South Fork Smith River-Missouri River drainage divide area landform origins, Meagher and Broadwater Counties, Montana, USA

Authors

Abstract:

Topographic map interpretation methods are used to interpret South Fork Smith River-Missouri River drainage divide area landform origins in the Big Belt Mountains area of Meagher and Broadwater Counties, Montana. West of the Big Belt Mountains the Missouri River flows in a north-northwest direction and then in a northeast direction north of the mountains. East of the Big Belt Mountains the South Fork Smith River flows in a north-northwest direction to joint the north-northwest Smith River, which then joins the northeast-oriented Missouri River. South of the South Fork Smith River headwaters is west-southwest oriented Sixteenmile Creek, which flows south of the Big Belt Mountains to join the Missouri River. Between the South Fork Smith River and the Missouri River are the high Big Belt Mountains which are drained in the west by southwest and west-oriented Missouri River tributaries and in the east by northeast, east, and north-oriented Smith River (and South Fork Smith River) tributaries. Through valleys (or mountain passes) link the west- and southwest-oriented Missouri River tributary valleys with the northeast, east, and north-oriented Smith River tributary valleys and provide evidence of multiple south-oriented diverging and converging flood flow channels that once crossed the region. At that time the Big Belt Mountains did not stand high above the surrounding regions as they do today and flood waters were free to flow across them. The south-oriented anastomosing flood flow channels was systematically dismembered by crustal warping that raised the Big Belt Mountains (and perhaps lowered adjacent basins and valleys) and by headward erosion of the deep northeast-oriented Missouri River valley north of the Big Belt Mountains, which 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 what are today north-oriented valleys. Flood waters are interpreted to have been derived from a rapidly melting thick North American ice sheet and were flowing from Canada in south and southeast directions across Montana.

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 Fork Smith River-Missouri River drainage divide area landform origins in Meagher and Broadwater Counties, Montana, USA. Map interpretation methods can be used to unravel many geomorphic events leading up to formation of present-day drainage routes and development of other landform features. While each detailed topographic map feature provides detailed evidence to be explained, the solution must be consistent with explanations for adjacent area map evidence as well as solutions to big picture map evidence puzzles. I invite readers to improve upon my solutions and/or to propose alternate solutions that better explain evidence and are also consistent with adjacent map area and big picture evidence. Readers may do so either by making comments here or by writing and publishing their own essays and by leaving comment here with a link their 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 South Fork Smith River-Missouri River drainage divide area landform evidence in Meagher and Broadwater Counties, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm (see essay listed at header). This essay is included in the Missouri River drainage basin landform origins research project essay collection.

South Fork Smith River-Missouri River drainage divide area location map

Figure 1: South Fork Smith River-Missouri River drainage divide area location map (select and click on maps to enlarge). National Geographic Society map digitally presented using National Geographic Society TOPO software.
  • Figure 1 illustrates a region in central Montana and provides a location map for the South Fork Smith River-Missouri River drainage divide area in Meagher and Broadwater Counties. The east-west continental divide (not marked or labeled in figure 1) extends in a south-southeast direction from the figure 1 north edge (near northwest corner) along or near the Lewis and Clark Range crest and then between Helena and Butte before turning in a west direction between Anaconda and the Big Hole River to reach the figure 1 west edge (south half). Figure 1 regions east of the continental divide drain to the Missouri River with water eventually reaching the Gulf of Mexico. The Missouri River is formed at Three Forks (in figure 1 south center area) at the confluence of the north-oriented Gallatin River, north-oriented Madison River (not labeled in figure 1), and northeast and east-oriented Jefferson River. From Three Forks the Missouri River flows in a north and north-northwest direction along the southwest side of the Big Belt Mountains and then near Wolf Creek turns to flow in a northeast direction to Great Falls Fort Benton, and Loma (on figure 1 north edge). The Smith River is formed just west of White Sulphur Springs (east of Big Belt Mountains) at the confluence of its north-northwest oriented South Fork and southwest-oriented North Fork and then flows in a north-northwest direction along the northeast side of the Big Belt Mountains to join the northeast-oriented Missouri River near Ulm (near Great Falls). The South Fork Smith River begins as a southeast-oriented stream south of Elk Peak and then makes a U-turn (north of Ringling) to flow in a north-northwest direction between Mt Edith in the Big Belt Mountains and Elk Peak in the Castle Mountains (not labeled in figure 1). South of Ringling is a south-southeast oriented stream flowing to the south-southeast oriented Shields River, which flows to the north-northeast and east oriented Yellowstone River near Livingston. East of the figure 1 map area the Yellowstone River turns to flow in a northeast direction and eventually joins the Missouri River in northwest North Dakota. The unlabeled west-southwest oriented Missouri River tributary flowing through Ringling is Sixteenmile Creek.The unlabeled north-oriented Smith River tributary directly north of Mt Edith is Camas Creek. The South Fork Smith River-Missouri River drainage divide area investigated in this essay is located north of Sixteenmile Creek, south of Camas Creek, west of the South Fork Smith River (and Smith River) and east of the Missouri River and includes high Big Belt Mountain regions. Essays describing other Smith River drainage divide areas can be found by selecting Smith River from this essay’s sidebar category list.
  • Drainage routes and mountain ranges in the figure 1 map area (and in a much larger region) evolved as deep valleys eroded headward into the region from both the east and west to capture immense south and southeast-oriented floods. Flood waters were derived from a rapidly melting thick North American ice sheet located in a deep “hole.” The deep “hole” evolved as the result of deep glacial erosion (under the ice sheet) and of crustal warping that raised mountain ranges along ice sheet margin and elsewhere in the continent, including mountain ranges in the figure 1 map area. The figure 1 mountain ranges were uplifted as massive south and southeast-oriented melt water floods flowed across them. The Missouri River drainage basin in Montana and northern Wyoming is the eroded remains of the deep “hole’s” southwest wall. The deep “hole’s” western rim developed as the western Alberta and eastern British Columbia Rocky Mountain ranges emerged while massive south and southeast-oriented ice-marginal floods flowed across them and then into and across Montana along routes corresponding with the present day east-west continental divide. The east-west continental divide south of Montana and northern Wyoming was carved from south to north by headward erosion of deep valleys from the Gulf of Mexico in the east and from the Pacific Ocean in the west to capture massive melt water flood flow moving along what were then rising Rocky Mountain ranges (with uplift in the south preceding uplift in the north). Eventually a combination of crustal warping and of ice sheet melting created a situation where elevations south and west of the ice sheet southwest margin were higher than at least some elevations on the decaying ice sheet surface (especially near the ice sheet’s south margin).
  • Of particular importance to this essay were giant south oriented ice-walled canyons carved into the ice sheet surface by huge south oriented supra-glacial melt water rivers, especially a giant southeast and south oriented  ice-walled canyon in present day Saskatchewan, North Dakota, and South Dakota. This giant ice-walled canyon subsequently became a bedrock-floored canyon and detached the ice sheet’s southwest margin. Today the northeast and east facing Missouri Escarpment is what remains of that giant ice-walled canyon’s southwest and west wall. Deep east and northeast oriented valleys eroded headward from that giant ice-walled canyon into Montana and northern Wyoming to capture the immense south and southeast-oriented melt water floods. These valleys eroded headward in sequence with headward erosion of each deep valley beheading south- and southeast-oriented flood routes to the newly eroded valley immediately to the south or southeast. The deep east and northeast-oriented Yellowstone River valley captured the south- and southeast-oriented flood first, with flood waters on north ends of beheaded flood flow channels reversing flow direction to erode north-oriented tributary valleys. Headward erosion of the deep Missouri River valley then beheaded flood flow routes to the newly eroded Yellowstone River valley and again flood waters on north ends of beheaded flood flow channels reversed flow direction to erode north-oriented tributary valleys. The north-northwest oriented Smith River valley in figure 1 was eroded by such a flood flow reversal. The flood flow reversal may have been aided by crustal warping that raised mountain ranges in the figure 1 map area. Northeast-oriented Missouri River valley headward erosion then continued west of where the newly eroded Yellowstone River drainage basin was located and beheaded a major south-oriented oriented flood flow channel on the present day north-northwest oriented Missouri River alignment. The south-oriented flood flow was probably flowing to at least three major diverging south-oriented flood flow channels at Three Forks, with each diverging flood flow channel having been eroded headward from what was the newly eroded Snake River valley west of Yellowstone National Park (south of figure 1). Flood waters on the north end of the beheaded flood flow channel reversed flow direction to erode the north-northwest oriented Missouri River valley segment and the north-oriented Gallatin, Madison, and Jefferson River valleys. Again crustal warping that was raising mountain ranges in the region at the time probably aided in this massive flood flow reversal.

Detailed location map for South Fork Smith River-Missouri River drainage divide area

Figure 2: Detailed location map for South Fork Smith River-Missouri River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 2 provides a detailed location map for the South Fork Smith River-Missouri River drainage divide area in Meagher and Broadwater Counties, Montana. Meagher and Broadwater Counties are labeled and the boundary between them is the defined by the drainage divide along the Big Belt Mountain crest, which for most its distance is the Smith River-Missouri River drainage divide. Park County is located south of Meagher County in the figure 2 southeast corner and Gallatin County is the county west of Park County and seen in the figure 2 south center edge area. The Missouri River flows in a north-northwest direction from the figure 2 south edge (at the Broadwater-Gallatin County border) to the figure 2 northwest corner. Canyon Ferry Lake is a large lake flooding the Missouri River valley with Canyon Ferry Dam located near the figure 2 northwest corner. Named southwest and west-oriented Missouri River tributaries from north to south include Magpie Creek, Avalanche Creek, White Creek, Confederate Gulch, Duck Creek, Gurnett Creek, Ray Creek, Deep Creek, Dry Creek, Sixmile Creek, and Sixteenmile Creek. The Smith River is formed a short distance west and south of White Sulphur Springs (in figure 2 northeast quadrant) at the confluence of its southwest oriented North Fork and its north-northwest oriented South Fork and then flows in a north-northwest direction to the figure 2 north center edge. The South Fork Smith River originates south of the Castle Mountains as a southeast-oriented stream and makes a U-turn to flow in a north-northwest direction to join the southwest-oriented North Fork and to form the northwest-oriented Smith River. Named Smith River tributaries from the west include east and north oriented Camas Creek, north- and northeast-oriented Thompson Creek, north- and northeast-oriented Birch Creek-the last two of which originate south of the North Fork-South Fork Smith River confluence area. No South Fork Smith River tributaries from the west are shown. The southwest- and west-oriented stream flowing through Ringling is Sixteenmile Creek, which originates south and east of the South Fork Smith River headwaters and which flows to the Missouri River near the figure 2 south edge. South of Ringling are south-oriented headwaters of Potter Creek, which south of the figure 2 map area flows to the south-southeast oriented Shields River, which in turn flows to the east-oriented Yellowstone River. Note how west of the south-oriented Potter Creek headwaters there are two north-oriented Sixteenmile Creek tributaries. The opposing Smith River and Shields River drainage routes developed because the north-northwest to south-southeast oriented valley now drained by the north-northwest oriented Smith River and the south-southeast oriented Shields River was initiated as a south-southeast oriented flood flow channel. Headward erosion of the deep west-oriented Sixteenmile Creek valley probably from a south-oriented flood flow channel on the present day Missouri River valley alignment captured the south-oriented flood flow and headward erosion of the deep northeast-oriented Missouri River valley north of the figure 2 beheaded and reversed the south-oriented flood flow to erode the north-northwest oriented Smith River and South Fork Smith River valleys. Subsequently northeast-oriented Missouri River valley headward erosion beheaded and reversed the south-oriented flood flow channel on the present day Missouri River valley alignment.

Little Camas Creek-Gurnett Creek drainage divide area

Figure 3: Little Camas Creek-Gurnett Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 3 illustrates the Little Camas Creek-Gurnett Creek drainage divide area near Duck Creek Pass. The Smith River-Missouri River drainage divide serves as the Meagher County-Broadwater border and is located along the crest of the high Big Belt Mountains which extends from the figure 3 north edge (west half) to the figure 3 south edge (near southeast corner). Drainage routes east of the drainage divide flow to the north-northwest oriented Smith River while drainage routes west of the drainage divide flow to the north-northwest oriented Missouri River. Duck Creek Pass is located near the figure 3 center. North of Duck Creek Pass are headwaters of northeast-oriented Little Camas Creek, which joins east-oriented Big Camas Creek to form north-oriented Camas Creek which flows to the figure 3 north edge (east of center) and then to join the Smith River north of figure 3. Directly southwest of the Little Camas Creek headwaters are headwaters of south-west-oriented Gurnett Creek which turns to flow in more of a west direction near the figure 3 west edge (south half) and which joins the Missouri River west of figure 3. North of Gurnett Creek is south, southwest, and west oriented Duck Creek. The east- and northeast-oriented stream originating at Duck Creek Pass is Gipsy Creek which joins north-northeast and northeast oriented Big Birch Creek in the figure 3 northeast quadrant. Big Birch Creek originates in what look like some north-oriented cirques located between Mount Baldy and Mount Edith near the figure 3 south edge. North and east of figure 3 Big Birch Creek also flows to the Smith River. The figure 3 map contour interval is 50 meters and the Duck Creek Pass elevation is shown as 2291 meters. Mount Baldy to the south has an elevation of 2887 meters while Boulder Mountain to the north has an elevation greater than 2600 meters (Boulder Baldy just north of figure 3 has an elevation of 2726 meters). The Big Belt Mountain crest between Boulder Mountain and Mount Baldy is lower in elevation than those two high points and at Duck Creek Pass is at least 300 meters lower in elevation. While today the Smith River-Missouri River drainage divide in this area is a high mountain ridge this deep indentation in that high ridge is evidence of a former south-oriented flood flow channel. Flood waters were probably flowing in a southwest direction to what was at that time a deep south-oriented flood flow channel on the present day north-oriented Missouri River alignment. Headward erosion of a deep south-southeast oriented flood flow channel on the present day north-oriented Smith River alignment beheaded and reversed the southwest-oriented flood flow. A combination of Big Belt Mountain uplift and of northeast-oriented Missouri River valley headward erosion north of the figure 3 map area reversed flood flow on the north end of the Smith River flood flow channel and subsequently in the Missouri River valley to the west of figure 3.

Detailed map of Little Camas Creek-Gurnett Creek drainage divide area

Figure 4: Detailed map of Little Camas Creek-Gurnett Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 4 provides a more detailed topographic map of the Little Camas Creek-Gurnett Creek drainage divide area seen in less detail in figure 3 above. The Smith River-Missouri River drainage divide is the county line and extends from near the figure 4 northwest corner to the figure 4 south center edge. Duck Creek Pass is located in section 32 and has an elevation of between 7480 and 7520 feet (the figure 4 map contour interval is 40 feet). A lower unnamed pass is found in section 30 linking the northeast-oriented Little Camas Creek valley with a southwest-oriented Duck Creek tributary valley. The lower pass elevation at the drainage divide is between 7320 and 7360 feet. Note in section 24 to the northwest a spot elevation of 8442 feet and elevations of more than 8500 feet on the figure 4 south center edge (Boulder Mountain and Boulder Baldy north of figure 4 reach 8810 feet and 8942 feet respectively while Mount Baldy south of figure 4 reaches 9467 feet). Depending on which elevations are chosen the unnamed pass (or through valley) is at least 1000 feet deep and may be even deeper. While today it is difficult to imagine a large southwest-oriented valley crossing the figure 4 map area the low area (between the high points to the north and south in figure 4) is a water eroded feature and is evidence of former southwest-oriented valley. As will be seen in subsequent topographic maps illustrated in this essay this southwest-oriented valley is just one of several that once crossed what is now the high Big Belt Mountains crest. These multiple southwest-oriented valleys are best explained in the context of diverging and converging flood flow channels such as might be found in a large south-oriented anastomosing channel complex. At that time the flood waters were eroding deep flood flow channels into an erosion surface equivalent in elevation to the highest elevations along the Big Belt Mountains crest, which means the Big Belt Mountains did not stand high above surrounding regions as they do today. Flood waters were probably flowing to what was then a south-oriented major flood flow channel on the present day north-oriented Missouri River alignment and then south to what was probably then the deep west-oriented Snake River valley, which probably was eroding headward into the region west and south of present day Yellowstone National Park. Delayed crustal warping caused by the rapidly melting thick ice sheet’s tremendous weight and perhaps by crustal unloading (related to the removal of great thicknesses of bedrock from the rising Big Belt Mountain mass) was probably beginning to raise the Big Belt Mountains as flood water flowed across then. Headward erosion of the deep northeast-oriented Missouri River valley north of the figure 4 map area beheaded the south-oriented flood flow and combined with the crustal warping reversed flood waters in the Smith River drainage basin and subsequently in the Missouri River valley to the west.

Big Birch Creek-Ray Creek drainage divide area

Figure 5: Big Birch Creek-Ray Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 5 illustrates the Big Birch Creek-Ray Creek drainage divide area south of the figure 3 map area and includes overlap areas with figure 3. The county line, which is defined by the Smith River-Missouri River drainage divide extends in a south direction from near the figure 5 north center edge to Mount Baldy and then in an east direction to Mount Edith. From Mount Edith the county line extends in an east-northeast and then south direction to the figure 5 south edge (east half). Duck Creek Pass is located south of the figure 5 north center edge and Gurnett Creek is the southwest oriented stream originating just to the west. Duck Creek is the south, southwest, and west-oriented stream north of Gurnett Creek. Big Birch Creek originates in the north-facing basin between Mount Baldy and Mount Edith and flows in a north and north-northeast direction to the figure 5 north edge (east half) and north and east of figure 5 joins the north-northwest oriented Smith River. Little Birch Creek is the northeast-oriented stream east of Big Birch Creek and originates near the Needles and flows to the figure 5 north edge (near northeast corner). Butte Creek is the north-oriented Little Birch Creek tributary east of Little Birch Creek and is linked by a north-south oriented through valley (or mountain pass) with the south-oriented Russell Fork Deep Creek, which flows to the figure 5 south edge just west of the county line (and the drainage divide). The figure 5 map contour interval is 50 meters and the through valley floor elevation is between 2250 and 2300 meters. Windy Ridge to the south and east rises to 2356 meters while Mount Edith to the west rises to 2860 meters. Using the Windy Ridge elevation the through valley is at least 100 meters deep and provides evidence of a south-oriented flood flow channel to what was once the actively eroding Deep Creek valley (which today drains in a west direction to the north-oriented Missouri River as a barbed tributary). The Butte Creek-Russell Fork Deep Creek through valley is easy to visualize, but other more subtle through valleys (or mountain passes) are located between Mount Baldy and Mount Edith to the west. Mount Baldy has an elevation of 2887 meters while Mount Edith has an elevation of 2860 meters (remarkably similar elevations). The high ridge between the two peaks dips to a low point of between 2650 and 2700 feet near Mount Baldy suggesting a south-oriented flood flow once existed between what are today the two highest points on figure 5. South of the that high level through valley are southwest and west-oriented headwaters and tributaries of west-oriented Ray Creek, which west of figure 5 flows to the north-oriented Missouri River valley. South-oriented streams east of the Ray Creek headwaters are Deep Creek tributaries. The 160 meter deep through valley (or mountain pass) plus the valley orientations to the north and south suggest at one time a south-oriented flood flow channel once flowed between Mount Baldy and Mount Edith. This evidence provides important clues as to the amount of erosion that flood waters accomplished and/or the amount of uplift that was occurring while flood waters flowed across the region and that has occurred since that time. What appear to be cirques in the Big Birch Creek headwaters region were formed after the region had been uplifted and flood waters were long gone from the region.

Detailed map of Big Birch Creek-Ray Creek drainage divide area

Figure 6: Detailed map of Big Birch Creek-Ray Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 6 provides a detailed topographic map of the Big Birch Creek-Ray Creek drainage divide area seen in less detail in figure 5 above. Big Birch Creek is the north oriented stream flowing to the figure 6 north center edge and has multiple tributaries originating in what appear to be north-, northeast, and east facing cirques located on the east and north side of the Meagher County-Broadwater County boundary, which is defined by the Smith River-Missouri River drainage divide. Big Birch Creek flows to the north-northwest oriented Smith River (north and east of figure 6). Ray Creek originates in section 21 and flows in a southwest and south direction to the figure 6 south edge (west half). South-oriented streams flowing to the figure 6 south edge west of Ray Creek are tributaries to North Fork Deep Creek (south of figure 6 map area), which flows to west-oriented Deep Creek. Ray Creek and Deep Creek are Missouri River tributaries. The Big Birch Creek-Ray Creek drainage divide area appears to be about the last place to look for evidence of a south-oriented melt water flood flow channel, yet a close look at the drainage divide reveals just such evidence. Mount Baldy (found on the border between the section 17 southeast corner and the section 20 northeast corner) reaches an elevation of 9467 feet (the figure 6 map contour interval is 40 feet). Mount Edith in the east half of section 23 reaches an elevation of between 9480 and 9520 feet. Between Mount Baldy and Mount Edith the drainage divide is lower-often several hundred feet lower. The lowest point is in section 21 and identifies a through valley (or mountain pass) linking the southwest-oriented Ray Creek headwaters with a northeast-oriented Big Birch Creek tributary valley. This lowest point has an elevation at the drainage divide of between 8760 and 8800 feet, which is at least 667 feet lower than the adjacent mountain peaks. This through valley (or mountain pass) is a water eroded feature and was eroded at a time when the region north and east of the present day drainage divide was at least as high as the drainage divide today (although crustal warping may have raised the entire region since). Water that eroded the through valley was moving in a south and southwest direction to what was probably at that time a south-oriented flood flow channel on the present day north-oriented Missouri River alignment. Flood flow was reversed by headward erosion of the deep northeast-oriented Missouri River valley north of the figure 6 map area, which systematically reversed flood flow in the present Smith River drainage basin from east to west. The reversed flood flow aided by yet to be beheaded and reversed flood flow from south and west of the actively eroding Missouri River valley eroded deep north-oriented Smith River tributary valleys, including the Big Birch Creek valley seen in figure 6.
  • The question may validly be asked “how and when did alpine glaciers form in the Big Birch Creek headwaters region so as to carve the cirques seen today?” At the time immense south-oriented melt water floods from the rapidly melting thick ice sheet flowed across figure 6 and began to carve the deep valleys regional elevations and climates were not conducive to alpine glacier formation. In fact, the climate was causing the thick ice sheet to melt faster and faster. What was happening was immense south-oriented melt water floods were flowing to the Gulf of Mexico and forcing warm Gulf of Mexico water into the Atlantic Ocean and then northward to the North Atlantic Ocean. Movement of warm waters northward warmed the North American continent and caused the thick ice sheet to melt faster, which in turn led to larger melt water floods and more climate warming. This situation changed when ice sheet melting reached the point that the immense south-oriented melt water floods flowing in giant ice-walled and bedrock-floored canyons were captured by north-oriented ice-walled and bedrock-floored canyons, which had been carved headward from the North Atlantic and Arctic Oceans. The north-oriented ice-walled and bedrock-floored canyons offered much shorter routes to sea level and eventually captured most of the decaying ice sheet’s melt water floods, including the ice-marginal flood waters moving across Montana and northern Wyoming. The shift of the massive melt water floods from the Gulf of Mexico to the North Atlantic and Arctic Oceans completely changed the North American climate. Instead of warm Gulf of Mexico water moving north cold North Atlantic and Arctic Ocean water pushed south to cool the continent. The thick ice sheet rapid melt down stopped and the north-oriented melt water floods froze on the floors of the giant ice-walled and bedrock-floored canyons. The result was a thin sheet of frozen melt water surrounding thick ice sheet remnants. By that time crustal warping had raised mountain ranges, which had been deeply eroded by flood water erosion (such as the Big Belt Mountains seen in figure 6), and conditions were ideal for alpine glacier formation. In time the North American climate gradually improved and the thin ice sheet and some of the alpine glaciers gradually melted, although without massive floods and deep flood water erosion the rapidly melting thick ice sheet had produced.

North Fork Cooks Creek-Deep Creek drainage divide area

Figure 7: North Fork Cooks Creek-Deep Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 7 illustrates the North Fork Cooks Creek-Deep Creek drainage divide area south and east of figure 5  and includes overlap areas with figure 5. Mount Edith is located near the figure 7 west edge (north of center). The county line which is defined by the Smith River-Missouri River drainage divide is marked with a dashed line extending from Mount Edith in an east-northeast and then south direction with an east and west jog around the Deep Creek headwaters to eventually reach the figure 7 south edge (west half). Windy Ridge is a labeled north-south oriented ridge located in the Broadwater County (west half of figure 7). The south-oriented stream located on the west side of Windy Ridge is the Russell Fork Deep Creek while the south-oriented stream on the east side of Windy Ridge is Deep Creek, which west of the Grass Mountain Ski Area (near south edge in figure 7 southwest quadrant) turns to flow in a southwest direction to the figure 7 south edge (near southwest corner). South and west of figure 7 Deep Creek flows to the north-northwest oriented Missouri River. The Castle Fork Deep Creek is the west-oriented Deep Creek tributary joining Deep Creek near the Grass Mountain Ski Area. Battle Creek is the east-oriented stream originating just east of the west-oriented Castle Fork Deep Creek headwaters. South of the figure 7 map area Battle Creek turns to flow in a southwest and south direction to join west-oriented Sixteenmile Creek, which is a Missouri River tributary. Note how the west-oriented Castle Fork Deep Creek and the east-oriented Battle Creek headwaters are linked by a deep through valley. The through valley floor elevation is between 1750 and 1800 meters (the figure 7 map contour interval is 50 meters). Elevations on the ridge to the north rise to 2135 meters and elevations on the ridge to the south (not seen in figure 7) rise to 2343 meters making the through valley at least 335 meters deep. The through valley was eroded by diverging flood flow channels on the south-oriented Deep Creek alignment, with one flood flow channel moving water to a south-oriented flood flow channel on the Missouri River alignment while the other flood flow channel moved water to a south-oriented flood flow channel on the South Fork Smith-Shields River alignment. The South Fork Smith River flows in a north-northwest direction from the figure 7 east edge (south half) to the figure 7 north edge (east half). Springdale Colony is a community in the figure 7 north center region. Cooks Creek flows in a north-northeast direction just west of Springdale Colony and is a South Fork Smith River tributary. The North Fork Cooks Creek originates near the north end of Windy Ridge and flows in an east-northeast direction to join the north-northeast oriented South Fork Cooks Creek south and west of Springdale Colony. Note how the North Fork Cooks Creek valley is linked by a through valley with the south-oriented Deep Creek headwaters valley. The through valley floor elevation is between 1950 and 2000 meters while elevations to the southeast rise to 2135 meters and to the  northwest rise to more than 2350 meters. This 235 meter deep through valley was eroded by south-oriented flood flow prior to reversal of flood flow in the Smith River valley. Flood flow in the Smith River valley was reversed by headward erosion of the much deeper northeast-oriented Missouri River valley (north of figure 7) and probably by crustal warping that raised the Smith River headwaters area (i.e. the figure 7 map region).

Detailed map of North Fork Cooks Creek-Deep Creek drainage divide area

Figure 8: Detailed map of North Fork Cooks Creek-Deep Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 8 provides a detailed topographic map of the North Fork Cooks Creek-Deep Creek drainage divide area seen in less detail in figure 7 above. The Meagher County-Broadwater County border is marked with a dashed line and extends in a southeast and south direction from the figure 8 northwest corner to the figure 8 south edge (east of center). The county line is defined by the Smith River-Missouri River drainage divide. North Fork Cooks Creek flows in an east direction near the north edge of the figure 8 northwest quadrant. Headwaters of the north-northeast oriented South Fork Cooks Creek originate in sections 26, 35 (northeast half), and 30 (north half) and the South Fork Cooks Creek flows to the figure 8 north edge (near northeast corner) and joins the North Fork north and east of figure 8 to form north-northeast oriented Cooks Creek, which then flows to the north-northwest oriented South Fork Smith River. Deep Creek originates in the section 21 southwest quadrant and flows into section 28 and then in a south direction to the figure 8 south edge. South of figure 8 Deep Creek turns to flow in a southwest and west direction to join the north-northwest oriented Missouri River. Note just south of the corner between sections 21, 22, 27, and 28 a through valley linking a northeast-oriented North Fork Cooks Creek tributary valley with the south-oriented Deep Creek valley. The figure 8 map contour interval is 40 feet and the through valley floor elevation is shown as 6393 feet. The hilltop in the south half of section 27 rises to 7205 feet while elevations greater than 7800 feet can be seen on the drainage divide near the figure 8 northwest corner. This through valley is at least 800 feet and is a water eroded feature. The through valley was initially a south-oriented flood flow channel diverging from a much broader south-southeast oriented flood flow channel on the Smith River-South-Fork Smith River alignment. This diverging flood flow channel was probably moving flood waters to a south-oriented flood flow channel on the present day north-oriented Missouri River valley alignment. This diverging flood flow channel provides evidence of a massive south-oriented anastomosing flood flow channel complex that once crossed central Montana. The anastomosing channel complex was dismembered by headward erosion of the much deeper northeast-oriented Missouri River valley north of the figure 8 map area and by crustal warping that raised the figure 8 map region. The south-oriented flood flow channels were beheaded and reversed in sequence from east to west to erode the north-northwest-oriented Smith River valley and tributary valleys and subsequently to erode the north-northwest oriented Missouri River valley and tributary valleys.

South Fork Smith River-Sixteenmile Creek drainage divide area

Figure 9: South Fork Smith River-Sixteenmile Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 9 illustrates the South Fork Smith River-Sixteenmile Creek drainage divide area south and east of figure 7 and includes overlap areas with figure 7. The forested upland straddling the figure 9 north edge near the figure 9 northeast corner is the south margin of the Castle Mountains. Moss Agate is a small town located in the figure 9 northeast quadrant. The South Fork Smith River originates as a southeast-oriented stream on the Castle Mountain south margin and then makes a U-turn to flow in a northwest direction to Moss Agate and then to the figure 9 north center edge and north of figure 9 joins the North Fork Smith River to form the north-northwest oriented Smith River. Ringling is the small town located in the figure 9 southeast quadrant. Sixteenmile Creek flows in northwest and then west-southwest direction from the figure 9 southeast corner to Ringling and then to the figure 9 south center edge. South and west of figure 9 Sixteenmile Creek joins the north-northeast and northeast oriented Missouri River. Note how the South Fork Smith River valley and the Sixteenmile Creek valley are linked by multiple north-south oriented through valleys. The figure 9 map contour interval is 50 meters and several of the through valleys show no contour lines between the north-oriented South Fork Smith River valley and the west-oriented Sixteenmile Creek valley. Battle Creek flows in an east direction from the figure 9 west edge (just north of center-it is the stream with a small reservoir located on it) and then makes a gradual turn to flow in a southwest and south direction to the figure 9 southwest corner and south and west of figure 9 joins west-oriented Sixteenmile Creek. Note how the  and south oriented Battle Creek valley is linked by a through valley with the north oriented Mayns Creek valley which drains to the figure 9 north edge (west of center) and which joins the South Fork Smith River north of the figure 9 map area. The north-south oriented through valleys seen in figure 9 are water eroded features and were initially eroded as south-oriented flood flow channels continuing southward to the south-oriented Shields River valley (south of figure 9 and the Sixteenmile Creek valley).  The Shields River drains to the east-oriented Yellowstone River. Crustal warping occurred as flood waters flowed across the figure 9 map area and raised elevations in the figure 9 map area, which combined with headward erosion of the deep northeast-oriented Missouri River valley north of the figure 9 map area caused a reversal of flood flow north of the figure 9 that eroded the north-northwest oriented Smith River-South Fork Smith River valley. Shortly before Smith River reversal headward erosion of the Sixteenmile Creek valley from what was probably still a south-oriented flood flow channel on the present day north-northwest oriented Missouri River alignment had captured south-oriented flood flow in the large Smith River-Shields River flood flow channel complex seen in figure 9. Shortly after this capture flood flow in the Smith River drainage basin was beheaded and reversed to create the present north-oriented Smith River and the South Fork Smith River-Sixteenmile Creek drainage divide.

Detailed map of Mayns Creek-Battle Creek drainage divide area

Figure 10: Detailed map of Mayns Creek-Battle Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 
  • Figure 10 provides a detailed topographic map of the Mayns Creek-Battle Creek drainage divide area seen in less detail in figure 9 above. Black Butte Mountain is the high point seen in section 19 and reaches an elevation of 6436 feet (the figure 10 map contour interval is 20 feet). Mayns Creek (unlabeled in figure 10-but parallels Sixteenmile Road) originates in section 14 and flows in a north and north-northeast direction to the figure 10 north center edge in section 11. North of the figure 10 map area Mayns Creek flows to the north-northwest oriented South Fork Smith River. Battle Creek flows in an east-southeast direction in the figure 10 southwest quadrant. South of figure 10 Battle Creek turns to flow in a southwest and south direction to join west-oriented Sixteenmile Creek, which then flows to the north-northwest oriented Missouri River. Sixteenmile Creek Road which extends from section 22 across sections 14 and 11 to the figure 10 north center edge follows a through valley linking the north-northeast oriented Mayns Creek valley with the Battle Creek valley (which is oriented in a south and southwest direction south of the figure 10 map area). The Battle Creek-Mayns Creek drainage divide is located in section 22 near the J Stewart Ranch and has an elevation of between 5540 and 5560 feet. The high point in section 16 to the northwest is 5887 feet (and there are much higher elevations west of figure 10) while as already noted Black Butte Mountain rises to 6436 feet. In other words the through valley is at least 300 feet deep and probably is much deeper. The through valley is definitely a water eroded feature and was probably initially eroded by south-oriented flood flow although late in its history it may have been eroded as a north-northeast oriented diverging flood flow channel from an east-southeast and south oriented Battle Creek flood flow channel. This change in flood flow direction may have occurred because headward erosion of the deep northeast-oriented Missouri River valley (north of figure 10) beheaded south-oriented flood flow channels in sequence from east to west. In other words the Smith River-Shields River flood flow channel was beheaded and reversed before flood flow channels further to the west were beheaded and reversed. The east-southeast oriented Battle Creek flood flow channel probably was still obtaining south-oriented flood flow from west of the Smith River-Shields River flood flow channel alignment and was moving that flood flow eastward into the Smith River-Shields River flood flow channel. Once in the Smith River-Shields River flood flow channel valley the Battle Creek flood flow channel split with one of the diverging flood flow channels moving water in a north-northeast direction to the newly reversed South Fork Smith River valley and the other flood flow channel moving flood water in a south and west direction to what was then the newly eroded west-oriented Sixteennmile Creek valley. Headward erosion of the north-northeast oriented flood flow channel valley (Mayns Creek valley) almost captured the east-oriented Battle Creek flood flow channel, but flood flow to the region ended before the capture could occur.
  • Note: Flood flow movements in the South Fork Smith River-Missouri River drainage divide area were much more complex than described in this short essay. This essay has only pointed to a few of the most obvious topographic map features providing evidence. Interpretations given in this essay should not be considered final. In some cases the evidence is limited and alternate flood flow directions could explain topographic map evidence seen. The important points made by this essay are the Big Belt Mountains region was eroded by massive south-oriented floods at a time when the mountains were being uplifted and the north-northwest oriented Smith River and Missouri River valleys were initiated as south-oriented flood flow channels.

Additional information and sources of maps studied

This essay has provided only a sample of the detailed topographic map evidence supporting the flood erosion interpretation. Many additional illustrations could be provided. Readers are encouraged to look at mosaics of detailed topographic maps to see the abundance of available data. Maps used in this study were created and published by the United States Geologic Survey and can be obtained directly from the United States Geological Survey and/or from dealers offering United States Geological Survey maps. Hard copy maps can also be observed at United States Geological Survey map depositories, which are located throughout the United States and elsewhere. Illustrations used here were created using National Geographic Society TOPO software and digital map data. TOPO software and map data can be obtained from the National Geographic Society and/or dealers offering National Geographic Society digital map data.

1 Comment

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  1. Eric Clausen

    I welcome comments, especially comments offering suggestions about how to better explain origins of the erosional landforms discussed in this essay.

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