Madison River-Gallatin River drainage divide area landform origins in Madison Range (north), Madison and Gallatin Counties, Montana, USA

Authors


Abstract:

This essay uses topographic map evidence to interpret landform origins between the Madison River and Gallatin River in the northern Madison Range and south of Three Forks in Madison and Gallatin Counties, Montana. The Madison River flows in north direction from Ennis Lake through Bear Trap Canyon on the west side of the Madison Range while the Gallatin River flows in a north direction on the east side of the Madison Range. North of the Madison Range the Gallatin River turns to flow in a northwest direction to join the Madison River and northeast oriented Jefferson River at Three Forks and to form the north oriented Missouri River. Water gaps eroded through mountain ridges, barbed tributaries, and through valleys linking Madison River tributary valleys with Gallatin River tributary valleys provide evidence of south and southeast oriented flood flow channels that once crossed all drainage divides, including drainage divides in the northern Madison Range. The southeast oriented flood flow channels were captured by headward erosion of deeper south oriented flood flow channels on alignments of the present day north oriented Madison and Gallatin River alignments. Floodwaters were derived from the western margin of a thick North American ice sheet, which was located in a deep “hole”, and were flowing in south and southeast directions from western Canada across Montana. At that time Montana and adjacent state mountain ranges had not yet emerged and floodwaters freely flowed across the region. Mountain ranges and high plateau areas emerged as ice sheet related tectonic activity created the deep “hole” in which the ice sheet was located and as deep south oriented valleys eroded headward into the rising mountain masses. Headward erosion of a much deeper northeast oriented Missouri River valley segment north of the study region from space in the deep “hole” being opened up by ice sheet melting beheaded the south oriented flood flow channel supplying floodwaters to the south oriented flood flow channels on the Madison and Gallatin River alignments. Floodwaters on the north ends of the beheaded flood flow channel reversed flow direction to create the north oriented Missouri, Madison, and Gallatin River drainage routes. This massive flood flow reversal was greatly aided by ice sheet caused crustal warping that raised the Madison Range and other area mountain ranges and upland areas, including Yellowstone Plateau area where the north oriented Madison and Gallatin Rivers originate.

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 are listed on the sidebar category list under their appropriate Missouri River tributary drainage basin, Missouri River segment drainage basin (by state), and/or state in which the Missouri River drainage basin is located.

Introduction

The purpose of this essay is to use topographic map interpretation methods to explore the Madison River-Gallatin River drainage divide area landform origins in the northern Madison Range located in Madison and Gallatin Counties, Montana and 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 Missouri River drainage basin landform origins research project essays 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 Madison River-Gallatin River drainage divide area landform evidence in the northern Madison Range region of Madison and Gallatin Counties, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Madison River-Gallatin River drainage divide area location map

Figure 1: Madison River-Gallatin 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 provides a location map for the Madison River-Gallatin River drainage divide in the northern Madison Range located in Madison and Gallatin Counties, Montana and illustrates a region in southwest Montana with the northwest corner of Wyoming and the northern region of Yellowstone National Park appearing in the southeast quadrant of figure 1. The Madison River originates in Yellowstone National Park south of figure 1 and flows in a northwest direction to Hegben Lake (just west of Yellowstone National Park along the south edge of figure 1) and then flows in a west direction to Earthquake Lake before turning to flow in a north direction to Three Forks, Montana. At Three Forks the north oriented Madison River joins the north and northwest oriented Gallatin River and the northeast, east, and northeast oriented Jefferson River to form the north oriented Missouri River, which flows to the north center edge of figure 1. North of figure 1 the Missouri River turns to flow in a northeast and then east direction to North Dakota where it turns again to flow in a southeast and south direction with water eventually reaching the Gulf of Mexico. The Gallatin River originates in the northwest corner of Yellowstone National Park and flows in a northwest and north direction to Big Sky, Gallatin Gateway and near Manhattan before turning to flow again in a northwest direction to join the Madison and Jefferson River Rivers at Three Forks. The Madison Range is labeled in figure 1 and is located between the north oriented Madison and Gallatin Rivers. This essay investigates landform origins in the northern Madison Range area and a separate essays addresses landforms in the middle Madison Range area and in the northwest Yellowstone National Park region.

A brief big picture erosion history will help understand discussions related to detailed maps shown below. Large volumes of south and southeast oriented floodwaters once flowed across the region shown by figure 1. Floodwaters were derived from the western margin of a melting thick North American ice sheet and were flowing in a south and southeast direction from southwest Alberta and southeast British Columbia to and across the figure 1 region. North oriented rivers in figure 1, including the north oriented Madison, Gallatin, and Missouri Rivers, are generally flowing in valleys that originated as south oriented flood flow channels. When floodwaters first flowed across the region the mountain ranges, deep river valleys, and basins between the mountains did not exist and floodwaters could freely flow across the region. Mountain ranges emerged as floodwaters flowed across the region and initially floodwaters flowed across what are today high mountain ranges including the Madison Range. The Madison and Gallatin Rivers originated as a south oriented flood flow channels, which were subsequently reversed to form the north oriented drainage routes seen today. The flood flow reversal was probably indirectly caused by crustal warping that occurred as melt water floods flowed across the region with the crustal warping being related to the thick ice sheet presence north and east of figure 1, although the direct cause was headward erosion of a deep northeast oriented valley across Montana (north of figure 1), which beheaded the south oriented flood flow channel supplying floodwaters to the south oriented Madison and Gallatin River flood flow channels. The deep northeast oriented valley was eroding headward from space in the deep “hole” the melting ice sheet had occupied and was capturing the south and southeast oriented ice-marginal melt water floods and diverting the floodwaters into space in the deep “hole” the melting ice sheet had opened up. This northeast oriented valley was much deeper than the beheaded flood flow channels and floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented Missouri River segment and the north oriented Madison and Gallatin River drainage routes seen in figure 1.

Detailed location map for Madison River-Gallatin River drainage divide area

Figure 2: Detailed location map Madison River-Gallatin 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 Madison River-Gallatin River drainage divide area in the northern Madison Range located in Madison and Gallatin Counties, Montana and shows drainage routes not seen in figure 1. Green shaded areas are National Forest lands, which generally are located in mountainous regions. Three Forks, Montana is where the Madison, Gallatin, and Jefferson River meet to form the north oriented Missouri and is located near the north center edge of figure 2. The Madison River flows in a north direction from the south edge of figure 2 (west of center) to Ennis Lake and then in a north-northeast and north direction to Three Forks. The northern Madison Range is located east of Ennis Lake. Madison River tributaries originating in the northern Madison Range region include north-northwest oriented Pale Creek, northeast and northwest oriented Cherry Creek, and north, northwest, and west oriented Elk Creek. The northwest oriented Madison River tributary drainage routes originated as southeast oriented flood flow channels prior to headward erosion of the deep Madison River valley. Headward erosion of a deep south-oriented flood flow channel on the present day north oriented Madison River alignment captured the southeast oriented flood flow. Floodwaters on northwest ends of the beheaded flood flow channels reversed flow direction to create the northwest oriented drainage routes. The Gallatin River flows in a north-northeast and north-northwest direction from the south edge of figure 2 (east half) to near Spanish Breaks and then flows in roughly a north direction to near Bozeman Hot Springs and Manhattan before turning to flow in a northwest direction to join the Madison and Jefferson Rivers at Three Forks. Camp Creek is a north oriented stream originating near Spanish Breaks and joining the Gallatin River near Manhattan. Spanish Creek is formed at the confluence of its northeast oriented North Fork and north and north-northeast oriented South Fork and joins the Gallatin River in the Spanish Breaks region. Note northwest oriented Gallatin River tributaries from the east.

Camp Creek-Elk Creek drainage divide area

Figure 3: Camp Creek-Elk Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the Camp Creek-Elk Creek drainage divide area. This region is north of Madison Range and only a short distance south of Three Forks where the Madison and Gallatin Rivers meet. The Madison River flows from the southwest corner of figure 3 in a north direction to near the northwest corner of figure 3. The Gallatin River flows in a north-northwest direction across the northeast corner of figure 3. Elk Creek flows in a north direction from the south edge of figure 3 (west of center) to near the highway and then turns to flow in a west direction to join the north oriented Madison River near the southwest corner of figure 3. North of the west oriented Elk Creek segment is the labeled Madison Plateau. Camp Creek flows in a northwest direction from the south edge of figure 3 to the town of Anceney and then flows in a north and north-northeast direction to the north edge of figure 3 and joins the northwest oriented Gallatin River north of figure 3. Note how the highway west of Anceney is located in a through valley linking the west oriented Elk Creek valley segment with the north oriented Camp Creek valley. The map contour interval for figure 3 is 50 meters and the through valley floor elevation where the highway crosses the drainage divide is between 1450 and 1500 meters. The Madison Plateau to the north rises to more than 1600 meters and while not seen in figure 3 elevations south of figure 3 rise much higher suggesting the through valley is more than 100 meters deep. The through valley is a water-eroded feature and provides evidence of diverging and converging south oriented flood flow channels that once linked the Madison and Gallatin River valleys. Floodwaters initially flowed in a south and west direction from the Camp Creek valley to a south oriented flood flow channel on the present day north oriented Madison River valley alignment. Near Anceney a southeast oriented flood flow diverged from the southwest and west oriented flood flow channel and flowed in a southeast direction along the present day northwest oriented Camp Creek alignment to join a south oriented flood flow channel on the present day north oriented Gallatin River alignment. Following reversal of flood flow in the Madison and Gallatin River valleys floodwaters may have flowed in an east direction from the newly reversed Madison River valley to flow for a short period of time in a north direction a newly reversed flood flow channel on the Camp Creek alignment.

Detailed map of Camp Creek-Elk Creek drainage divide area

Figure 4: Detailed map of Camp Creek-Elk Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 4 provides a detailed topographic map of the Camp Creek-Elk Creek drainage divide area seen is less detail in figure 3. Anceney is the small community located in the east center region of figure 4. Elk Creek flows in a north direction from the forested valley near the south edge of figure 4 to the west center region of figure 4 and then turns to in a west-southwest direction to the west edge of figure (south of center) and joins the north oriented Madison River west of figure 4.  Camp Creek flows in a northwest direction from the east edge of figure 4 (south half) to near Anceney and then turns to flow in a north direction to the north edge of figure 4 and north of figure 4 joins the northwest oriented Gallatin River. The northwest and north oriented Camp Creek alignment was established by a south and southeast oriented flood flow channel that diverged and then converged with a southeast and south oriented flood flow channel on the present day north and northwest oriented Gallatin River alignment. South and southeast oriented flood flow on the Camp Creek alignment was probably reversed at the same time as southeast and south oriented flood flow on the Gallatin River alignment was reversed. The Gallatin River flood flow reversal was triggered by headward erosion of a deep northeast oriented valley from space in the deep “hole” the melting North American ice sheet had occupied, which beheaded a south oriented flood flow channel on the present day north oriented Missouri River alignment (north of Three Forks) which had been supplying floodwaters to the south oriented flood flow channels on the present day north oriented Madison River and Gallatin River alignments. Contributing significantly to the flood flow reversal was uplift of the Yellowstone Plateau region to the south and the emergence of the Madison Range and other regional mountain ranges. The crustal warping was directly and indirectly related to the thick ice sheet presence north and east of this essay’s study region.  Note the through valley in section 17 (northwest of Anceney) linking a north-northeast oriented Camp Creek tributary valley with a southwest oriented Elk Creek tributary valley. The map contour interval for figure 4 is 20 feet and the through valley floor elevation at the drainage divide is between 4780 and 4800 feet. The high point on the south end of the Madison Plateau near the north edge of the northwest quadrant of figure 4 reaches 5254 feet. Elevations along the south edge of figure 4 rise to more than 5400 feet suggesting the through valley is at 450 feet deep. The through valley was eroded by south, south-southwest, southwest, and west oriented flood flow moving from the present day north oriented Camp Creek alignment to a south oriented flood flow channel on the present day north oriented Madison River alignment.

Cherry Creek-Spanish Creek drainage divide area

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

Figure 5 illustrates the Cherry Creek-Spanish Creek drainage divide area south of figure 3 and does not include an overlap area with figure 3, although the gap between figures is small. The Gallatin River flows in northwest, north and north-northeast direction from the southwest corner of figure 5 to the east center edge of figure 5. The North Fork Spanish Creek flows in a northeast direction from the south center edge of figure 5 to Spanish Creek Basin and then flows in a west direction to join north-northeast oriented South Fork Spanish Creek and then joins the Gallatin River. Cherry Creek flows in a northeast direction from the near the southwest corner of figure 5 to Cherry Creek Basin and then turns to flow north direction through Cowboy Canyon and then to northwest oriented Cherry Creek Canyon and finally flows in a northwest direction to the north edge of figure 5 (west half). The East Fork Pole Creek originates near McCormack Pass (south of Cowboy Canyon) and flow in a north-northwest direction to the north edge of figure 5 (near northwest corner). North of figure 5 Pole Creek joins Cherry Creek, which then joins the north oriented Madison River. Elk Creek is the north, northwest, and north-northwest oriented stream originating south of Ruby Mountain and flowing to the north center edge of figure 5. Note how both Cherry Creek and the Gallatin River have eroded deep water gaps across mountain ridges, yet their valleys are linked by through valleys. The map contour interval for figure 5 is 50 meters and the through valley linking the Cherry Creek Basin with the Spanish Creek Basin has an elevation of between 1750 and 1800 at the drainage divide. Yet Cherry Creek has eroded a water gap across Elk Mountain, which exceeds 2000 meters in height and the Gallatin River has eroded an even deeper water gap across a ridge almost 2200 meters high. Mill Creek is a northwest oriented Cherry Creek tributary north of Finnegan Ridge and is linked by a through valley with southeast oriented streams flowing to Spanish Creek Basin. This through valley north and east of Finnegan Ridge has an elevation of between 1800 and 1850 meters at the drainage divide while Finnegan Ridge to the southwest rises to 2047 meters. Note also the through valley at McCormack Pass linking the north-northwest oriented Pole Creek valley with the north oriented Cherry Creek valley. These through valleys are water-eroded features and were eroded by southeast oriented flood flow moving to a southeast and south oriented flood flow channel on the present day northwest oriented Gallatin River alignment (in southeast corner of figure 5). The reversal of flood flow that created the north oriented Missouri, Madison, and Gallatin River drainage systems ended the southeast oriented flood flow across the region seen in figure 5 and created the drainage divides seen today.

Detailed map of Pole Creek-Cherry Creek drainage divide area

Figure 6: Detailed map of Pole Creek-Cherry 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 Pole Creek-Cherry Creek drainage divide area seen in less detail in figure 5. The East Fork Pole Creek originates just west of McCormack Pass in the southwest quadrant of section 34 and flows in northwest direction to join the Middle Fork and to form northwest and north-northwest oriented Pole Creek, which flows to the northwest corner of figure 6.  Cherry Creek flows in a north direction from the south edge of figure 6 (west of center) along the west side of Cherry Creek Basin and then through Cowboy Canyon to the north edge of figure 6. The East Fork Cherry Creek flows in a north direction from the south edge of figure 6 and then turns to flow along the northeast side of Cherry Creek Basin to join north oriented Cherry Creek in section 35. North and of figure 6 Cherry Creek turns to flow in a northwest direction to join the north oriented Madison River and Pole Creek joins Cherry Creek shortly before Cherry Creek enters the Madison River. McCormack Pass is a through valley linking the northwest and north-northwest oriented Pole Creek valley with the north oriented Cherry Creek valley. The map contour interval for figure 6 is 40 feet and the McCormack Pass elevation at the drainage divide is between 5800 and 5840 feet. Elk Mountain to the north rises to 6609 feet while an elevation of 7155 feet can be found near the west edge of figure 6 (north of southwest corner). These elevations suggest the McCormack Pass through valley is at least 850 feet deep. The McCormack Pass through valley and the Cowboy Canyon water gap were eroded by diverging and converging south and southeast oriented flood flow channels moving floodwaters from a south oriented flood flow channel on the present day north oriented Madison River alignment to a south oriented flood flow channel on the present day north oriented Gallatin River alignment. South and east of figure 6 the flood flow moved in the present day Spanish Creek valley (seen in figure 5), although before emergence of the Madison Range to the south the floodwaters may have continued in a southeast direction along what is now the northwest oriented Little Hell Roaring Creek alignment (seen in figures 9 and 10 below.

Madison River-Cherry Creek drainage divide area

Figure 7: Madison River-Cherry Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Madison River-Cherry Creek drainage divide area west and slightly south of figure 5 and includes a significant overlap area with figure 5. Ennis Lake is the reservoir straddling the south edge of figure 7 near the southwest corner of figure 7. The Madison River flows in a north-northeast and north direction from Ennis Lake through Bear Trap Canyon to the north edge of figure 7. Norris is a town located near the northwest corner of figure 7. Hot Springs Creek is an east oriented stream flowing through Norris and joins the north oriented Madison River slightly north of figure 7. West of figure 7 is the Gravelly Range, which is a high mountain range. Note how the highway west of the Madison River is located in a north-to-south oriented through valley linking a north oriented Hot Springs Creek tributary valley with south oriented valleys draining to Ennis Lake. The map contour interval for figure 7 is 50 meters and the through valley floor elevation where the highway crosses the drainage divide is between 1700 and 1750 meters. Elevations between the through valley and the north oriented Madison River valley rise to more than 1900 meters suggesting the through valley is more than 150 meters deep. The through valley was eroded by a diverging and converging south oriented flood flow channel prior to the reversal of flood flow in the Bear Trap Canyon valley. It is possible that for a time during the flood flow reversal process floodwaters moved south in the through valley and then made a U-turn to flow in a north direction in the newly reversed Bear Trap Canyon, where flood flow was probably reversed to flow in a north direction before the reversal of flood flow routes further to the west. Cherry Creek originates near Red Knob (east and slightly north of Ennis Lake) and flows in a northeast direction to the Cherry Creek Basin where it turns to flow in a north direction to Cowboy Canyon and the north edge of figure 7 (near northeast corner). North of figure 7 Cherry Creek turns to flow in a northwest direction to join the north oriented Madison River. North of Red Knob and west of the Cherry Creek headwaters note west-northwest oriented Rain Creek and northwest, southwest, and west oriented Fall Creek, which both flow directly to the north oriented Madison River. While they are subtle note how through valleys link the northwest oriented Fall Creek and the west northwest-oriented Rain Creek valleys with the northeast oriented Cherry Creek headwaters valley. The Fall Creek-Cherry Creek through valley floor elevation at the drainage divide is between 2250 and 2300 meters and the Rain Creek-Cherry Creek valley is 50 meters higher. Red Knob to the south rises to 2451 meters and a spot elevation to the north reads 2423 meters suggesting the through valleys are more than 100 meters deep. The through valleys were eroded by southeast oriented flood flow channels prior to erosion of the deep valleys to the west. At that time the Madison Range and the Gravelly Range had yet to emerge as mountain ranges and the deep Madison River valley did not exist so floodwaters could freely flow across the region. Headward erosion of a southwest oriented valley on the present day northeast oriented Cherry Creek alignment captured the southeast oriented flood flow first. As the mountain ranges emerged deep south-oriented flood flow channels, including the Madison River valley, eroded headward between the emerging mountain ranges and beheaded the flood flow to the southwest oriented flood flow channel. Continued emergence of the Madison Range caused a reversal of flow on the northeast end of the southwest oriented valley to create the northeast oriented Cherry Creek headwaters drainage route.

Detailed map of Fall Creek-Cherry Creek drainage divide area

Figure 8: Fall Creek-Cherry 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 Fall Creek-Cherry Creek drainage divide area seen in less detail in figure 7. The Madison River flows in a north-northeast and north direction from Ennis Lake (in southwest corner of figure 8) through Bear Trap Canyon to the north edge of figure 8 (near northwest corner). Fall Creek originates in the Cowboys Heaven area of section 22 and flows in a northwest direction to section 16 where it turns to flow in a southwest direction to join the north oriented Madison River. The map contour interval for figure 8 is 40 feet and elevations in the Madison River channel near the point in section 17 where Fall Creek joins it are approximately 4700 feet. Elevations at the Cowboy Creek headwaters are approximately 7400 feet, which means in a distance, which spans the equivalent of three one mile square sections, Fall Creek drops approximately 2700 feet. Cherry Creek flows in a northeast direction from the south center edge of figure 8 to the east edge of figure 8 (north half). A through valley seen in the west half of section 23 links the northwest oriented Fall Creek valley with the northeast oriented Cherry Creek valley. The through valley floor elevation at the drainage divide has an elevation of between 7440 and 7480 feet. Red Knob to the southwest in section 27 reaches an elevation of 8042 feet while an elevation of 8048 feet can be found just north of figure 8 suggesting the through valley may be more than 500 feet deep. While a relatively minor feature compared to the 2700-foot deep Bear Trap Canyon to the west the through valley is a water eroded feature and was eroded by southeast oriented flood flow prior to erosion of Bear Trap Canyon. The southeast oriented flood flow was captured by what probably originated as a southwest oriented flood flow channel on the Cherry Creek alignment. Note how the northeast oriented Cherry Creek valley is aligned with the southwest oriented St Joe Creek valley, with St Joe Creek flowing to the north oriented Madison River as a barbed tributary. A through valley in the northeast corner of section 34 and the southeast corner of section 27 links the northeast oriented Cherry Creek valley with the southwest oriented St Joe Creek valley. The through valley floor elevation at the drainage divide is between 7640 and 7680 feet, which suggests the through valley is approximately 360 feet deep. The southwest oriented flood flow channel was probably eroding headward from a south oriented flood flow channel on the present day north oriented Madison River alignment. At that time the high mountains seen in figure 8 had not emerged and the elevation differences that exist today did not exist. Note other south oriented streams or segments of streams flowing to the north oriented Madison River as barbed tributaries. These barbed tributaries provide further evidence of the flood flow reversal that created the north oriented Madison River drainage route.

South Fork Spanish Creek-Gallatin River drainage divide area

Figure 9: South Fork Spanish Creek-Gallatin River drainage divide. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the South Fork Spanish Creek-Gallatin River drainage divide area south and east of figure 7 and includes an overlap area with figure 7. Cherry Creek Basin is located at the northwest corner of figure 9. The Gallatin River flows in a north-northwest direction from near the southeast corner of figure 9 to the north edge of figure 9 (east half). The North Fork Spanish Creek flows in a northeast direction from the west center edge of figure 9 to near the north edge of figure 9 (at the Madison-Gallatin County line) and then turns to flow in an east direction to join north-northeast oriented South Fork Spanish Creek and to form east oriented Spanish Creek, which joins the north oriented Gallatin River near the north edge of figure 9. The South Fork Spanish Creek flows in a north-northeast direction from the south edge of figure 9 (west half, west of Blaze Mountain) to join the North Fork Spanish Creek near the north center edge of figure 9 and to form east oriented Spanish Creek. Little Hell Roaring Creek is a north and northwest oriented South Fork Spanish Creek tributary originating near the center of figure 9. Hell Roaring Creek is a northeast oriented Gallatin River tributary located east of Little Hell Roaring Creek and flowing from the south center edge of figure 9. North Fork Hell Roaring Creek originates near the south edge of figure 9 (west half, west of Gallatin Peak) and flows in a north, northeast, and southeast direction to join northeast oriented Hell Roaring Creek. An unlabeled southeast and east oriented Hell Roaring Creek tributary is located east of the Little Hell Roaring Creek headwaters. Note how that southeast and east oriented Hell Roaring Creek tributary is on the same alignment as the northwest oriented Little Hell Roaring Creek valley segment, which was also on the same alignment as the northwest oriented Pole Creek valley seen in figure 5. As described in the figure 5 discussion this alignment was probably initiated by a southeast oriented flood flow channel and was subsequently dismembered as the Madison Range emerged and deep valleys eroded headward into the region. While no pass or through valley is visible on the Little Hell Roaring Creek-Hell Roaring Creek drainage divide in figure 9, the map contour interval for figure is 50 meters and a pass may be present, but is just not deep enough to show up on the map. Note how a high pass does link the north oriented Little Hell Roaring Creek headwaters valley with the North Fork Hell Roaring Creek valley at the elbow of capture where it turns from being a northeast oriented valley to being a southeast oriented valley. The pass or through valley elevation at the drainage divide is between 2700 and 2750 meters. The high point east of the pass reaches 2826 meters suggesting the pass is at least 76 meters deep. While not deep compared to the surrounding valleys the pass is evidence of a former south oriented flood flow channel location.

Detailed map of Little Hell Roaring Creek-Hell Roaring Creek drainage divide area

Figure 10: Detailed map of Little Hell Roaring Creek-Hell Roaring 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 Little Hell Roaring Creek-Hell Roaring Creek drainage divide area seen in less detail in figure 9. Little Hell Roaring Creek originates in the northeast quadrant of section 11 (near center of figure 10) and flows in a northeast and north direction into section PB 38 where it turns to flow in a northwest direction to the northwest corner of figure 10. Hell Roaring Creek flows in a northeast and north-northeast direction from the south edge of figure 10 (east of center) to the northeast corner of figure 10. The North Fork Hell Roaring Creek flows in northeast and east direction from the south edge of figure 10 into section PB 45 where it turns to flow in a southeast direction to join northeast oriented Hell Roaring Creek as a barbed tributary. An east and southeast oriented Hell Roaring Creek tributary has eroded a significant east oriented valley in sections PB 44 and 7 east of the Little Hell Roaring Creek headwaters. Interpretations in this region are complicated by evidence that the heads of the Little Hell Roaring Creek and the North Fork Hell Roaring Creek valleys were probably altered by glacial erosion. If so the valleys predated the glaciation, which occurred long after flood flow across the region ended and the Madison Range had emerged as a high mountain range. There is a dip in the narrow ridge that forms the Little Hell Roaring Creek-Hell Roaring Creek drainage divide in northwest quadrant of section PB 44. The map contour interval for figure 10 is 40 feet and the lowest elevation on the narrow ridge is between 8880 and 8920 feet. The high point on the ridge to the north in section PB 37 is 8990 feet and the high point to the south in section PB 44 is 9270 feet. These elevations suggest the dip in the ridge may be evidence of a flood flow channel 70 to 110 feet deep. In this case other interpretations for the origin of the dip are possible. Evidence for a more convincing flood flow channel can be seen in the Arrow Lake valley in the east half of section 11. The Arrow Lake valley links the north oriented Little Hell Roaring Creek headwaters valley with the southeast oriented North Fork Hell Roaring Creek valley segment. The elevation at Arrow Lake is between 9000 and 9040 feet. To the east elevations rise to 9270 feet and to the west elevations rise much higher suggesting the Arrow Lake through valley is at least 230 feet deep. The Arrow Lake through valley was eroded by southeast and/or south oriented flood flow prior to the emergence of the Madison Range as a high mountain range. At that time elevations north of figure 10 were just as high as elevations in the region illustrated in figure 10. Since that time the Madison Range has emerged, with headward erosion of deep valleys into what was probably a rising mountain mass with the crustal warping being directly and indirectly related to the presence of a thick North American ice sheet north and east of this essay’s study region.

Additional information and sources of maps studied

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

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