Ruby River-Madison River drainage divide area landform origins in the Gravelly Range, Madison County, Montana, USA

Authors


Abstract:

This essay uses topographic map evidence to interpret landform origins between the Ruby River and the Madison River in the Gravelly Range, Madison County, Montana. The Gravelly Range is located south of the Tobacco Root Mountains between the north oriented Madison and Ruby River valleys. The Madison River is east of the Gravelly Range while the Ruby River is west of the Gravelly Range and flows to the north-northeast, southeast, and northeast oriented Jefferson River, which north and east of the Tobacco Root Mountains joins the north oriented Madison River and north and northwest oriented Gallatin River to form the north oriented Missouri River. Southeast oriented streams flow to the north oriented Madison River as barbed tributaries while south and southwest oriented streams flow to the north oriented Ruby River as barbed tributaries. Alder Gulch originates as a north and northwest oriented drainage route east of the Gravelly  Range and turns to drain in west direction through the deep gap between the Tobacco Root Mountains and the Gravelly Range to join a northwest oriented Ruby River segment. Through valleys or mountain passes link west oriented Ruby River tributary valleys with east oriented Madison River tributary valleys. Examples of these types of erosional landforms are illustrated and interpreted to be evidence of south and southeast oriented flood flow channels that crossed the region prior to the emergence of the Gravelly Range as the high mountain range it is today. At that time the Ruby River valley did not exist, the Gravelly Range and Tobacco Root Mountains had yet to emerge and a deep south oriented flood flow channel was eroding headward along the present day north oriented Madison River alignment. Floodwaters are interpreted to have been derived from the western margin of a thick North American ice sheet and were flowing in south and southeast directions from western Canada across the study region. Crustal warping related to the thick ice sheet presence, flood water erosion and deposition, plus headward erosion of deep south-oriented flood flow channels were responsible for initial emergence of the Gravelly Range. Headward erosion of a south oriented valley on the Ruby River alignment followed headward erosion of a south oriented valley on the Madison River alignment and captured southeast oriented flood flow moving across the emerging Gravelly Range. Floodwaters on northwest and west ends of beheaded flood flow channels reversed flow direction create northwest and west oriented Ruby River tributary drainage routes. South oriented flood flow on the Madison River alignment was beheaded and reversed by headward erosion of a much deeper northeast oriented valley across a south oriented flood flow channel supplying floodwaters to the south oriented Madison River flood flow channel. The much deeper valley eroded 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 flood flow. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the present north oriented Missouri River route north of Three Forks and the north oriented Madison and Gallatin River routes south of Three Forks while headward erosion of the deep  Jefferson River valley  beheaded south oriented flood flow channel supplying floodwaters to the south oriented Ruby River flood flow channel and floodwaters on the north end of the beheaded flood channel reversed flow direction to create the north oriented Ruby River drainage route.

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 Ruby River-Madison River drainage divide area landform origins in the Gravelly Range, Madison County, 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 Ruby River-Madison River drainage divide area landform evidence in the Gravelly Range, Madison County, Montana will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Ruby River-Madison River drainage divide area location map

Figure 1. Ruby River-Madison 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 Ruby River-Madison River drainage divide area in the Gravelly Range, Madison County, Montana and primarily illustrates a region in southwest and south central Montana with the northwest corner of Wyoming and Yellowstone National Park in the southeast corner of figure 1 and west of Yellowstone National Park a strip of Idaho is located along the south edge of figure 1. The Madison River originates east of the town of West Yellowstone, Montana and flows in a northwest direction to Hebgen Lake and then in a west direction to Earthquake Lake before turning to flow in a north-northwest direction to Ennis, Montana. From Ennis the Madison River flows in a north-northeast and north direction to Three Forks where it joins the north and northwest Gallatin River and the north-northeast, east, and northeast oriented Jefferson River to form the north oriented Missouri River. The Ruby River is shown, but is not labeled in figure 1 and is the unlabeled river west of the Madison River flowing from the Hogback Mountain area to the towns Alder and Laurin before joining the north-northeast oriented Beaverhead River and the south and northeast oriented Big Hole River near Twin Bridges to form the north-northeast, east, and northeast oriented Jefferson River. The Gravelly Range is not labeled in figure 1, but is the mountain range found between the north-oriented Ruby and Madison Rivers and is located south of the Tobacco Root Mountains. The Ruby River-Madison River drainage divide area in the Gravelly Range in Madison County, Montana illustrated and discussed in this essay is generally located south of the Tobacco Root Mountains, west of the Madison River, and east of the Ruby River. The Jefferson River-Madison drainage divide area in Madison and Gallatin Counties and the Jefferson River-South Boulder River drainage divide area in the Tobacco Root Mountains essays illustrate and describe areas directly north of this essay’s study region and the West Fork Madison River-Red Rock River drainage divide area in Beaverhead and Madison Counties and the Ruby River-Red Rock River drainage divide area in Beaverhead and Madison Counties essays illustrate and discuss regions directly south of this essay’s study region.

A brief look at the 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 western Canada to and across the figure 1 region. North oriented rivers in figure 1, including the north oriented Missouri, Madison, Gallatin, and Ruby Rivers are flowing in valleys that originated as south oriented flood flow channels. When floodwaters first flowed across the region the present day mountain ranges did not exist and floodwaters could freely flow in south and southeast directions across the region. The mountain ranges emerged as floodwaters flowed across the region and initially floodwaters flowed across what are today high mountains including the Gravelly Range. More successful, or deeper, flood flow channels moving floodwaters across mountain ranges first captured floodwaters from adjacent less successful flood flow channels and later floodwaters were captured by flood flow channels moving floodwaters between the emerging mountain ranges. These captures of the south and southeast oriented flood flow channels initially were made by the headward erosion of other southeast or southwest oriented valleys across the less successful, or shallower, south or southeast oriented flood flow channels. Through valleys or mountain passes crossing present-day drainage divides today provide evidence of the former flood flow channels. Segments of the present day north oriented Jefferson River valley probably were initiated by the headward erosion of south-southwest oriented and/or southwest oriented valleys across south and southeast oriented flood flow routes and may have beheaded and reversed flood flow in the Ruby River valley. As mountain ranges emerged a much more massive flood flow reversal occurred, which systematically reversed flood flow in most, but not all of the south oriented flood flow channels in the southwest Montana Missouri River drainage basin to create the drainage routes seen today.

The flood flow reversal that created the present day north oriented Missouri, Madison, Gallatin, and Jefferson Rivers was indirectly caused by crustal warping that occurred as melt water floods flowed across the region with the crustal warping being related to thick ice sheet presence north and east of figure 1 and probably to the flood water erosion and deposition, although the direct cause was headward erosion of a deep northeast oriented valley across Montana (the northeast oriented Missouri River valley north of figure 1), which beheaded the south oriented flood flow channel supplying floodwaters to a south oriented Missouri River flood flow channel on the present-day north  and north-northwest oriented Missouri River alignment. At Three Forks, Montana this south oriented flood flow channel had split into several diverging south oriented flood flow channels. The deep northeast oriented valley (now the northeast oriented Missouri River valley north of figure 1) 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 captured floodwaters into space being opened up in the deep “hole” where the melting the ice sheet had been located. This northeast oriented valley was much deeper than the beheaded south oriented flood flow channel and floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the north oriented Missouri River drainage route and tributary drainage routes seen in figure 1. The reversal of flow in the Missouri River flood flow channel also reversed flood flow in flood flow channels on the Gallatin and Madison River alignments to create the north oriented Madison and Gallatin River drainage routes seen today. Headward erosion of a deep northeast and east oriented Jefferson River valley from this reversed Missouri River flood flow channel next beheaded flood flow channels further to the west and floodwaters on north ends of those beheaded flood flow channels reversed flow direction to create north oriented drainage routes, including the north-northeast oriented Jefferson River drainage route, which beheaded and reversed flood flow on the Ruby River alignment to the create the north and northwest oriented Ruby River drainage route seen today, although the history includes many complexities not given in this brief description.

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

Figure 2: Detailed location map Ruby River-Madison River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 2 provides a more detailed location map for the Ruby River-Madison River drainage divide area in the Gravelly Range, Madison County, Montana and shows drainage routes not seen in figure 1. Green shaded areas are National Forest lands, which generally are located in mountainous regions. County boundaries are shown and Madison County is labeled. The reservoir in the southeast corner of figure 2 is Hebgen Lake, which floods the northwest oriented Madison River valley. Downstream from Hebgen Lake the Madison River flows in a west-southwest direction through Earthquake Lake to near the town of Cliff where the Madison River turns to flow in a north-northwest and north direction to Ennis and then to the north edge of figure 2 (east of center). Named Madison River tributaries from the west include southeast oriented Moore Creek, southeast and northeast oriented Wigwam Creek, northeast oriented Morgan Creek, north and northeast oriented Ruby Creek, east-southeast and east-northeast Horse Creek, east-southeast and east-northeast oriented Standard Creek, and the southeast oriented Elk River, which flows to the northeast oriented West Fork Madison River. The Gravelly Range is located west of the north oriented Madison River valley. The Ruby River originates near the south edge of figure 2 (west of center) and flows in a north, northwest, and north direction on the west side of the Gravelly Range to Ruby River Reservoir. Downstream from Ruby Dam the Ruby River flows in a north and northwest direction near the towns of Alder and Laurin to the north edge of figure 2 (west half). Alder Gulch is the unnamed north, northwest, and west oriented tributary flowing through Virginia City and joining the Ruby River near the town of Alder. Granite Creek is the named southwest oriented Alder Gulch tributary north of Virginia City. Warm Springs Creek is the unlabeled south oriented stream near the center of figure 2 and is joined by the unlabeled west oriented Middle Fork and unlabeled northwest oriented South Fork before flowing to join the Ruby River at the point where the Ruby River turns from flowing in a north direction to flowing in a northwest direction. South of unlabeled Warm Springs Creek is unlabeled northwest oriented Cottonwood Creek and south of Cottonwood Creek is the labeled west-northwest oriented East Fork Ruby River. North oriented drainage routes, which dominate the figure 2 region, are generally flowing in valleys initiated as south oriented flood flow channels and were created by the massive flood flow reversals described in the figure 1 discussion. Northwest oriented drainage routes were created by reversals of flood flow northwest ends of beheaded southeast oriented flood flow channels. South and southeast oriented drainage routes seen in figure 2 are relics of south and southeast oriented flood flow channels that once crossed the entire region seen in figure 2.

Granite Creek-Moore Creek drainage divide area

Figure 3: Granite Creek-Moore 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 Granite Creek-Moore Creek drainage divide area. The town of Ennis is located near the southeast corner of figure 3. The Madison River flows in a north-northeast direction from the south edge of figure 3 (south of Ennis) to Ennis Lake near the northeast corner of figure 3 (Ennis Lake is a reservoir flooding the Madison River valley). Figures 7 and 8 in the Jefferson River-Madison River drainage divide area essay illustrate and describe the region north of figure 3. The southeast edge of the Tobacco Root Mountains can be seen in the northwest quadrant of figure 3. Moore Creek is a southeast oriented stream joining the north oriented Madison River as a barbed tributary near the town of Ennis. Granite Creek is the southwest oriented stream flowing to the southwest corner of figure 3 and west of figure 3 joins north and northwest Alder Gulch, which then drains in a west direction to the north oriented Ruby River. Note the multiple south-southwest and south oriented tributaries which flow to southwest oriented Granite Creek. Looking at the south oriented drainage routes in figure 3 it is difficult to imagine this region is today in the north oriented Missouri River drainage basin. South Meadow Creek is the east oriented stream flowing near the north edge of figure 3 to Ennis Lake. Northeast oriented Virginia Creek is a South Meadow Creek tributary on the same alignment as south-southwest oriented East Fork Granite Creek. The northeast oriented Virginia Creek valley and the south-southwest oriented East Fork Granite Creek valley are linked by a through valley. The map contour interval for figure 3 is 50 meters and the through valley floor elevation is slightly lower than 2250 meters. Elevations to the east rise to approximately 2350 meters while elevations to the west rise even higher. If correctly interpreted the through valley is approximately 100 meters deep. The through valley is a water-eroded feature and was eroded by southwest oriented flood flow moving to the west oriented Alder Gulch valley and then to what was once a south oriented flood flow channel on the present day north oriented Ruby River alignment. Nearby another shallower through valley links the south-southwest oriented East Fork Granite Creek valley with the southeast oriented Moore Creek valley. This shallow through valley suggests headward erosion of the south-southwest oriented East Fork Granite Creek valley beheaded southeast oriented flood flow moving to the southeast oriented Moore Creek valley. This sequence of events is consistent with headward erosion of a deep south-oriented flood flow channel on the present day north oriented Madison River route. Headward erosion of the south-southeast oriented East Fork Granite Creek valley first captured and beheaded southeast oriented flood flow to the southeast oriented Moore Creek valley, which was eroding headward from the actively eroding south oriented flood flow channel on the Madison River alignment. Next headward erosion of the deep east oriented South Meadow Creek valley from the actively eroding south oriented flood flow channel on the Madison River alignment captured the south-southwest oriented flood flow and beheaded the flood flow to the East Fork Granite Creek valley. Floodwaters on the northeast end of the beheaded flood flow route reversed flow direction to create the northeast oriented Virginia Creek drainage route. Similar sequences of events were repeated countless times as deeper flood flow channels captured floodwaters flowing to less deep flood flow channels and the south oriented drainage routes seen in figure 3 are relics of south oriented flood flow channel routes that were captured when deeper flood flow channels reversed flow direction to flow in a north direction to the much deeper northeast oriented Missouri River valley, which eroded headward from space in the deep “hole” being opened up by the melting ice sheet.

Detailed map of East Fork Granite Creek-Moore Creek drainage divide area

Figure 4: Detailed map of East Fork Granite Creek-Moore 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 East Fork Granite Creek-Moore Creek drainage divide area seen is less detail in figure 3. The East Fork Granite Creek originates in the southeast corner of section 5 (northwest quadrant of figure 4) and flows in a south-southwest direction to the south edge of figure 4 (near southwest corner) with water flowing to west oriented Alder Gulch and then to the northwest and north oriented Ruby River. Virginia Creek originates in the north half of section 4 and flows in a northeast direction to the north center edge of figure 4 and joins east oriented South Meadow Creek north of figure 4 with water flowing to the north oriented Madison River. The “Prospect” near the west edge of section 4 is located in a through valley linking the northeast oriented Virginia Creek valley with the south-southwest oriented East Fork Granite Creek valley. The map contour interval for figure 4 is 40 feet and the through valley floor elevation at the “Prospect” location is between 7360 and 7400 feet. Elevations in the south half of section 4 rise to more than 7720 feet while elevations west of the through valley in section 5 rise to more than 7840 feet suggesting the through valley is at least 320 feet deep. Moore Creek originates in section 9 (south of section 4) and flows in a south-southeast direction to the south edge of figure 4 (west of center) with water eventually reaching the north oriented Madison River.  A through valley along the boundary between sections 8 and 9 links the south-southwest oriented East Fork Granite Creek valley with the south-southeast oriented Moore Creek valley. The through valley floor elevation at the drainage divide is between 7320 and 7360 feet. The drainage divide in the northeast quadrant of section 17 to the south rises to 7530 feet and to the north the drainage divide rises more than 7720 feet near the south margin of section 4. These elevations suggest the through valley is 170 feet deep. Depths of the through valleys are consistent with those determined from the less detailed map in figure 3. The figure 3 map discussion described how the through valleys were formed. These through valleys are small examples of the through valleys seen throughout the study region and which provide evidence of flood flow channels, which were beheaded by headward erosion of deeper flood flow channels as deep valleys eroded headward into the region. At the same time as deep valleys eroded headward into the region the regional mountain ranges were being uplifted, which further contributed to flood flow capture events.

Alder Gulch-Moran Creek drainage divide area

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

Figure 5 illustrates the Alder Gulch-Moran Creek drainage divide area south and slightly west of figure 3 and includes an overlap area with figure 3. The town of Ennis is located near the northeast corner of figure 5. The Madison River flows in a north direction near the east edge of figure 5. Alder Gulch flows in a north, north-northwest, northwest, and west direction from the south edge of figure 5 (west half) to the towns of Summit and Virginia City to the west edge of figure 5 (near northwest corner). Granite Creek is the southwest oriented stream joining the west oriented Alder Gulch valley near the northwest corner of figure 5. The north end of the Gravelly Range can be seen in the southwest quadrant of figure 5. At first glance drainage routes in figure 5 appear to be consistent with a north oriented drainage system, however with closer inspection some problems arise. Perhaps the most serious problem is the north, north-northwest, and northwest oriented Alder Gulch headwaters are located on the east side of the Gravelly Range and then turn to drain in a west direction through the deep gap between the Tobacco Root Mountains to the north and the Gravelly Range to the south to join the northwest and north oriented Ruby River. The map contour interval for figure 5 is 50 meters and the valley floor where Granite Creek joins Alder Gulch near the northwest corner of figure 5 has an elevation of less than 1700 meters. The Tobacco Root Mountains to the north rise to more than 3100 meters while the Gravelly Range to the south rises to more than 3100 meters. In other words Alder Gulch is flowing west in a large valley between the two mountain ranges that is more 1400 meters deep. Geologic structures responsible for forming the mountain ranges probably played a significant role in forming the present day west oriented valley, yet running water also eroded the valley. The west oriented Alder Gulch valley probably was initiated as a southeast oriented flood channel moving floodwaters to south oriented flood flow channels seen in figure 5. The most obvious of these south oriented flood flow channels was located on the present day north oriented Madison River alignment. However a less obvious south oriented flood flow channel was located on the present day north oriented Alder Gulch headwaters alignment, although southeast oriented flood flow channels diverged from that south oriented flood flow channel. Floodwaters from these diverging southeast oriented flood flow channels were captured by headward erosion of much deeper northeast oriented valleys from the newly reversed flood flow channel on the Madison River alignment (e.g. Moran Creek, which originates in the south center region of figure 5). The south oriented flood flow channel on the Alder Gulch alignment was beheaded and reversed when headward erosion of a much deeper flood flow channel on the Ruby River alignment reversed the southeast and east oriented flood flow moving between the mountains ranges to create the north and west oriented Alder Gulch drainage route seen today. The reversal of flood flow also reversed flood flow on northwest ends of southeast oriented flood flow channels diverging from what had been the south oriented Alder Gulch flood flow channel and created present day northwest oriented Alder Gulch tributary drainage routes (e.g. Daylight Creek, which joins Alder Gulch near Virginia City).

Detailed map of Butcher Gulch-Moran Creek drainage divide area

Figure 6: Detailed map of Butcher Gulch-Moran 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 Butcher Gulch and Moran Creek drainage divide area seen in less detail in figure 5. Alder Gulch drains in a north-northeast and north-northwest direction from the southwest corner region of figure 6 to the northwest corner of figure 6. North and west of figure 6 Alder Gulch drains in a west direction to join the northwest, north, and northwest oriented Ruby River. Butcher Gulch is a north-northeast and northwest oriented Alder Gulch tributary in the northwest quadrant of figure 6. Moran Creek originates near the center of figure 6 and flows in an east-northeast direction to the east edge of figure 6 (north half) and east and north of figure 6 joins the north oriented Madison River. A through valley near Grassy Lake links the northwest oriented Butcher Gulch valley with an east oriented Moran Creek headwaters valley. The map contour interval for figure 6 is 40 feet and the through valley floor elevation (near southwest corner of section 5) is between 7120 and 7160 feet. The ridge immediately to the north rises to more than 7400 feet and the slope south of Grassy Lake rises even higher suggesting the through valley is at least 240 feet deep. The through valley was eroded by southeast and east oriented flood flow diverging from south oriented flood flow on the Alder Gulch alignment and then flowing to a flood flow channel on the Madison River. The through valley was probably eroded about the time the massive flood flow reversals were taking place and may have first delivered flood flow to a south oriented flood flow channel, but later was captured by headward erosion of the deeper northeast oriented Moran Creek valley (east of figure 6) which was eroding from the newly reversed Madison River flood flow channel. The flood flow reversals were not instantaneous and often floodwaters moved in a south direction in one flood flow channel only to be captured and diverted to flow in a north direction in an adjacent flood flow channel. The reversal of flood flow on the Alder Gulch alignment also reversed flood flow on the Butcher Gulch alignment to create the drainage routes seen today. Again this description is simplistic as each valley segment was created by independent captures and reversal events, but this description provides an outline to help future researchers who want to work out more complete histories. It is important to remember when doing so that crustal warping was raising mountain ranges and perhaps lowering elevations in adjacent valleys and basins as these flood flow captures and reversals were taking place.

Alder Gulch-Wigwam Creek drainage divide area

Figure 7. Alder Gulch-Wigwam Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Alder Gulch-Wigwam Creek drainage divide area south and east of figure 5 and includes a significant overlap area with figure 5. The Madison River flows in a north-northwest and north direction near the east edge of figure 7. Summit is a place-name in the northwest quadrant of figure 7 and Alder Gulch drains in a north-northeast direction through Summit to the north edge of figure 7. North of figure 7 Alder Gulch turns to drain in a northwest and west direction to join the northwest, north, and northwest oriented Ruby River. North oriented drainage routes flowing to the north edge of figure 7 west of Alder Gulch are Alder Gulch tributaries and west oriented drainage routes flowing the west edge of figure 7 are Ruby River tributaries. South and southwest oriented drainage routes in the southwest corner region of figure 7 are also tributaries to the north, northwest, north, and northwest oriented Ruby River. Wigwam Creek originates with southeast oriented headwaters south of the north oriented Alder Gulch headwaters and then turns abruptly to flow in a northeast direction across the center of figure 7 to join the north oriented Madison River. In addition to the southeast oriented Wigwam Creek headwaters Wigwam Creek has other southeast or south-southeast oriented tributaries including Buffalo Creek and its tributary Arasta Creek. The elbows of capture where the northeast oriented Wigwam Creek valley has captured its southeast and south-southeast oriented headwaters provide evidence the northeast oriented Wigwam Creek valley eroded headward from the deep Madison River valley to capture diverging and converging south and southeast oriented flood flow channels such as might be founds in an anastomosing channel complex. The south and southeast oriented floodwaters captured by headward erosion of the northeast oriented Wigwam Creek valley had to flow across what is now the deep west oriented Alder Gulch valley in the gap between the Gravelly Range to the south and the Tobacco Root Mountains, which means that valley or gap between the mountain ranges did not exist at that time and has formed since headward erosion of the northeast oriented Wigwam Creek valley captured the southeast oriented flood flow. If correctly interpreted this observation means the Gravelly Range and Tobacco Root Mountains emerged as floodwaters were flowing across the region. Emergence of the mountain ranges was probably caused by ice sheet related crustal warping, which included crustal warping caused by deep flood erosion of mountain core areas and by deposition of flood eroded and transported debris in adjacent valleys and basins. Also headward erosion of deep flood flow channels into the emerging mountain masses contributed to the formation of the mountain ranges seen today.

Wigwam Creek-Warm Springs Creek drainage divide area

Figure 8: Wigwam Creek-Warm Springs Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates the Wigwam Creek-Warm Springs Creek drainage divide area south and west of figure 7 and includes a significant overlap area with figure 7. The Ruby River flows in a northwest direction across the southwest quadrant of figure 8. Note southwest oriented Ruby River tributaries, which include Greenhorn Creek, Willows Creek, and Ice Creek. Also note south oriented tributaries, which include Timber Creek, Davis Creek, and Warm Springs Creek with its south and southwest oriented French Gulch tributary. All of these south oriented tributaries flow to the northwest and north oriented Ruby River as barbed tributaries and provide evidence of the south oriented flood flow channels that once crossed the region. The high northwest-to-southeast Gravelly Range crest ridge is labeled and extends from the north edge of figure 8 to near the southeast corner of figure 8. North and east of the Gravelly Range crest ridge are headwaters of northeast and east oriented Madison River tributaries. Wigwam Creek can be seen flowing in a southeast and then northeast direction near the north edge of figure 8 (east half). While they are subtle through valleys crossing the Gravelly Range crest ridge link the Wigwam Creek valley with the south oriented Warm Springs Creek valley and also with the south the south oriented French Gulch valley. These through valley appear as low areas along the Gravelly Range crest ridge. The map contour interval for figure 8 is 50 meters and elevations on the floors of the through valleys are between 2500 and 2550 meters. Elevations north of the through valleys rise to more than 2850 meters while south of the through valleys elevations in figure 8 rise to more than 2700 meters and south of figure 8 elevations rise to 2875 meters. Between the through valleys elevations rise to 2625 meters. Depending on which elevations are used and how the through valleys are defined the through valleys could be considered to be anywhere from 75 meters to 300 meters deep. The through valleys are probably water-eroded landforms and were eroded at a time when south oriented flood flow channels were being eroded into a surface equivalent in elevation to the elevation of the Gravelly Range crest ridge today. At that time there were no deep Madison and Ruby River valleys and the Gravelly Range and other regional mountain ranges had yet to emerge as high mountain ranges.

Cottonwood Creek-Standard Creek drainage divide area

Figure 9: Cottonwood Creek-Standard Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the Cottonwood Creek-Standard Creek drainage divide area south and slightly east of figure 7 and does not include an overlap area with figure 8, although the gap between figures 8 and 9 is very small. The Ruby River flows in a north-northeast direction from near the southwest corner of figure 9 to the north edge of figure 9 (near northwest corner) and north of figure 9 turns to flow in a northwest direction. The northwest oriented “South Fork” seen east of the Ruby River near the north edge of figure 9 is the South Fork of Warm Springs Creek, which was the south and west oriented Ruby River tributary seen in figure 8. The high Gravelly Range crest ridge extends in north-to-south direction near the center of figure 9. West of the Gravelly Range crest ridge Ruby River tributaries are generally are oriented in northwest directions while east of the Gravelly Range crest ridge Madison River tributaries in the northeast quadrant of figure 9 are generally oriented in northeast directions while further to the south the Madison River tributaries are generally oriented in southeast directions or have significant southeast oriented segments. Study of the Gravelly Range crest ridge reveals through valleys linking the Ruby River tributary valleys with the Madison River tributary valleys (or linking Madison River tributary valleys with other Madison River tributary valleys). The best example of such a linkage is found between Big Horn Mountain and Black Butte on the Gravelly Range crest ridge and links the west-northwest oriented Cottonwood Creek valley with the east-southeast oriented Standard Creek valley. The map contour interval for figure 9 is 50 meters and the through valley elevation at the drainage divide is between 2700 and 2750 meters. Black Butte to the south rises to 3214 meters while Monument Ridge to the north rises to at least 2900 meters and Big Horn Mountain to the east of Monument Ridge rises to 3132 meters suggesting the through valley may be as much as 280 meters deep. Note how through valleys across the ridge linking Monument Ridge, Big Horn Mountain, and Cave Mountain link Horse Creek tributary valleys with the east-southeast oriented Standard Creek valley. These through valleys provide further evidence of diverging and converging flood flow channels that once eroded the high-level Gravelly Range surface. Remember at that time the deep Madison and Ruby River valleys did not exist and the Gravelly Range had yet to emerge as a high mountain range so floodwaters could flow across the region.

Detailed map of Cottonwood Creek-Standard Creek drainage divide area

Figure 10: Detailed map of Cottonwood Creek-Standard 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 Cottonwood Creek-Standard Creek drainage divide area seen in less detail in figure 9. Black Butte is the labeled high point in the southwest quadrant of figure 10 and rises to 10,542 feet (the contour interval for figure 10 is 40 feet). Big Horn Mountain is the labeled high point in the northeast quadrant of figure 10 and rises to 10,275 feet. Standard Creek flows in a southeast direction south of Big Horn Mountain and east of figure 10 joins the north oriented Madison River. Cottonwood Creek originates north of Black Butte and flows in a west-northwest direction to the west edge of figure 10 (north half) and west of figure 10 joins the north and northwest Ruby River. In section 34 near the center of figure 10 a through valley links the west-northwest oriented Cottonwood Creek valley with the southeast oriented Standard Creek valley. The elevation at the road intersection on the through valley floor has an elevation of 8935 feet. Using the elevations of Black Butte and Big Horn Mountain as the adjacent high points the through valley may be as much 1300 feet deep. Regardless of how deep the through valley is the through valley is evidence of a southeast oriented flood flow channel that once crossed the Gravelly Range. At that time there was no deep Ruby River valley to the west and floodwaters could flow in a southeast direction to the southeast oriented Standard Creek valley alignment and then to a south oriented flood flow channel on the present day north oriented Madison River alignment. Horse Creek flows in a southeast direction across the northeast corner of figure 10 and is joined by northeast and east oriented Alpine Creek at the northeast corner of figure 10. East of Big Horn Mountain is northeast oriented Deer Creek, which joins Horse Creek east of figure 10. Note through valleys eroded on either side of Big Horn Mountain linking the Alpine Creek and Deer Creek valleys with the Standard Creek valley. While today those through valleys are little more than mountain passes they provide evidence of diverging and converging flood flow channels that were eroded into the high-level Gravelly Range surface. Remember, at that time a deep south oriented flood flow channel was eroding headward on the present day north oriented Madison River alignment, the Ruby River valley west of figure 10 did not exist, and the Gravelly Range had yet to emerge as the high mountain range it is today.

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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