Figure 6: South Manyberries Creek-Sage Creek drainage divide area from Toporama 1:150,000 scale topographic map.
  • Figure 6 uses a Toprama 1:150,000 scale topographic map to illustrate the South Manyberries Creek-Sage Creek drainage divide area north and east of the figure 3 map area and includes overlap areas with figure 3. Sage Creek is labeled and flows in a south-southeast direction across the map 72E8 southwest corner into map 72E1 and to the figure 6 south edge (near southeast corner). Cripple Creek is a southeast and east-oriented tributary joining Sage Creek in map 72E1. As previously described Sage Creek flows to Wild Horse Lake in Montana, which does not have an outlet today. However should Wild Horse Lake ever overflow the water would go to the Milk River and eventually reach the Gulf of Mexico. Ketchum Creek is a labeled west-northwest and northwest oriented stream in the south half of map 72E7 and west of the figure 6 map area flows to Lake Pakowki. South Manyberries Creek flows in a southwest direction from the figure 6 north edge (west of center and east of the town of Manyberries) toward Ketchum Creek and then turns to flow in northwest direction parallel to and adjacent to Ketchum Creek and also flows to Lake Pakowki. A major northwest oriented South Manyberries Creek tributary (also labeled South Manyberries Creek) is located north of Ketchum Creek in map 72E7. North and west of South Manyberries Creek is Manyberries Creek (north of the town of Manyberries) which also flows to Lake Pakowki. Also as mentioned previously Lake Pakowki does not normally have an outlet although if it should overflow the water would eventually reach the South Saskatchewan River and end up in Hudson Bay. Note the northwest-southeast oriented through valley linking the northwest-oriented South Manyberries Creek tributary valley with the southeast-oriented Sage Creek valley (the railroad line is located in the through valley). Near the map 72E7 southeast corner another shallower through valley links the northwest-oriented Ketchum Creek valley with the southeast-oriented Cripple Creek valley. Just to the southwest is another shallow northwest-southeast oriented through valley linking the northwest Ketchum Creek valley with the valleys of south- and southeast-oriented headwaters tributaries flowing to the northwest-oriented Canal Creek in map 72E2. These northwest-southeast oriented through valleys are additional channels eroded into the floor of a much broader and deeper northwest-southeast oriented through valley. Note how elevations rise toward the figure 6 northeast corner and are greater than 1200 meters. South and west of the southeast-oriented Milk River valley seen in figures 2 and 3 (in northern Montana) are the Sweet Grass Hills, a Rocky Mountain outlier, with buttes higher than 2000 meters. Evidence  presented in the Milk River-Marias River drainage divide area landform origins, Sweet Grass Hills, Toole and Hill Counties, Montana essay suggests at one time south and southeast-oriented melt water floods crossed what are today high ridges in the Sweet Grass Hills, suggesting more than 1000 meters of bedrock material may have been removed from the figure 6 map area to create the landscape seen today.

Detailed map of South Manyberries Creek-Sage Creek drainage divide area

Figure 7: Detailed map of South Manyberries Creek-Sage Creek drainage divide area from Toporama 1:40,000 scale topographic map.
  • Figure 7 uses a Toporama 1:40,000 scale topographic map to illustrate the South Manyberries Creek northwest-oriented tributary-Sage Creek drainage divide area seen in less detail in figure 6 above. The northwest-oriented South Manyberries Creek tributary is labeled as South Manyberries Creek and flows to the figure 7 west edge (near northwest corner). Sage Creek is also labeled and flows in a south-southwest and south direction from the figure 7 east edge (south of center) to the figure 7 south edge (west of southeast corner). A south-southeast oriented Sage Creek tributary drains the southeast end of a through valley linking the South Manyberries Creek valley with the Sage Creek valley and joins Sage Creek just south of the figure 7 map area. The figure 7 map elevations are again in feet and the contour interval is 25 feet. The through valley floor elevation at the drainage divide is between 3175 and 3200 feet. Elevations in the figure 7 northeast corner area rise to more than 3500 feet. Elevations west of the through valley seen near the figure 7 west edge rise to more than 3475 feet and in one location exceed 3500 feet. These elevations indicate the through valley is at least 300 feet deep and as seen in earlier figures this is just a channel eroded into the floor of a much broader and deeper northwest-southeast oriented through valley. The through valley seen in figure 7 was eroded by massive southeast-oriented melt water flood flow moving to what at that time was the actively eroding and deep Milk River valley (in Montana). Southeast-oriented flood flow to the Milk River valley was beheaded by headward erosion of the deep northeast-oriented South Saskatchewan River valley and its deep northeast-oriented tributary valleys. Flood waters on the northwest end of the beheaded flood flow channel reversed flow direction to erode the northwest-oriented South Manyberries Creek valley and to create the South Manyberries Creek-Sage Creek drainage divide seen in figure 7.

Chin Coulee-Pakowki Lake drainage divide area

Figure 8: Chin Coulee-Pakowki Lake drainage divide area from Toporama 1:300,000 scale topographic map.
  • Figure 8 uses a 1:300,000 scale topographic map to illustrate the Chin Coulee-Pakowki Lake drainage divide area west and north of the figure 3 map area and includes overlap areas with figure 3. The Milk River flows in an east direction across map 72E3 and into map 72E2 where it crosses the figure 8 south edge before turning to flow in a southeast direction into Montana. Pakowki Lake is labeled and has east and southeast-oriented inlets from the west and northwest and southwest-oriented inlets from the east. The long east and southeast-oriented stream flowing from map 72E5 to Pakowki Lake is Etzikom Coulee which will be seen in more detail in figure 9 below. Ketchum Creek is the northwest-oriented inlet flowing the from southeast corner of map 72E7 and South Manyberries Creek is north of Ketchum Creek with Manyberries Creek being the stream just north of the town of Manyberries. The east-oriented stream flowing from the south margin of map 72E12 into map 72E11 and then turning to drain in a northeast and north direction is Chin Coulee, which connects with a continuous drainage route to the northeast-oriented South Saskatchewan River. Note how Lake Pakowki has no outlet shown, although through valleys connect it to the Milk River valley to the south and with the Chin Coulee valley to the north. Through valleys linking the Lake Pakowki basin with the Milk River valley are shown as having floor elevations of between 880 and 900 meters. The much broader through valley linking the Lake Pakowki basin with the Chin Coulee valley has a floor elevation of between 860 and 880 meters and is slightly lower than the through valleys to the Milk River valley. The Milk River through valleys suggest headward erosion of a major north and northeast-oriented South Saskatchewan River tributary valley across the massive east- and southeast-oriented melt water flood flow route almost captured flood flow moving in the Milk River valley, but apparently flood flow in the region ended just before the capture was accomplished. Another possibility is headward erosion of the deep Milk River valley channel captured east-oriented melt water flood flow moving toward the actively eroding Chin Coulee valley. Why the Lake Pakowki basin is today an internal drainage basin is difficult to determine from the map evidence alone. Evidence in the Sweet Grass Hills region suggests crustal warping continued during and possibly after the flood flow that eroded that region (south of the figure 8 southwest quadrant). If so minor crustal warping could have helped form the Lake Pakowki internal drainage basin although other possibilities exist.

Chin Coulee-Etzikem Coulee drainage divide area

Figure 9: Chin Coulee-Etzikem Coulee drainage divide area from Toporama 1:150,000 scale topographic map.
  • Figure 9 is a Toporama 1:150,000 scale topographic map illustrating the Chin Coulee-Etzikom Coulee drainage divide area seen in less detail in figure 8 above. Chin Coulee is labeled and drains in an east, northeast, and north direction in map 72E11. Etzikom Coulee is also labeled and drains in an east-northeast and east-southeast direction in map 72E6 to Lake Pakowki (which is not labeled, but which is located in the figure 9 southeast quadrant). The map contour interval is 20 meters and the Lake Pakowki surface elevation appears to be between 860 and 880 meters, although labeling on some contour lines is confusing. A shallow but broad north-oriented through valley extends from Lake Pakowki through the northwest corner of map 72E7 along the west margin of map 72E10 to northwest and north-oriented Peigan Creek, which joins Chin Coulee near the figure 9 north edge. This valley was eroded headward from what was at that time the actively eroding South Saskatchewan River valley to capture east- and southeast-oriented melt water flood flow south of the southeast-oriented Forty Mile Coulee and east-oriented Chin Coulee flood flow routes seen in map 72E11. The Forty Mile Coulee and Chin Coulee valleys eroded headward from this north-oriented valley and subsequently headward erosion of the east- and southeast-oriented Etzikom Coulee valley was from this north-oriented valley. As previously mentioned either this north-oriented valley continued to erode headward so as to almost capture the east-oriented flood flow on the Milk River alignment to the south or the Milk River valley eroded headward from this north-oriented valley and subsequently was captured by headward erosion of the southeast-oriented Milk River valley from Montana. In either case there was a time when flood waters moving in the east-oriented Milk River valley (seen in figure 8) were being split with some flood waters flowing to the north-oriented valley to the developing northeast-oriented South Saskatchewan River valley and some of the flood waters flowing to the southeast-oriented Milk River valley and into Montana. At that time the Milk River-Missouri River valley was moving flood waters to a giant ice-walled and bedrock-floored canyon located in the North Dakota northwest corner and the developing South Saskatchewan River valley was also moving flood waters to giant ice-walled and bedrock-floored canyons. Water in these ice-walled and bedrock-floored canyons by that time had ceased to flow in south directions and was instead flowing in the giant ice-walled and bedrock-floored canyons across the  decaying ice sheet floor to the present day Saint Lawrence River drainage basin and/or to the Hudson Bay region. This diversion of immense south-oriented melt water floods from the Gulf of Mexico to the North Atlantic was what ended the ice sheet’s rapid melt down, which also ended the immense ice-marginal floods and erosion of the Milk River-Lodge Creek drainage divide area.

Detailed map of Chin Coulee-Seven Persons Creek drainage area

Figure 10: Detailed map of Chin Coulee-Seven Persons Creek drainage area from Toporama 1:150,000 scale topographic map.
  • Figure 10 uses a 1:150,000 scale topographic map to illustrate the Chin Coulee-Seven Persons Creek drainage area north of the figure 9 map area and includes overlap areas with figure 9. Chin Coulee drains in an east direction from the figure 10 southwest corner region and then turns to drain in a north direction to the map 72E14 southeast corner where it joins east-oriented Seven Persons Creek, which flows to Murray Lake in the southwest corner of map 72E15. From Murray Lake Seven Persons Creek flows in a north-northeast direction to Seven Persons Lake, in the figure 10 northeast corner region, and then flows to join the northeast-oriented South Saskatchewan River (see figure 1). Note how in the figure 10 southeast corner region in map 72E10 elevations east of the north-oriented Chin Coulee valley are significantly higher than the Chin Coulee valley floor. Bulls Head is shown as having an elevation of 1083 meters while to the west the Chin Coulee valley floor has an elevation of less than 800 meters. There is no evidence in figure 10 (or figure 8) that the west wall of the deep north-oriented Chin Coulee valley still exists. The evidence suggests southeast-oriented flood flow, which was captured by headward erosion of the east-oriented Milk River valley, Etzikom Coulee valley, Chin Coulee, and valleys completely removed the west wall of what at one time may have been a 200-300 meter deep north-oriented valley. If so we are seeing evidence for removal of at least 200-300 meters of material from much southeast and south central Alberta by the massive ice-marginal melt water flood flow and also by headward erosion of the deep northeast-oriented South Saskatchewan River valley and its tributary valleys. It is possible some of this removed material was decaying ice into which the northeast-oriented South Saskatchewan River valley and its tributary valleys eroded headward, although the figure 10 evidence suggests considerable bedrock material was also removed.

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 libraries located throughout Canada and elsewhere.

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