Abstract:

The Gallatin River-Yellowstone River drainage divide area in the northern Gallatin Range discussed here is located in south central Montana a short distance north of Yellowstone National Park and this essay interprets landform origins using topographic map evidence. The Gallatin Range is located between the north-northwest and north oriented Gallatin River to the west and the northwest and north-northeast oriented Yellowstone River to the east and extends from the Yellowstone National Park northwest corner in Wyoming to the Bridger Range in Montana. Northwest and west oriented Gallatin River tributary valleys are linked by through valleys with southeast and east oriented Yellowstone River tributary valleys. The through valleys provide evidence of multiple southeast oriented flood flow channels to what at one time was a major south and southeast oriented flood flow channel on the present day northwest and north-northeast oriented Yellowstone River valley alignment. Floodwaters were derived from a rapidly melting thick North American ice sheet, which was located in a deep “hole.” Headward erosion of a deep south and south-southeast oriented flood flow channel on the present day north-northwest and north oriented Gallatin River alignment beheaded and reversed the southeast oriented flood flow to the south oriented Yellowstone River flood flow channel. The southeast oriented flood flow channels beheading and reversals were greatly aided by Gallatin Range uplift, which occurred as floodwaters were flowing across the region. Yellowstone Plateau uplift, which also was occurring as south and southeast oriented floodwaters flowed across it, combined with headward erosion of the deep east and northeast oriented Yellowstone River valley (from space in the deep “hole” the melting ice sheet had once occupied), resulting in the beheading and reversal of the south-southwest and southeast oriented Yellowstone River flood flow channel. Subsequently Yellowstone Plateau uplift and headward erosion of the deep northeast and east oriented Missouri River valley north and west of the newly eroded Yellowstone River valley (also from space in the deep “hole’) resulted in the beheading and reversal of the south and south-southeast oriented Gallatin River flood flow channel.

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

Gallatin River-Yellowstone River drainage divide area location map

Figure 1: Gallatin River-Yellowstone 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 Gallatin River-Yellowstone River drainage divide in the northern Gallatin Range and illustrates a region of south-central Montana with a strip of northwest Wyoming along the figure 1 south edge. The Crazy Mountains are located slightly west of the figure 1 center. The Yellowstone River flows from the Yellowstone National Park area in northwest Wyoming in a northwest and north-northeast direction to Livingston, Montana. From Livingston the Yellowstone River flows in an east-northeast direction to Big Timber before turning to flow in an east-southeast direction to Greycliff and Columbus. East of figure 1 the Yellowstone River turns to flow in a northeast direction and joins the east oriented Missouri River at the North Dakota border. The Gallatin Range is west of the northwest and north-northeast oriented Yellowstone River south of Livingston, Montana.  West of the Gallatin Range is the north-northwest, north, and northwest oriented Gallatin River, which originates in the Yellowstone National Park northwest corner and which joins the north oriented Madison River and east oriented Jefferson River to form the north oriented Missouri River at Three Forks. The Gallatin River-Yellowstone River drainage divide area in the northern Gallatin Range discussed here is located south of Interstate highway 90 and between the north-northeast oriented Yellowstone River segment (south of Livingston) and the north oriented Gallatin River segment north of Big Sky. Hyalite Peak is located in the high Gallatin Range while Mt. Ellis is located on the Gallatin Range northern flank.

Looking at the big picture erosion history of the figure 1 map area the drainage routes shown developed as immense south and southeast oriented melt water floods flowed across the region and later as the deep Yellowstone River valley and subsequently the deep Missouri River valley eroded headward from a deep “hole” in which a large North American ice sheet was rapidly melting. The deep “hole” was located north and east of the figure 1 map area, which is located along the deep “hole’s” deeply eroded southwest wall. The east and northeast oriented Yellowstone River and the Missouri River valleys eroded headward from the deep “hole” to capture immense south and southeast oriented ice marginal floods flowing from western Canada across Montana. At that time mountain ranges in the figure 1 map area, including the Gallatin Mountains, did not stand high above the surrounding regions and floodwaters could freely flow across the entire figure 1 map area. Over time, however, uplift of mountain ranges channeled the huge south and southeast oriented melt water floods into valleys or basins between the rising mountains. One such flood flow channel was between the Gallatin, and Absaroka mountain ranges along the alignment now used by the northwest and north-northeast oriented Yellowstone River. This flood flow channel was dismembered by continued crustal warping and by headward erosion of the deep northeast and east oriented Yellowstone River from the deep “hole” the melting ice sheet had once occupied. During this dismemberment process, what had been a south-southwest and southeast oriented flood flow channel was reversed to form the northwest and north-northeast oriented Yellowstone River south of Livingston. Ongoing uplift of adjacent mountain ranges and of the Yellowstone Plateau region to the south helped greatly in this flood flow reversal process.  A similar flood flow reversal process occurred west of the Gallatin Range to reverse flow on what had been a south oriented flood flow channel to create the north oriented Gallatin River and the north oriented Missouri River segment further to the north.

For a time as the Gallatin Range was being uplifted the south and southeast oriented floodwaters flowed across them and carved deep valleys into the rising mountain mass, although gradually the south and southeast oriented flood flow was captured by the developing south oriented channel along the Gallatin Range west flank. Evidence of these southeast and south oriented flood flow routes is found in the barbed southeast oriented tributaries flowing to the present day north-northeast oriented Yellowstone River segment and also in the north and northwest oriented Gallatin River tributaries. As is seen in the topographic maps illustrated below the southeast oriented Yellowstone River tributary valleys are linked by through valleys (which in some cases may appear to be simply mountain passes or notches in high mountain ridges) to the north and northwest oriented Gallatin River tributary valleys. The through valleys and the tributary valley orientations were established at a time when the Gallatin Range was just beginning to emerge and the deep Gallatin River valley to the west did not yet exist. South and southeast oriented floodwaters were flowing across the emerging Gallatin Range to the south oriented flood flow channel being carved at that time on the present day north oriented Yellowstone River alignment.

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

Figure 2: Detailed location map for Gallatin River-Yellowstone 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 Gallatin River-Yellowstone River drainage divide area in the northern Gallatin Range. County boundaries are shown and the Gallatin River-Yellowstone River drainage divide area in the northern Gallatin Range is located in Gallatin and Park Counties. Green shaded areas are National Forest lands, which generally are located in mountainous regions. The brown shaded along the figure 2 south edge is Yellowstone National Park land, most of which is south of figure 2. The Yellowstone River flows in a northwest direction from the south center edge of figure 2 to Miner in southwest Park County and then turns to flow in a north-northeast direction to Livingston. From Livingston the Yellowstone River flows in an east-northeast direction to Big Timber (near figure 2 northeast corner) and then turns to flow in a southeast direction. Note how the north-northeast Yellowstone River segment has several southeast oriented tributaries. Trail Creek and Eightmile Creek are labeled. Big Creek is a labeled northeast and east oriented Yellowstone River tributary, which has a south-southeast oriented tributary shown. The Gallatin River flows in a north-northwest and north direction from the Yellowstone National Park northwest corner to near Bozeman Hot Springs and then to the figure 2 north edge. Note how the Gallatin River has northwest-oriented tributaries including the East Gallatin River and its Bear Creek tributary, Hyalite Creek, and Big Bear Creek. As is seen in the topographic maps illustrated below the northwest oriented Gallatin River tributary valleys are often linked by through valleys (mountain passes or notches in high mountain ridges) with southeast oriented Yellowstone River tributary valleys. Orientations of these Gallatin River and Yellowstone River tributaries and the linkages of the valleys across the present day drainage divide provide evidence of former southeast oriented flood flow routes, which were beheaded and reversed as crustal warping raised the Gallatin Range and as headward erosion of a south oriented valley on the present day north oriented Gallatin River alignment captured the flood flow. Ongoing Yellowstone Plateau area uplift combined with headward erosion of the deep northeast and east oriented Missouri River valley (north of figure 2) caused a major flood flow reversal that resulted in the present day north-oriented Gallatin River. Topographic maps show below begin with Bozeman Pass on the highway between Bozeman and Livingston and then follow the Gallatin River-Yellowstone River drainage divide south to Big Creek.

Jackson Creek-Billman Creek drainage divide area at Bozeman Pass

Figure 3: Jackson Creek-Billman Creek drainage divide area at Bozeman Pass. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 3 provides a topographic map of the Jackson Creek-Billman Creek drainage divide area at Bozeman Pass. Bozeman Pass is labeled, is located near the figure 3 center, and is used by both the highway and the railroad to cross the Gallatin River-Yellowstone River drainage divide. Billman Creek is the east oriented stream flowing from Bozeman Pass to the east center edge of figure 3. Jackson Creek is the southwest oriented stream west of Bozeman Pass and is joined by northwest oriented Timberline Creek and then near Chestnut by northwest oriented Meadow Creek to become west and northwest oriented Rock Creek, which joins the north-northwest and northwest oriented East Gallatin River near Mount Ellis. Note how there is a northwest to southeast oriented through valley extending from Bridger Creek near the north edge of figure 3 (west of center) to Bozeman Pass, with the northwest end of the through valley drained by northwest oriented Spring Creek, which flows to Bridger Creek. Bridger Creek flows in a south direction along the west side of the Bridger Range to the figure 3 map area and then in the northwest quadrant of figure 3 turns to flow in a west direction between the Bridger and Gallatin Ranges to join the northwest oriented East Gallatin River. The northwest to southeast oriented through valley linking the south oriented Bridger Creek valley (north of figure 3) with Bozeman Pass and Billman Creek is evidence of a former flood flow channel, which once supplied flood waters to the Yellowstone River valley and which was responsible for eroding the Bozeman Pass through valley. Crustal warping that raised the Bridger and Gallatin Ranges combined with headward erosion of the deep Gallatin River valley (first as a south oriented flood flow channel and later as a reversed north oriented flood flow channel and river) resulted in flood flow captures that diverted all of the south oriented Bridger Creek valley flood flow to the newly reversed north oriented Gallatin River and Missouri River.

Detailed map of Jackson Creek-Billman Creek drainage divide at Bozeman Pass

Figure 4: Detailed map of Jackson Creek-Billman Creek drainage divide area at Bozeman Pass. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 4 provides a detailed topographic map of the Jackson Creek-Billman Creek drainage divide area at Bozeman Pass, which was seen in less detail in figure 3. Bozeman Pass is located near the figure 4 center. Billman Creek is the east oriented stream flowing from Bozeman Pass to the east edge of figure 4 and east of figure 4 flows to the Yellowstone River. Jackson Creek flows in a southwest direction from the north center edge of figure 4 to near the southwest corner of figure 4. Timberline Creek is the northwest and north oriented tributary joining Jackson Creek near the east edge of section 15. The map contour interval is 40 feet and the Bozeman Pass elevation at the drainage divide is given as 5718 feet. Note in section 12, just north of Bozeman Pass, a northwest to southeast oriented through valley linking the Jackson Creek valley with the Billman Creek valley. This through valley has an elevation at the drainage divide of between 5720 and 5760 feet and is a pass almost as deep as Bozeman Pass. Based on elevations seen in figure 4 these two passes are at least 600 feet deep and much higher elevations can be seen both north and south of figure 4. The dual through valleys converging at Bozeman Pass provide evidence of diverging and converging anastomosing flood flow channels that once crossed the region. Flood flow was moving in a southeast and east direction probably to the south oriented flood flow channel on the present day north oriented Yellowstone River alignment. Headward erosion of the much deeper east and northeast oriented Yellowstone River valley subsequently captured the flood flow (east of figure 4). At some point headward erosion of the south-oriented flood flow channel on the present day north oriented Gallatin River alignment captured the flood flow and diverted the floodwaters to the southwest. Headward erosion of the deep northeast and east oriented Missouri River valley (combined with Yellowstone Plateau and Gallatin Range uplift) beheaded and reversed flood flow on the Gallatin River alignment to produce the present day north oriented Gallatin River, which captured the southwest oriented flood flow (resulting in the present day southwest oriented Jackson Creek-northwest oriented Rock Creek and East Gallatin River flow route).

Meadow Creek-Trail Creek drainage divide area

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

Figure 5 illustrates the Meadow Creek-Trail Creek drainage divide area south of figure 3 and includes overlap areas with figure 3. Bozeman Pass is located near the north center edge of figure 5. Jackson Creek flows in a south and southwest direction from the north edge of figure 5 (west of Bozeman Pass) to near Chestnut where it joins northwest oriented Meadow Creek to form west-southwest and northwest oriented Rock Creek, which in turn joins the north-northwest and northwest oriented East Gallatin River near Mount Ellis (near northeast corner of figure 5). Note how Meadow Creek flows in a northwest direction on the northwest end of a northwest to southeast oriented through valley. The southeast end of the through valley (as seen in figure 5) is drained by Trail Creek, which flows in a north-northeast direction to Hoffman (site) before turning to flow in a southeast direction on the southeast end of the through valley. The figure 5 contour interval is 50 meters and the through valley elevation at the Meadow Creek-Trail Creek drainage divide is between 1800 and 1850 meters.  Elevations on either side of the through valley rise to more than 2200 meters suggesting the through valley is approximately 400 meters deep. The through valley is a water-eroded feature and was eroded by southeast oriented flood flow moving to what was probably a south oriented flood flow channel on what is today the north oriented Yellowstone River alignment. Gallatin Range uplift combined with headward erosion of a south oriented flood flow channel on what is today the north oriented Gallatin River alignment probably beheaded the southeast oriented flood flow to the Yellowstone River flood flow channel and floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to form northwest oriented Meadow Creek. Headward erosion of deep east and northeast oriented Yellowstone River valley, combined with Yellowstone Plateau area uplift, next beheaded and reversed the south oriented flood flow on the Yellowstone River alignment to produce the present day north oriented Yellowstone River. Subsequently Yellowstone Plateau uplift combined with headward erosion of the deep northeast and east oriented Missouri River valley beheaded and reversed south oriented flood flow on the Gallatin River alignment to create the north oriented Gallatin River.

Trail Creek-Yellowstone River drainage divide area

Figure 6: Trail Creek-Yellowstone River 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 Trail Creek-Yellowstone River drainage divide area southeast of the figure 5 map area and includes overlap areas with figure 5. Hoffman (site) is located near the northwest corner of figure 6 and Trail Creek flows in a north-northeast direction to Hoffman where it enters the northwest to southeast oriented through valley and turns to flow in a southeast and south direction to enter the Yellowstone River valley. Once in the Yellowstone River valley Trail Creek makes a U-turn to flow in a north-northeast direction to eventually join the north-northeast oriented Yellowstone River. Note the northwest to southeast oriented through valley between The Hogback and Antelope Butte, which is a continuation of the Meadow Creek-Trail Creek through valley further to the northwest. Also note the other southeast oriented streams flowing to the north-northeast oriented Yellowstone River. These southeast oriented barbed tributaries provide evidence the Yellowstone River valley alignment was first established as a south oriented flood flow channel. The through valley between The Hogback and Antelope Butte provides evidence of what were once diverging flood flow channels moving floodwaters to the south oriented Yellowstone River flood flow channel. Further, note northwest oriented tributaries flowing to the Yellowstone River in the southeast corner of figure 6. These northwest oriented tributary orientations may have been established as reversals of flood flow on northwest ends of southeast oriented flood flow routes when the deep south oriented Yellowstone River flood flow channel eroded headward into the region. Subsequently  Yellowstone Plateau uplift south of figure 6 combined with headward erosion of the deep east and northeast oriented Yellowstone River valley north of figure 6 beheaded and reversed flood flow on the Yellowstone River alignment to produce the present day north oriented Yellowstone River.

Bear Creek-Trail Creek drainage divide area

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

Figure 7 illustrates the Bear Creek-Trail Creek drainage divide area south and slightly west of the figure 5 map area and includes a significant overlap area with figure 5. Northwest oriented Meadow Creek joins Jackson Creek near the north center edge of figure 7 to form west-southwest and northwest oriented Rock Creek, which can be seen along the north edge of figure 7. Note how northwest to southeast oriented Chestnut Mountain is located in the north center area of figure 7. Bear Creek originates just south of the center of figure 7 and flows in a northwest and north-northwest direction to join Rock Creek just north of the north edge of figure 7. South of Bear Creek is the high Gallatin Range ridge and Bear Creek flows in a northwest oriented valley between the Gallatin Range and Chestnut Mountain. That northwest oriented valley also extends in a southeast direction beyond the Bear Creek headwaters to the north-northeast Trail Creek valley. The contour interval in figure 7 is 50 meters. Chestnut Mountain rises to more than 2300 meters while the Gallatin Range is even higher. The Bear Creek-Trail Creek through valley at its lowest point has an elevation of between 1950 and 200 meters, which means it is at least 300 meters deep. This 300-meter deep through valley linking the northwest oriented Bear Creek valley with the north-northeast and southeast oriented Trail Creek valley provides evidence of converging southeast oriented flood flow routes in what was once a southeast oriented anastomosing channel complex being eroded into what was probably a rising mountain region. Floodwaters were moving to a deep south oriented flood flow channel on the present day Yellowstone River alignment. Uplift of the Gallatin Range and adjacent mountains combined with headward erosion of a south oriented flood flow channel on the present day north oriented Gallatin River alignment beheaded and reversed southeast oriented flood flow on the Bear Creek alignment (and later on the Meadow Creek alignment). Subsequently Yellowstone Plateau area uplift south of figure 7 combined with headward erosion of the deep Yellowstone and Missouri River valleys north of figure 7 reversed flood flow in the south oriented Yellowstone and Gallatin River flood flow channels to produce the north oriented Yellowstone and Gallatin Rivers seen today. The northwest stream flowing across the southwest corner of figure 7 is Hyalite Creek, which is seen in figure 8.

Hyalite Creek-Eightmile Creek drainage divide area

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

Figure 8 illustrates the Hyalite Creek-Eightmile Creek drainage divide area south of figure 7 and includes a small overlap area with figure 7. Hyalite Creek flows in a north direction from the south edge of figure 8 (west half) to Crescent Lake and then in a northwest direction to the north edge of figure 8 (near northeast corner). North and west of figure 8 Hyalite Creek joins the north and northwest oriented Gallatin River. At Crescent Lake Hyalite Creek is joined by its north-northeast and northwest oriented East Fork, which originates at Heather Lake (just north of Mount Chisholm). Eightmile Creek flows from the center region of figure 8 in an east-southeast direction to the Yellowstone River valley (seen in the southeast corner of figure 8). The South Fork of Eightmile Creek flows in a north direction before turning to flow in an east direction to join the south-oriented North Fork and to form east-southeast oriented Eightmile Creek. While not as obvious as the through valleys seen in the previous figures the northwest oriented Hyalite Creek valley is linked by a through valley with the east-southeast oriented Eightmile Creek. The through valley is the deep notch in the otherwise high mountain ridge separating the East Fork Hyalite Creek valley from the South Fork Eightmile Creek valley. The map contour interval is 50 meters. Elevations on the through valley floor (or the notch floor) at the drainage divide are between 2700 and 2750 meters. North of the through valley (or notch) elevations rise to more than 2900 meters while to the south elevations rise to more than 3000 meters. The through valley (or notch) is evidence of a former southeast oriented flood flow channel, which was carved at least 150 meters deep into the rising mountain mass. Today the floor of the through valley (or notch) is almost 500 meters higher than floors of the adjacent valleys, which provides a measure of the uplift that occurred following the beheading and reversal of southeast and south oriented flood flow to the former south oriented flood flow channel on the present day north oriented Yellowstone River alignment.

Detailed map of Hyalite Creek-Eightmile Creek drainage divide area

Figure 9: Detailed map of Hyalite Creek-Eightmile Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 9 provides a detailed topographic map of the East Fork Hyalite Creek-South Fork Eightmile Creek drainage divide area seen in less detail in figure 8 above. The East Fork Hyalite Creek flows in a north direction from section 6 (straddling south edge of figure 9) in a north direction to the southwest corner of section 30 where it turns to flow in a northwest direction to the northwest corner of figure 9. Flanders Creek is the north oriented tributary west of the north oriented East Fork segment. The South Fork Eightmile Creek flows in a north direction from section 1 (the dark shaded section straddling the south edge of figure 1 just east of center) and then turns to flow in an east direction to the east center edge of figure 1. The through valley (or notch in a high mountain ridge) linking the northwest oriented East Fork Hyalite Creek valley with the east oriented Eightmile Creek valley is located near the east margin of section 31. The contour interval for the figure 9 map is 40 feet and the floor of the through valley (or notch) is between 8840 and 8880 feet. The mountain peak near the north center edge of figure 1 rises to more than 9600 feet. The spot elevation near the south center edge of figure 9 reads 9441 feet, although elevations greater than 9600 feet are found just south of figure 9. In other words the through valley or notch is evidence of a former southeast and east oriented valley, which was at least 700 feet deep. Today the floor of that former valley stands approximately 1600 feet higher than the floors of the deep valleys on either side, which provides a measure of the amount of regional uplift and of deep valley erosion since the southeast and east oriented flood flow channel was dismembered by Gallatin Range uplift and headward erosion of the deep Gallatin River valley to the west.

Hyalite Creek-Yellowstone River drainage divide area

Figure 10: Hyalite Creek-Yellowstone River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software. 

Figure 10 illustrates the Hyalite Creek-Yellowstone River drainage divide area south and slightly west of the figure 8 map area and includes overlap areas with figure 8. The northeast oriented Yellowstone River crosses the southeast corner of figure 10 and Paradise Valley is the name for the Yellowstone River valley in this region. Big Creek is the east-northeast and east oriented tributary joining the Yellowstone River near the southeast corner of figure 10. Note multiple southeast-oriented Big Creek tributaries and Yellowstone River tributaries north and east of Big Creek. These multiple southeast oriented streams flowing to a north oriented river are barbed tributaries and provide evidence of a capture event that resulted in a reversal of a former south oriented drainage route. The southeast oriented tributary orientations are relics from the southeast oriented anastomosing complex of flood flow channels that once crossed the region. Hyalite Creek originates at Hyalite Lake in the north center of figure 10 and flows in a north direction to the north edge of figure 10 and then in a northwest direction to the Gallatin River. West of Hyalite Creek is Hyalite Ridge. The west-northwest stream flowing from Hyalite Ridge to the northwest corner of figure 10 is Squaw Creek, which joins the north oriented Gallatin River, which is located west of figure 10. The Gallatin Range in figure 10 appears to be a high mountain ridge, although a close look reveals notches (or through valleys) linking north, northwest, and west oriented Gallatin River tributary valleys with southeast oriented Big Creek and Yellowstone River tributary valleys. The map contour interval is 50 meters. The notches, or through valleys, are defined by as many as 3 or 4 contour lines. While certainly not the first feature most observers see on figure 10 the notches, or through valleys, are evidence of an anastomosing channel complex that crossed the Gallatin Range at a time when the Gallatin Range was not the high mountain ridge it is today. Flood waters deeply eroded the rising mountain mass as they moved to the developing south oriented Yellowstone River flood flow channel. Subsequently, aided by Gallatin Range uplift, the southeast oriented floodwaters were beheaded and reversed by headward erosion of the south oriented Gallatin River flood flow channel. Still later Yellowstone Plateau uplift and headward erosion of the deep Yellowstone and Missouri River valleys to the north beheaded and reversed the Yellowstone and Gallatin River flood flow channels to produce the north oriented Yellowstone and Gallatin River seen 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.