Wood River-Frenchman River drainage divide area landform origins, southern Saskatchewan, Canada

Abstract:

Topographic map interpretation methods are used to determine landform origins along the Wood River-Frenchman River drainage divide area in southern Saskatchewan, Canada. The Wood River-Frenchman River drainage divide is located along the west end of the Wood Mountain upland region just north of the Saskatchewan-Montana border. Today the Wood River flows in a north-direction to Old Wives Lake, which is located in a closed basin with no outlet stream. The Frenchman River flows in a southeast and south direction to join the Milk River in Montana, with the Milk River then flowing to the east and southeast-oriented Missouri River. The Wood River-Frenchman River drainage divide is today crossed by multiple north-south oriented through valleys of varying depth, which link north-oriented Wood River tributary valleys with south-oriented Frenchman River tributary valleys. These through valleys provide evidence the present day drainage divide was at one time eroded by an immense south-oriented anastomosing channel complex supplying flood waters to what were then actively eroding south-oriented Frenchman River tributary valleys. At that time elevations north of the present day drainage divide were at least as high, if not higher, than the present day drainage divide elevation. Headward erosion of deep valleys north of the present day then beheaded the south-oriented flood flow channels in sequence from east to west. Flood waters on north ends of beheaded flood flow channels reversed flow direction to erode north-oriented valleys and to capture south-oriented flood water from flood flow channels further to the west. Such flood flow captures eroded east-oriented valleys along the drainage divide north flank and supplied water volumes required to erode significant north-oriented valleys. Flood waters were derived from a rapidly melting North American ice sheet located north of the study region.

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

Wood River-Frenchman River drainage divide area location map

Figure 1: Wood River-Frenchman River 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 the more detailed grid identifies 1:50,000 topographic map sheets.

Figure 1 provides a location map for the Wood River-Frenchman River drainage divide area in southern Saskatchewan and illustrates a section of a Natural Resources Canada index map for southern Saskatchewan topographic maps. The large grid identifies numbers for 1:250,000 topographic map sheets and the more detailed grid identifies numbers for 1:50,000 topographic map sheets. Map numbers will be used throughout this essay to identify locations. Areas south of the index map grid are located in Montana. The north end of the Fort Peck Reservoir can be seen along the figure 1 south center edge and east of the Fort Peck Reservoir the Missouri River flows in an east direction along the figure 1 south edge. The unlabeled southeast, east-northeast, and southeast drainage route flowing from the figure 1 west edge (south half) to join the Missouri River immediately downstream from the Fort Peck reservoir is the Milk River. The east, southeast, and south oriented tributary flowing from map 72F across the southwest corner of map 72G to join the Milk River is the Frenchman River and is labeled. Note south and south-southwest oriented Frenchman River tributaries originating in maps 72G2 and 72G3. Between the Frenchman River and Poplar River headwaters are south-oriented headwaters of Rock Creek, including Morgan Creek, which flows directly to the Milk River. North of those south-oriented tributary headwaters are east-southeast oriented headwaters of the north-northeast oriented Wood River (unlabeled on figure 1), which flows to Old Wives Lake.

The Wood River-Frenchman River drainage divide area addressed here is located in maps 72G2, 72G3, 72G6, and 72G7 and is a high drainage divide located on the west end of the Wood Mountain upland. Southeast and south-oriented streams originating in maps 72G1, 72H4, and 72H5 are headwaters of the Poplar River, which flows to the Missouri River in figure 1. The Wood River-Poplar River drainage divide landform origins , southern Saskatchewan essay illustrates and describes evidence in that region, which includes the Wood Mountain upland eastern end. South-oriented streams originating in maps 72H2 and 72H3 are headwaters of Big Muddy Creek, which also joins the Missouri River. The South Saskatchewan River-Big Muddy Creek drainage divide area landform origins, southern Saskatchewan essay illustrates and describes a large through valley extending in a north-northwest direction from the Big Muddy Creek valley to Old Wives Lake and then to the South Saskatchewan River (which can be seen flowing in an east and northeast direction along the figure 1 north center edge). These two essays can be found under Saskatchewan on the sidebar category list. The Poplar River-Big Muddy Creek drainage divide area landform origins northeast Montana essay illustrates and describes areas between those two drainage routes in Montana. This latter essay can be found under MT Missouri River on the sidebar category list.

Before looking at the study region in detail a brief discussion of the Wood River-Frenchman River drainage divide position in a big picture context might be helpful. Erosion events described in this essay occurred late during the melt down history of a thick North American ice sheet. I use the term “thick” to indicate the ice sheet had been comparable in thickness to the present day Antarctic Ice Sheet, which is several kilometers in thickness. This thick North American ice sheet had been located in a deep “hole” which had been formed by a combination of crustal warping caused by the ice sheet’s great weight and of deep glacial erosion of bedrock underneath the massive ice sheet. The Wood Mountain region in southern Saskatchewan was located along the deep “hole’s” southwest margin with the Canadian Shield region representing the area where glacial erosion was greatest.

Uplift of Rocky Mountain and Rocky Mountain outlier ranges to the south and west of the Wood Mountain region was probably the result ice sheet caused crustal warping, although deep melt water flood erosion and deposition of flood transported debris may also have played a significant role in the development of at least some of the Rocky Mountain crustal warping. The ice sheet had been formed on a topographic surface corresponding to the highest Rocky Mountain topographic surfaces today, if not on an even higher topographic surface which was subsequently completely destroyed by deep melt water flood erosion. Initially giant melt water rivers from the melting ice sheet flowed in south and southeast directions along the ice sheet’s southwest margin and then across the present day Rocky Mountains on a route now occupied by high Rocky Mountain ranges to eventually reach the Gulf of Mexico.

Other major south oriented flood flow routes developed east of the Wood Mountain region (in the center of the continent) with flood waters eroding the south oriented Mississippi River valley. In time headward erosion of the deep Mississippi River valley and its east and southeast-oriented tributary valleys combined with Rocky Mountain uplift, which was occurring as flood waters flowed across region, dismembered the south and southeast-oriented flood flow routes through the Rocky Mountains. The Rocky Mountain flood flow routes were dismembered from south to north. For example in Colorado headward erosion of the Arkansas River valley captured the south and southeast-oriented flood flow first. South Platte River valley headward erosion captured the south- and southeast-oriented flood flow next. North Platte River valley headward erosion, probably aided by major Rocky Mountain uplift, next beheaded and reversed the south- and southeast-oriented flood flow.

In time, instead of standing high above the surrounding region, the ice sheet surface at least in places was at approximately the same level as the surrounding regions. Further, immense southeast and south-oriented melt water rivers flowing across the ice-sheet surface began to carve giant ice-walled (and later bedrock-floored) canyons into the rapidly melting ice sheet surface. One such ice-walled and bedrock-floored canyon was north and east of the Wood Mountain region and extended from east central Alberta in southeast direction across southeast Saskatchewan into North Dakota. In central North Dakota this ice-walled and bedrock-floored canyon split with one branch continuing in a southeast direction while the other branch extended in a south direction to southeast South Dakota. The immense melt water river flowing on the floor of the western branch of this ice-walled and bedrock-floored canyon emerged from the ice sheet south margin in southeast South Dakota and was responsible for eroding the large Missouri River valley headward to that area. The eastern branch drained to what is now the Mississippi River valley.

The Missouri Escarpment is today what remains of the southwest and west wall of this giant southeast and south oriented ice-walled and bedrock-floored canyon. As the ice-walled and bedrock-floored canyon was being carved its floor was lower in elevation than areas along the ice sheet’s southwest margin and the giant canyon eventually detached the ice sheet’s southwest margin. The ice sheet’s southwest margin (which eventually was detached) provided a barrier between immense southeast-oriented ice-marginal melt water floods and the lower elevation ice-walled canyon floor to the northeast. However, breaches in the ice sheet’s southwest margin did open up and such breaches frequently resulted in the headward erosion of deep northeast-oriented valleys, which captured significant percentages of the southeast-oriented ice marginal melt water flood flow. Yellowstone River valley headward erosion, which was followed by Missouri River valley headward erosion across northern Montana, was initiated by headward erosion of a deep valley from such ice sheet margin breach, although there may have been earlier breaches at higher elevations as the ice sheet surface and surrounding region landscape elevations were lowered. Headward erosion of the east and southeast oriented Milk River valley (from the actively eroding Missouri River valley) captured some flood flow routes to the newly eroded Missouri River valley while headward erosion of the Frenchman River valley (from the actively eroding Milk River valley) next captured some of the flood flow routes to the actively eroding Milk River valley. As the south- and southeast-oriented flood flow routes through the Rocky Mountains were being dismembered by headward erosion of Mississippi River tributary valleys aided by Rocky Mountain uplift the ice sheet surface was also being lowered and these large northeast-oriented valleys began to eroded headward from the ice sheet’s southwest margin.

In time the ice-walled and bedrock-floored valleys being carved by melt water rivers into the decaying ice sheet surface opened up new melt water flood flow routes to the North Atlantic Ocean and to what is now Hudson Bay. These new east and north-oriented flow routes captured the immense south and southeast-oriented melt water rivers flowing on the floors of the ice-walled and bedrock-floored canyons and diverted the melt water flood flow in a north direction. The decreases in melt water flood flow moving to the Gulf of Mexico combined with the increase in melt water flood flow to the north significantly changed Atlantic Ocean circulation patterns, which in turn significantly altered Northern Hemisphere climates. The climate, which had been conducive to rapid ice sheet melting, was replaced by a climate conducive to ice sheet formation and the north-oriented flood water began to freeze on the floors of the ice-walled and bedrock-floored canyons. The result was a thin ice sheet with remnants of the former thick ice sheet embedded in it. This new thin ice sheet blocked many of the breaches through which the ice marginal melt water floods were flowing onto the deeper ice sheet floor, which resulted in capture of the newly developed northeast-oriented drainage systems by the evolving ice-marginal Missouri River valley (in North Dakota and northeast Montana).

While this history has been very brief it provides the context for events in the Wood River-Frenchman River drainage divide area investigated in this essay. Events described in this essay occurred at a time when the ice sheet surface and surrounding region surface had already been significantly lowered by ice sheet melting and melt water erosion and the deep Missouri River valley was being eroded headward from a major breach in the detached ice sheet margin. It is possible the breach migrated in a southeast direction as the regional surface (including the ice sheet surface) was lowered. Initially the breach may have been in the present day Cypress Hills area and alluvium capping the Cypress Hills was deposited by an immense east and/or northeast-oriented rivers flowing onto the ice sheet surface. As the regional surface (and ice sheet surface) was lowered the breach and east and/or northeast-oriented rivers may have migrated to the Wood Mountain area and alluvium capping the Wood Mountain upland may have been deposited where the rivers flowed onto the ice sheet surface. The Flaxville surface in northeast Montana may have been next breach location and finally what is now a large northeast-oriented valley in northeast Montana and the North Dakota northwest corner may have been the breach and river location at the time events described in this essay took place.

[For readers unfamiliar with the Cypress Hills, Wood Mountain, and Flaxville alluvium and fossils, which are not mentioned in this essay, you need to be aware vertebrate paleontologists have proposed a fundamentally different geologic history than the erosional history suggested above. In brief vertebrate paleontology interpretations require the sediments to have been deposited over a period of approximately 30 million years prior to continental glaciation as erosion slowly lowered the regional landscape. This geologic history implies little or no glacial and/or melt water flood water erosion of the region, which is fundamentally different from the deep glacial and melt water flood erosion proposed in this and in other Missouri River drainage basin landform origins research project essays. The presence of vertebrate fossils and sedimentary deposits does not preclude the erosional history presented here, although the fossils and sediments need to be interpreted in completely different ways than vertebrate paleontologists have been interpreted them to date.]

Big picture topographic map for Wood River-Frenchman River drainage divide area

Figure 2: Big picture topographic map for Wood River-Frenchman River drainage divide area from Toporama 1:300,000 scale map.

Figure 2 provides a big picture topographic map of the Wood River-Frenchman River and Wood River-Poplar River drainage divide areas at Wood Mountain in southern Saskatchewan. South and southeast oriented drainage routes in map 72G1 are headwaters of the southeast and south oriented Poplar River, which flows to the Missouri River in Montana (south of the figure 2 map area). The West Poplar River is the south and south-southeast oriented Poplar River tributary located near the west edge of the map 72G1 northwest quadrant. South and southwest-oriented drainage routes in map 72G2 flow to south oriented Rock Creek and the southeast and south oriented Frenchman River (south of figure 2), which flow to the southeast-oriented Milk River, which in turn flows to the Missouri River. Morgan Creek is a south-oriented Rock Creek tributary flowing near the map 72G2 east edge. The Wood River flows in an east-southeast direction from map 72G6 into map 72G7 and then flows in a north-northeast direction into map 72G10, and then to the figure 2 north edge. All north-oriented drainage routes in figure 2 are Wood River tributaries. The west-east oriented drainage divide between the north-oriented Wood River drainage and the south-oriented Frenchman River drainage roughly follows the line between maps 72G7 and 72G2 and is the west end of the Wood Mountain upland region. Note how Wood Mountain elevations reach 1000 meters near the map 72G7 south center border. Proceeding north in the Wood River valley to map 72G10 elevations fall to approximately 740 meters. In other words the Wood Mountain upland stands roughly 250 meters higher than the plains to the north.

Elevations in the map 72G2 southwest corner fall to less than 800 meters and are even lower south and west of the figure 2 map area, so Wood Mountain can be considered to be standing at least 250 meters higher than the surrounding plains in most if not all directions and appears to be an erosional remnant, probably preserved due to some type of erosion resistant material. Using only topographic evidence we cannot determine what erosion resistant material caps the Wood Mountain upland, but we can observe how the upland was eroded. While figure 2 detail is very limited we can see through valleys eroded across the drainage divide. Perhaps the easiest through valley to observe is located in the map 72G2 northwest quadrant and links a north-oriented Wood River tributary valley with a south-oriented Frenchman River tributary valley and appears to be 80 meters or more deep. Other shallower through valleys can be seen crossing the drainage divide at other locations. The through valleys provide evidence the Wood Mountain upland was crossed by multiple south-oriented flood flow channels, such as might be found in a large-scale anastomosing channel complex.

The most likely source of the south oriented flood water would be a rapidly melting ice sheet located north of the drainage divide. Further, to reach and cross the Wood Mountain upland the south oriented flood flow would have to have flowed on a topographic surface at least as high as the present day Wood Mountain upland. If so, something must have happened to cause the flood waters to reverse flow direction and to deeply erode the north-oriented Wood River drainage basin and the region north of the Wood Mountain upland. East of the figure 2 map area is the deep south-oriented Big Muddy Creek valley, which is today linked by a large south- and southeast-oriented through valley with the Old Wives Lake basin. Today the Old Wives Lake basin is a closed basin with no outlet and is also where the Wood River flows. The South Saskatchewan River-Big Muddy Creek drainage divide area landform origins in southern Saskatchewan and the Wood River-Poplar River drainage divide area landform origins in southern Saskatchewan essays discuss how headward erosion of the deep Big Muddy Creek valley (and the northern through valley extension) captured southeast-oriented flood flow north of the Wood Mountain upland and caused flood flow reversals that eroded the Wood Mountain northern flank and also eroded the north-northeast oriented Wood River valley.

Tetrau Creek-Dunn Creek drainage divide area

Figure 3: Tetrau Creek-Dunn Creek drainage divide area from Toporama 1:40,000 map.

Figure 3 provides a more detailed topographic map of the Wood River-Frenchman River drainage divide in the region between maps 72G7 and 72G2. All north oriented streams in map 72G7 eventually reach the north-oriented Wood River. The south and south-southeast oriented West Poplar River can be seen flowing to the figure 3 southeast corner and is a Poplar River tributary. West of the West Poplar River in map 72G2 is south-oriented Wetherall Creek, which eventually reaches the Frenchman River. Between Wetherall Creek and the West Poplar River are south-oriented Rock Creek headwaters, with Rock Creek flowing directly to the Milk River. Note how Morgan Creek headwaters are located on the Wood Mountain upland surface and are linked by shallow through valleys with north-oriented Ten Mile and Nine Mile Creeks. The through valleys are only defined by a single 20-meter contour line and are subtle features, but they exist. Proceeding west are Hellfire Creek and West Hellfire Creek, which also are linked by shallow through valleys with north-oriented Wood River tributary valleys. Next is Wetherall Creek, which is linked by a deeper through valley with north-oriented McCrea Creek. Through valleys identified so far provide evidence multiple south-oriented flood flow channels crossed what are today some of the highest elevations in the Wood Mountain upland region, although also provide evidence the flood water erosion was not deep. Continuing west to south-oriented Horse Creek and Dunn Creek we find they are linked by even deeper through valleys with north-oriented Tetrau Creek. Floors of these north-northeast oriented through valleys are less than 900 meters while elevations along the drainage divide to the east rise to more than 1000 meters and to the west rise to more than 980 meters. Between these two deep through valleys is a shallower through valley linking unnamed north- and south-oriented tributary valleys. As previously mentioned the multiple through valleys provide evidence of multiple south-oriented oriented flood flow channels, which were flowing to actively eroding south-oriented valleys, which were carving the Wood Mountain upland south flank. The Wood River-Frenchman River drainage divide in figure 3 was created as headward erosion of the deep east and southeast oriented tributary valleys from the deep southeast and south oriented Big Muddy Creek valley (east of the study region) beheaded and reversed the south-oriented flood flow channels in sequence from east to west. Flood flow channels were beheaded and reversed one at a time, which meant newly reversed flood flow channels could capture south-oriented flood flow from flood flow channels further to the west. Such captures of yet to be beheaded flood flow provided water volumes required to erode significant north-oriented valleys and also to create northeast-oriented flood flow routes, which then eroded northeast-oriented valleys (see Tetrau Creek valley). This process will be further explained in subsequent figures.

Detailed map of Tetrau Creek-Horse Creek drainage divide area

Figure 4: Detailed map of Tetrau Creek-Horse Creek drainage divide area from Toporama 1:40,000 scale map.

Figure 4 provides a detailed topographic map of the Tetrau Creek-Horse Creek drainage divide area and also of the McCrea Creek-Wetherall Creek drainage divide area seen in less detail in figure 3 above. Horse Creek flows in a south direction to the figure 4 south center edge with water eventually reaching the Frenchman River. Wetherall Creek (unlabeled in figure 4) flows in a south direction near the figure 4 east edge and water also eventually reaches the Frenchman River. McCrea Creek is the north-oriented stream in the figure 4 northeast corner and water flows to the north-oriented Wood River. The unlabeled northwest and west oriented stream in the figure 4 northwest quadrant flows to north-oriented Tetrau Creek, which in turn flows to the Wood River. Map 72G2 has a contour interval of 25 feet and the relatively flat upland surface in the figure 4 east center area has an elevation of slightly more than 3250 feet. Note the through valley linking the north-oriented McCrea Creek valley with the south oriented Wetherall Creek valley. The drainage divide between the two opposing streams is actually north of the highest Wood Mountain upland area and has an elevation of between 3100 and 3125 feet. In other words, the through valley eroded across the Wood Mountain upland region has a depth of at least 125 feet. Further west note how a south-southwest oriented Horse Creek tributary has northwest-oriented tributaries on the west side of large flat-topped Wood Mountain area. The northwest-oriented tributary valleys were eroded by reversals of south- and southeast-oriented flood flow routes as the deep south-southwest oriented Horse Creek valley eroded headward into the region. These tributary valleys provide evidence that large volumes of water were present in the region as the south-oriented Horse Creek valley was being eroded. Note how some of the northwest-oriented tributary valleys can be linked by shallow through valleys with south-oriented streams located south of the flat-topped Wood Mountain upland mass. Further note how the Horse Creek headwaters are located near the figure 4 north center edge and eroded valleys which beheaded south-oriented flood flow routes to what was once an actively eroding south-southwest oriented Horse Creek tributary valley. Through valleys linking the northwest-oriented Tetrau Creek tributary valley with the south-oriented Horse Creek valley can be seen in the figure 4 west center and northwest quadrant areas. The drainage divide in the deepest through valley in the figure 4 west center area has an elevation of between 2875 and 2900 feet. As already noted elevations of the flat-topped Wood Mountain upland region in the figure 4 east center area rise to more than 3250 feet. While elevations west of Horse Creek are lower a small region where elevations exceed 3200 feet can be found in the figure 4 southwest quadrant. In other words, the Tetrau Creek-Horse Creek through valley has a depth of at least 300 feet and was eroded as a large south-oriented flood flow channel.

Detailed map of Tetrau Creek-Dunn Creek drainage divide area

Figure 5: Detailed map of Tetrau Creek-Dunn Creek drainage divide area from Toporama 1:40,000 scale map.

Figure 5 provides a detailed topographic map of the Tetrau Creek-Dunn Creek drainage divide area west of the figure 4 map area and includes overlap areas with figure 4 (and was also seen in less detail in figure 3). North of the figure 5 map area Tetrau Creek flows to the Wood River. Tetrau Creek is labeled and flows in an east direction from the figure 5 west center edge before turning to flow in a north-northeast and north direction to the figure 5 north edge (just west of center). Note the large northwest-oriented Tetrau Creek tributary seen in figure 4. Dunn Creek is the south-oriented stream south of the Tetrau Creek elbow of capture (where Tetrau Creek turns from flowing in an east direction to flowing in a north-northeast direction). Other south-oriented streams in the figure 5 southwest quadrant are Dunn Creek tributaries. Water in Dunn Creek eventually reaches the Frenchman River. The south-oriented stream near the figure 5 east edge is Horse Creek, which was also seen in figure 4. Note how south of the Tetrau Creek elbow of capture a deep north-south oriented through valley links the north-oriented Tetrau Creek valley with the south-oriented Dunn Creek valley. The map 72G2 contour interval is 25 feet and the through valley floor elevation is between 2900 and 2925 feet. Elevations greater than 3175 feet can be found on either side of the through valley meaning the through valley is at least 250 feet deep. Remember the Tetrau Creek-Horse Creek through valley described in figure 4 and seen in the figure 5 east center region had a valley floor elevation of between 2875 and 2900 feet, which is slightly deeper than the Tetrau Creek-Dunn Creek through valley. However, the south-oriented flood waters that eroded one of the through valleys also eroded the other through valley. The two different through valleys provide evidence of what were once two diverging south-oriented flood flow channels being eroded into the Wood Mountain upland surface. Such divergence of flood flow channels is common in flood formed anastomosing channel complexes and the presence of diverging through valleys provides evidence the Wood Mountain upland surface was eroded by an immense south-oriented anastomosing channel complex. Many other shallower through valleys can also be seen in the figures 4 and 5 map areas providing evidence of still other diverging and converging flood flow channels. South-oriented flood flow channels across the figures 4 and 5 map areas were beheaded and reversed in sequence from east to west by deep east and southeast-oriented valleys (north of the study region) eroding headward from the deep south-oriented Big Muddy Creek valley (east of the study region). The east-oriented Tetrau Creek valley was eroded when yet to be beheaded south-oriented flood flow routes west of the newly beheaded and reversed Tetrau Creek-Dunn Creek flood flow channel were captured and water flowed in an east direction to the newly reversed Tetrau Creek valley.

Tetrau Creek-McEachern Creek drainage divide area

Figure 6: Tetrau Creek-McEachern Creek drainage divide area from Toporama 1:150,000 scale map.

Figure 6 provides a big picture topographic map of the Tetrau Creek-McEachern Creek drainage divide area west of the figure 3 map area and includes overlap areas with figure 3. South-oriented drainage routes all flow eventually to the Frenchman River, which flows to the Milk River, which in turn flows to the Missouri River. Horse Creek is the south oriented drainage route next to the figure 6 east edge (south half). West of Horse Creek in map 72G2 is south-oriented Dunn Creek. McEachern Creek is a south-oriented stream in the eastern area of map 72G3 with Breed Creek being a major south-oriented stream originating in map 72G6 and flowing into map 72G3 near the figure 6 west edge. The Wood River is the east-southeast oriented drainage route in map 72G6 and turning to flow in a northeast direction in map 72G7 and north of the figure 6 map area flows to Old Wives Lake (see figure 1). Note how near Wideview (in figure 6 center) a north oriented Wood River tributary valley is linked by a shallow through valley with the south-oriented McEachern Creek valley. The figure 6 contour interval is 20 meters and the through valley is defined by one contour line on each side, although proceeding further from the valley in either direction reveals a second contour line. Proceeding further west note how a Breed Creek tributary appears to drain the White Lake and Soda Lake area north and east of 1000 meter high Wood Mountain upland surface remnants. Also note how multiple shallow through valleys link the east-southeast oriented Wood River valley with the south-oriented Breed Creek valley. The converging Breed Creek tributary valleys originated as converging flood flow channels in a south-oriented anastomosing channel complex, which was beheaded by headward erosion of the east-southeast oriented Wood River valley. The east-southeast oriented Wood River headwaters valley eroded headward to capture the south-oriented flood flow in sequence from east to west and to divert the flood waters to the northeast-oriented Wood River valley. While not included in this study region, the northeast-oriented Wood River valley eroded headward across southeast-oriented flood flow which was moving to what was at that time the actively eroding south- and southeast-oriented Big Muddy Creek valley (which had eroded headward from a northeast-oriented valley draining through a major breach in the ice sheet’s detached southwest margin). It is possible much of the area north of the Wood Mountain region was covered with ice and the northeast-oriented Wood River valley was being carved into a decaying ice mass as it captured the southeast-oriented flood flow.

Detailed map of Wood River-McEachern Creek drainage divide area

Figure 7: Detailed map of Wood River-McEachern Creek drainage divide area from Toporama 1:40,000 scale map.

Figure 7 provides a detailed topographic map of the Wood River-McEachern Creek drainage divide area near Wideview and seen in less detail in figure 6. North-oriented drainage at Wideview flows to the Wood River (located north of the figure 7 map area). Note how the north-northwest oriented headwaters of the northeast-oriented Wood River tributary has several south-oriented tributaries. South of the north-northwest oriented Wood River tributary headwaters in the figure 7 south center area are headwaters of south-oriented McEachern Creek, with water eventually reaching the Frenchman River. A well-defined north-south oriented through valley links the north-oriented Wood River tributary valley with the south-oriented McEachern Creek valley. The map 72G3 contour interval is 25 feet and the map 72G6 contour interval is 10 meters. The through valley floor elevation is between 3100 and 3125 feet. Elevations rise to more than 3275 feet on both sides of the through valley indicating the through valley is at least 150 feet deep. Other somewhat shallower through valleys can be found in the figure 7 east center area linking a southwest and northwest-oriented tributary to the northeast-oriented Wood River tributary with an unnamed south-oriented stream flowing to the figure 7 south edge (and eventually to the Frenchman River). Still another shallower through valley is located near the figure 7 east center edge. The multiple north-south oriented through valleys are further evidence the Wood Mountain upland region was eroded by an immense south-oriented anastomosing channel complex. South-oriented tributary valleys to the north-northwest oriented headwaters of the north-oriented Wood River tributary were eroded by south-oriented flood flow captured when flood flow on the north end of the south-oriented flood flow channel to the actively eroding McEachern Creek valley was beheaded and reversed by headward erosion of the deep Wood River valley (north of figure 7). Little Breed Creek is the labeled south-southwest oriented stream in the figure 7 west center edge area and Little Breed Creek tributaries can easily be recognized. Note how Little Breed Creek has several north-oriented tributaries. The north-oriented Little Breed Creek tributary valleys were eroded by reversals of flood flow on north ends of south-oriented flood flow channels beheaded by headward erosion of the deep Little Breed Creek valley. Note how several of the south-oriented Little Breed Creek tributary valleys are linked by shallow through valleys with north-oriented Wood River tributary valleys. These shallow through valleys provide additional evidence of the large anastomosing channel complex, which once crossed the Wood Mountain upland region.

Wood River-Breed Creek drainage divide area

Figure 8: Wood River-Breed Creek drainage divide area from Toporama 1:40,000 scale map.

Figure 8 provides a detailed map of the Wood River-Breed Creek drainage divide area near Soda Lake, which was seen in less detail in figure 6 and includes overlap areas with figure 7. North and east-oriented drainage routes in the figure 8 northeast corner drain to the Wood River, which is located north of the figure 8 map area. Headwaters of south-oriented Little Breed Creek are labeled and located in the figure 8 southeast quadrant. Breed Creek is not labeled, but flows in a south-southwest direction to the figure 8 west center edge area and then eventually to the Frenchman River. Note how the Soda Lake basin has no outlet stream even though on figure 6 it appeared to drain to Breed Creek. A through valley does link a southwest-oriented Breed Creek tributary valley with a northeast-oriented Soda Lake tributary valley. The map 72G6 contour interval is 10 meters and the through valley floor elevation appears to be between 920 and 930 meters with elevations exceeding 1000 meters located on either side. The Soda Lake basin is also linked by through valleys to the White Lake basin and to the east-oriented Wood River tributary valley in the figure 8 northeast corner. The floor of that Soda Lake-Wood River through valley also has an elevation of between 920 and 930 meters. In other words Soda Lake is located in a deeper basin located on the floor of a through valley linking the present day Wood River valley with the south-oriented Breed Creek valley. White Lake (located along the figure 8 north edge west of center) and an unnamed lake northwest of White Lake (not seen in figure 8, but seen in figure 9) are located in a closed basin, but are also linked by through valleys with north-oriented Wood River tributary valleys and by shallower through valleys with south-oriented Frenchman River tributary valleys. The lake basins were probably eroded by flood water scouring action as south-oriented flood flow routes were captured and diverted in an east direction to newly beheaded and reversed flood flow moving to the deeper east-southeast oriented Wood River headwaters valley which had eroded headward into the region.

Pinto Creek-Frenchman River drainage divide area

Figure 9: Pinto Creek-Frenchman River drainage divide area from Toporama 1:150,000 scale map.

Figure 9 provides a big picture topographic map of the Pinto Creek-Frenchman River drainage divide area west of the figure 6 map area and includes overlap areas with figure 6. Pinto Creek originates in the Glen McPherson area just west of the figure 9 north center edge area and flows in a north and then east direction to eventually reach the north-northeast oriented Wood River. Laville Creek is located east of the Pinto Creek headwaters and flows in a north and northeast direction to also join the Wood River. The Wood River originates just east of the Laville Creek headwaters (north of Pinto Butte) and flows in an east and east-southeast direction to the figure 9 east center edge. East of the figure 9 map area the Wood River turns to flow in a north-northeast direction to Old Wives Lake (see figure 1). North-oriented drainage routes in the figure 9 northeast corner are Laville Creek tributaries, with water eventually reaching the Wood River. The Frenchman River is the southeast-oriented stream in the figure 9 southwest corner region. South-southwest oriented Little Breed Creek and Breed Creek are labeled and flow across map 72G3 to the figure 9 south edge and then to the Frenchman River south of the figure 9 map area. Note how shallow through valleys link the north-oriented Pinto Creek and Laville Creek valleys with south-oriented Frenchman River tributary valleys. These through valleys provide evidence headward erosion of the deep southeast-oriented Frenchman River valley, probably into a topographic surface at least as high as the present day Wood River-Frenchman River drainage divide, first captured an immense south-oriented flood, which north of the present day Wood River-Frenchman River drainage divide had to be flowing on a surface at least as high as the present day drainage divide. Headward erosion of the east-southeast-oriented Wood River valley then beheaded south-oriented flood flow channels to actively eroding south-oriented Frenchman River tributary valleys in the figure 9 east half. Headward erosion of the Laville Creek valley, north of the newly eroded Wood River then beheaded and reversed south-oriented flood flow to the newly eroded Wood River valley and flood waters on north ends of the beheaded flood flow route reversed flow direction to erode north-oriented Laville Creek tributary and headwaters valleys. Next headward erosion of the Pinto Creek valley (north and then west of the Laville Creek valley captured the south-oriented flood flow and flood waters on north ends of the beheaded flood flow routes reversed flow direction to erode north-oriented Pinto Creek tributary and headwaters valleys.

Detailed map of Laville Creek-Frenchman River drainage divide area

Figure 10: Detailed map of Laville Creek-Frenchman River drainage divide area from Toporama 1:40,000 scale map.

Figure 10 concludes this essay with a detailed topographic map of the Laville Creek-Frenchman River drainage divide seen in less detail in figure 9 above (note the Pinto Butte location has migrated to the west in figure 10 from its figure 9 location). Laville Creek is the north-oriented stream flowing to the figure 10 north edge near Broncho. The Wood River headwaters flow to the figure 10 east center edge. Note how Wood River and Laville Creek headwaters originate in almost the same place before they diverge to flow along completely different routes and then end up eventually converging again north and east of the figure 10 map area. Pinto Creek headwaters flow to the figure 10 north edge west of Laville Creek (west of center). Breed Creek flows in a south direction near the figure 10 southeast corner. South-southwest oriented drainage routes west of Breed Creek are also Frenchman River tributaries as seen in figure 9. Again note how the north-oriented Wood River, Laville Creek, and Pinto Creek valleys are linked by shallow through valleys with south-oriented Frenchman River tributary valleys. The through valley near the figure 10 center area links the north-northeast oriented Laville Creek valley with a south-southwest oriented Frenchman Creek tributary valley. The through valley floor elevation is between 970 and 980 feet and elevations rise to more than 1010 meters on each side (the map contour interval is ten meters). To the northwest the through valley linking the unlabeled Pinto Creek headwaters valley with an unlabeled south-southwest oriented Frenchman River tributary valley also has a floor elevation of between 970 and 980 meters with elevations exceeding 1000 meters on either side. Near the figure 10 east center edge the through valley linking the Wood River headwaters valley with the south-oriented Breed Creek valley also has an elevation of between 970 and 980 meters. The similarity of these elevations suggests south-oriented flood waters were eroding all three of the through valleys at the same time, which means the Pinto Creek, Laville Creek, and Wood River valleys were all initiated as channels in what was a large complex of diverging and converging anastomosing flood flow channels supplying flood waters to actively eroding south-oriented Frenchman River tributary valleys. At that time flood waters were flowing on a topographic surface at least as high the present day through valley floors (970 to 980 meters) and probably as high as the higher drainage divide remnants (1010 meters plus). Headward erosion of deep valleys north of the figure 10 map area then beheaded the south-oriented flood flow channels in sequence from east to west (the north-northeast oriented Wood River valley was beheaded and reversed first) and flood waters on north ends of the beheaded flood flow routes reversed flow direction to erode the north-oriented valleys.

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.