Yellowstone River-Snake River drainage divide area landform origins along continental divide in Yellowstone National Park, Wyoming, USA

Authors


 

Abstract:

This essay uses topographic map evidence to interpret landform origins in the region between the Yellowstone and Snake Rivers along the continental divide in Yellowstone National Park, which is located in northwest Wyoming and is south of Yellowstone Lake. The Yellowstone River flows in a north direction to the east edge of the Yellowstone Lake Southeast Arm and then in a north direction north of Yellowstone Lake with water eventually reaching the Gulf of Mexico. West of the north oriented Yellowstone River is the northwest and south oriented Snake River with water eventually reaching the Pacific Ocean. West of the Yellowstone River and north of the Snake River short north oriented streams flowing to Yellowstone Lake are linked by through valleys with south and southwest oriented Snake River tributary valleys. Generally the Snake River tributary valleys are significantly deeper than floors of the north oriented stream valleys. The observed through valleys, barbed tributaries, water gaps, and the Snake River abrupt turn are interpreted in the context of diverging and converging flood flow channels that once crossed the region. Floodwaters are interpreted to have been derived from the western margin of a melting thick North American ice sheet and were flowing in south and southeast directions from western Canada to and across the study region. Crustal warping related to the thick ice sheet presence north and east of the study region was responsible for uplift of the Yellowstone Plateau and the regional mountain ranges as floodwaters flowed across the region. The northwest oriented Snake River headwaters valley originated as a southeast oriented flood flow channel that was subsequently beheaded and reversed by headward erosion of the much deeper south oriented Snake River valley. The present day north oriented Yellowstone River valley also originated as a south oriented flood flow channel and was subsequently reversed to create the north oriented drainage route seen today. The Yellowstone River flood flow reversal was probably caused by crustal warping that raised the Yellowstone Plateau area and by headward erosion of the much deeper northeast oriented Yellowstone River valley (in Montana) from space in the deep “hole” the melting ice sheet was opening up. This much deeper Yellowstone River valley beheaded south oriented flood flow channels crossing the Yellowstone Plateau area and floodwaters on north ends of the beheaded flood flow channels reversed flow direction to create the north oriented drainage system in the Yellowstone Plateau region. The size of some of the observed through valleys suggests immense quantities of south oriented floodwaters flowed across the region.

Preface

The following interpretation of detailed topographic map evidence is one of a series of essays describing similar evidence for all major drainage divides contained within the Missouri River drainage basin and for all major drainage divides with adjacent drainage basins. The research project is interpreting evidence in the context of a previously unexplored deep glacial erosion paradigm, which is fundamentally different from most commonly accepted North American glacial history interpretations. Project essays 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 Yellowstone River-Snake River drainage divide area landform origins along the continental divide in Yellowstone National Park, which is located in northwest Wyoming. 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 Yellowstone River-Snake River drainage divide area landform evidence along the continental divide located in Yellowstone National Park, Wyoming will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

Yellowstone River-Snake River drainage divide area location map

Figure 1: Yellowstone River-Snake 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 Yellowstone River-Snake River drainage divide area along the continental divide located in Yellowstone National Park and illustrates a region of northwest Wyoming with Yellowstone National Park located in the northwest corner of Wyoming. The Yellowstone River originates south of the Yellowstone National Park southeast corner and flows in a north-northwest direction to Yellowstone Lake. From Yellowstone Lake the Yellowstone River flows in a northwest direction to Canyon and then in a northeast, north, and northwest direction to the north edge of figure 1 (west half). North of figure 1 to Yellowstone River turns to flow in more of a north and northeast direction before turning to flow in roughly an east and then northeast direction to join the Missouri River at the Montana-North Dakota border with water eventually reaching the Gulf of Mexico. East of Yellowstone National Park Clarks Fork Yellowstone River flows in a southeast and then northeast direction to the north edge of figure 1 (east half) and then joins the Yellowstone River. Further south the northeast oriented Shoshone River and Greybull River flow to the east edge of figure 1 and east of figure 1 join the north oriented Bighorn River, which flows to the northeast oriented Yellowstone River. South of Yellowstone Lake and slightly west of the north oriented Yellowstone River are northwest oriented headwaters of the Snake River, which south of Heart Lake turns to flow in south, west, and south direction to Jackson Lake in Grand Teton National Park. From Jackson Lake the Snake River continues to flow in south direction before turning to flow in a northwest direction into Idaho where it turns to flow in a southwest and northwest direction and then in a north direction with water eventually reaching the Pacific Ocean. This essay focuses on the Yellowstone River-Snake River drainage divide area east of Lewis Lake, south of Yellowstone Lake, and north of the Yellowstone National Park southern boundary.

Before looking at the detailed maps a brief look at the big picture drainage history will help in understanding interpretations given below. Drainage routes shown in figure 1 developed as immense south and southeast oriented melt water floods flowed across the region and as crustal warping raised the Yellowstone Plateau area. Floodwaters were derived from the west margin of a melting thick North American ice sheet and were flowing from western Canada to and across the region shown in figure 1. As the immense south and southeast oriented floods crossed the region the deep east and northeast oriented Yellowstone River valley eroded headward from space being opened up in a deep “hole” in which the large ice sheet was rapidly melting. The deep “hole” was located north and east of the figure 1 map area. The map area in figure 1 is located along the deep “hole’s” deeply eroded southwest wall. The deep east and northeast oriented Yellowstone River valley (east and north of figure 1) eroded headward from the deep “hole” to capture immense the south and southeast oriented ice marginal floods and beheaded the much shallower south oriented flood flow channels crossing the figure 1 map area. Floodwaters on north ends of beheaded flood flow channels reversed flow direction and with the aid of crustal warping that was raising the Yellowstone Plateau and regional mountain ranges created the north and northwest oriented Yellowstone River drainage route seen today. Prior to the massive flood flow reversal the floodwaters had been flowing to the actively eroding south oriented Snake River valley and tributary valleys. Headward erosion of a deeper south-southwest oriented valley beheaded and reversed the northwest end of a southeast oriented flood flow channel to create the present day northwest oriented Snake River headwaters route. Topographic map evidence is not adequate to determine origins for Yellowstone Lake, Heart Lake, and Lewis Lake and this essay will not attempt to do so.

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

Figure 2: Detailed location map Yellowstone River-Snake 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 Yellowstone River–Snake River drainage divide area in Yellowstone National Park. Yellowstone Lake is located in the south half Yellowstone National Park, which is shown by the red-brown shaded area in the north half of figure 2. The east-west continental divide is shown with a labeled dashed line and extends from the northwest corner of figure 2 in a southeast and northeast direction around the Old Faithful region and then in a southeast direction south of Yellowstone Lake to the southeast corner region of figure 2. Drainage north of the continental divide flows to the Gulf of Mexico while drainage south of the continental divide flows to the Pacific Ocean. The study region in this essay extends from the West Thumb area on the west shore of Yellowstone Lake to the south edge of Yellowstone National Park near where the north oriented Yellowstone River enters the Park. The Yellowstone River originates in the Thorofare Plateau area located in the southeast quadrant of figure 2 and flows in a northwest and north-northwest direction to the southeast corner region of Yellowstone National Park and then to Yellowstone Lake. North of figure 2 the Yellowstone River flows in a northwest, northeast, and northwest direction into Montana where it turns to flow in more of a northeast, east, and northeast direction. Chipmunk Creek is a labeled northwest and north oriented stream west of the north-northwest Yellowstone River flowing to Yellowstone Lake. Other study region Yellowstone River and Yellowstone Lake tributaries are not labeled and are relatively short. The Snake River originates near the Yellowstone National Park south border and south of the Two Ocean Plateau (which is located between Chipmunk Creek and the Yellowstone River) and flows in a northwest direction to a point south of Heart Lake where it turns to flow in a south, northeast, southwest, and south direction to Jackson Lake in Grand Teton National Park. South of figure 2 the Snake River continues to flow in a south direction before turning to flow in a northwest direction into Idaho. Study region Snake River tributaries are also short and unlabeled in figure 2. As will be seen in the topographic maps illustrated below through valleys link the north oriented and east oriented Yellowstone Lake and Yellowstone River tributary valleys with the south and southwest oriented Snake River tributary valleys. The through valleys were eroded as south oriented flood flow channels moving immense quantities of floodwaters to the actively eroding Snake River drainage basin. Flood flow across the present day continental divide ended when uplift of the Yellowstone Plateau area combined with headward erosion of the much deeper northeast oriented Yellowstone River valley across Montana to the north caused a massive flood flow reversal that created the present day north oriented Yellowstone River drainage system and diverted the floodwaters to space in the deep “hole” the melting ice sheet was opening up. This massive flood flow reversal took place in stages even if  in my descriptions below may give the impression it occurred all at once. My goal in this essay is to illustrate in a general way what happened and to try to provide all of the details will require a much more detailed discussions than I am providing here.

Yellowstone Lake-Heart Lake drainage divide area

Figure 3: Yellowstone Lake-Heart Lake drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 3 provides a topographic map of the Yellowstone Lake-Heart Lake drainage divide area in southern Yellowstone National Park. The “South Arm” seen in the east half of figure 3 is the South Arm of Yellowstone Lake. Grant Village near the northwest corner of figure 3 is on the south shore of West Thumb (of Yellowstone Lake). Heart Lake straddles the south edge of the southwest quadrant of figure 3 and the Red Mountains are west of Heart Lake. The east-west continental divide is shown with a labeled dashed line and extends in an east direction from the west edge of figure 3 (north half) to Flat Mountain and then in a south direction to Channel Mountain and the south edge of figure 3 (east of center). South and west of the continental divide drainage flows to the Snake River with water eventually reaching the Pacific Ocean. Water north and east of the continental divide flows to the Yellowstone River and eventually reaches the Gulf of Mexico. Solution Creek is an east and north oriented stream in the northwest quadrant of figure 3 and flows from Riddle Lake to the West Thumb (Yellowstone Lake). South of Riddle Lake are headwaters of southeast oriented Witch Creek, which flows to Heart Lake. South of figure 3 Heart Lake is drained by the Heart River, which flows to the Snake River. South of figure 3 the Snake River and Snake River tributaries make some interesting jogs, which are linked by north-to-south oriented through valleys, but in figure 3 note how the north oriented Solution Creek valley is linked by a north-to-south oriented through valley with the southeast oriented Witch Creek valley. The map contour interval for figure 3 is 50 meters and the through valley floor elevation at the drainage divide is between 2450 and 2500 meters. The Yellowstone Lake elevation is 2357 meters and the Heart Lake elevation is 2271 meters. Elevations in the Red Mountains west of Heart Lake rise to 3142 meters and the Flat Mountain elevation rises to 2805 meters suggesting the north-to-south oriented through valley is approximately 300 meters deep. South of Flat Mountain is south and south-southwest oriented Surprise Creek, which is linked by a through valley with an unnamed northeast oriented South Arm (Yellowstone Lake) tributary. The floor elevation of this second through valley is also between 2450 and 2500 meters. Just south of Channel Mountain and the south edge of figure 3 is Overlook Mountain, which rises to more than 2800 meters. Based on the Overlook and Flat Mountain elevations this second through valley is approximately 300 meters deep. These through valleys were eroded by south oriented flood flow moving to what was then the actively eroding south oriented Snake River drainage basin.

Detailed map of Solution Creek-Witch Creek drainage divide area

Figure 4: Detailed topographic map of the Solution Creek-Witch 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 Solution Creek-Witch Creek drainage divide area seen in less detail in figure 3 above. Riddle Lake is located near the northwest corner of figure 4. Solution Creek meanders in an east direction from Riddle Lake and then turns to flow in a north direction to north edge of figure 4 (west half) and north of figure 4 flows to Yellowstone Lake and to the north oriented Yellowstone River with water eventually reaching the Gulf of Mexico. The Red Mountains straddle the south edge of the southwest quadrant of figure 4. Witch Creek flows in an east direction north of the Red Mountains and then turns to flow in a southeast direction to the south edge of figure 4 (west half) and south of figure 4 flows to Heart Lake and the Heart River, which flows to the Snake River with water eventually reaching the Pacific Ocean. The east-west continental divide is shown with a labeled dashed line and extends from the west edge of figure 4 (north half) to the east edge of figure 4 (north half). Beaver Creek is a south and south-southeast oriented stream originating near the continental divide (in northeast quadrant of figure 4) and flows to the south edge of figure 4 (east half) and south of figure 4 flows to Heart Lake. The map contour interval for figure 4 is 20 feet. Note the unlabeled south oriented stream originating near the center of figure 4 and flowing to the south center edge of figure 4. South of figure 4 this stream joins Witch Creek. Note how a through valley links the north oriented Solution Creek valley with this south oriented Witch Creek tributary valley. The elevation at the drainage divide is between 8000 and 8020 feet. The Red Mountains rise to 10,305 feet, although the highest elevations are south of figure 4. Flat Mountain is just east of the northeast corner of figure 4 and rises to 9168 feet. These elevations suggest the north-to-south oriented through valley linking the north oriented Solution Creek valley with the southeast oriented Witch Creek valley is as much as 1150 feet deep. The through valley is a water-eroded feature and was eroded by south oriented flood flow moving to the south oriented Snake River drainage basin. South oriented flood flow across the region ended when a massive flood flow reversal created the present day north oriented Yellowstone River drainage basin.

South Arm Yellowstone Lake-Heart River drainage divide area

Figure 5: South Arm Yellowstone Lake-Heart River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 5 illustrates the South Arm Yellowstone Lake-Heart River drainage divide area east of figure 3 and includes a significant overlap area with figure 3. The east-west continental divide is shown by a labeled dashed line and extends from the west edge of figure 5 (north half) to Flat Mountain and then in more of a south direction to Channel Mountain, Overlook Mountain, and the south edge of figure 5 (west of center). The South Arm and Southeast Arm are arms of Yellowstone Lake. The Promontory is large peninsula extending northward between the two arms. Grouse Creek is a north and northeast oriented stream flowing from the south center edge of figure 5 to the South Arm. Chipmunk Creek is a northwest, north, and northwest oriented stream in the southeast quadrant of figure 5 and also flows to the South Arm. The north-northwest oriented Yellowstone River flows into the Southeast Arm near the east center edge of figure 5 (but is not seen in figure 5). North of figure 5 Yellowstone Lake drains to the north oriented Yellowstone River. Heart Lake is located in the southwest quadrant of figure 5 and drains to the south oriented Heart River, which flows to south edge of figure 5 (south of Heart Lake) and then to the Snake River. Surprise Creek flows in a south and south-southwest direction to join the Heart River near the Heart Lake southeast end. Outlet Creek is a southwest and west oriented stream originating at Outlet Lake and flows to the south oriented Heart River near the southeast end of Heart Lake. The South Arm-Surprise Creek through valley has already been described. Further south between Channel Mountain and Overlook Mountain an east-to-west oriented through valley crosses the continental divide and links the northeast oriented Grouse Creek valley with the southwest oriented Outlet Creek valley. The map contour interval for figure 5 is 50 meters and the through valley floor elevation at the continental divide is between 2400 and 2450 meters. Channel Mountain to the north rises to 2665 meters and Overlook Mountain to the south rises to more than 2800 meters suggesting the through valley is at least 200 meters deep. The through valley is a water-eroded feature and was eroded by southwest oriented flood flow moving from the South Arm location to the south oriented Heart and Snake Rivers. These multiple flood flow channels being illustrated here are evidence of diverging and converging flood flow channels in what was a very large-scale anastomosing channel complex. The Yellowstone Lake South and Southeast Arms probably originated as large south oriented flood flow channels and the northwest and north oriented Chipmunk Creek valley (the north of which is seen in figure 5) and the north-northwest oriented Yellowstone River east of figure 5 were created when south oriented flood flow across the region was reversed to create the north oriented Yellowstone River drainage basin. Crustal warping probably caused the flood flow reversal seen here, although headward erosion of the much deeper northeast oriented Yellowstone River valley in Montana to the north of figure 5 may have played a role.

Detailed map of Grouse Creek-Outlet Creek drainage divide area

Figure 6: Detailed map of Grouse Creek-Outlet Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 6 illustrates a detailed topographic map of the Grouse Creek-Outlet Creek drainage divide area seen in less detail in figure 5. The Yellowstone Lake South Arm can be seen in the northeast corner of figure 6. Grouse Creek flows in a north and northeast direction from the south edge of figure 6 (east half) to the east center edge of figure 6 and enters the South Arm east of figure 6. Surprise Creek flows in a south-southwest direction from the north edge of figure 6 (west of center) to the southwest corner of figure 6 and joins the south oriented Heart River south and west of figure 6. Outlet Creek originates at Outlet Lake and flows in a southwest direction to the south edge of figure 6 (west half) and south and west of figure 6 flows to the Heart River. The east-west continental divide is shown with a labeled dashed line and extends from the north edge of figure 6 (east half) along Chicken Ridge to Channel Mountain and then to the south center edge of figure 6. Directly south of the south center edge of figure 6 is Overlook Mountain, which rises to 9370 feet (the map contour interval for figure 6 is 20 feet). Note the well-defined east-to-west oriented through valley linking the northeast oriented Grouse Creek valley with the southwest oriented Outlet Creek valley. The through valley floor elevation at the continental divide is between 7980 and 8000 feet. Channel Mountain to the north rises to 8745 feet suggesting the through valley is at least 745 feet deep. Note the sharp drop just west of the continental divide. Outlet Lake has an elevation of between 7760 and 7780 feet and is more than 200 feet lower in elevation than the continental divide elevation in the through valley just to the east. The through valley was eroded by southwest oriented flood flow moving from the Yellowstone Lake basin to the south oriented Snake River. Outlet Lake was probably formed as a plunge pool at the base of what was once a 200-foot high water falls that was eroding headward along the southwest oriented flood flow channel. The flood flow reversal that created the north oriented Yellowstone River drainage system occurred before the much deeper south oriented Outlet Creek valley could erode headward into the South Arm area. Had the deeper south oriented Outlet Creek valley head been able to erode headward into the South Arm area Yellowstone Lake would probably today drain to the Snake River rather than to the north oriented Yellowstone River.

Yellowstone Lake-Snake River drainage divide area

Figure 7: Yellowstone Lake-Snake River drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Yellowstone Lake-Snake River drainage divide area south of figure 5 and includes an overlap area with figure 5. The continental divide is shown with a labeled dashed line and extends from the north center edge area of figure 7 to the southeast quadrant of figure 7. Heart Lake is located near the northwest corner of figure 7. The Heart River flows in a southwest direction from the southeast end of Heart Lake to join the northwest and south oriented Snake River, which flows from the south center edge of figure 7 to near the southwest corner of figure 7 with water eventually reaching the Pacific Ocean. Crooked Creek is a west-northwest and south oriented stream joining the northwest oriented Snake River near the south center edge of figure 7. West and north of Crooked Creek Sickle Creek flows in a southwest direction to join the northwest oriented Snake River. Note how Sickle Creek has eroded a deep water gap across the high mountain ridge. The map contour for figure 7 is 50 meters and Barlow Peak to the south rises to 2933 meters while Chicken Ridge to the north rises to more than 3000 meters. The Sickle Creek valley floor between those two high points has an elevation of less than 2450 meters suggesting the water gap is approximately 500 meters deep. Peale Island near the north edge of figure 7 is located at the southern tip of the Yellowstone Lake South Arm. Grouse Creek flows in a north and northeast direction to enter the South Arm with water eventually reaching the Gulf of Mexico. Further east Chipmunk Creek flows in a northwest, north, and west direction to enter the South Arm near the north edge of figure 7. Passage Creek is a northwest and north-northeast oriented Chipmunk Creek tributary. Note how the north oriented Grouse Creek valley is linked by a through valley with the southwest oriented Sickle Creek valley. Similar, but higher elevation through valleys link the north oriented Passage Creek valley with the south oriented Crooked Creek valley. The Grouse Creek-Sickle Creek through valley floor elevation at the continental divide is between 2500 and 2550 meters. Chicken Ridge to the west rises to more than 3000 meters while elevations near the northeast corner of figure 7 rise to 2815 meters and to more than 2900 meters east of figure 7. These elevations suggest the Grouse Creek-Sickle Creek through valley is at least 250 meters deep. The through valley was eroded by south oriented flood flow moving from the Yellowstone Lake South Arm location to a southeast oriented flood flow channel on the present day northwest oriented Snake River alignment. South of figure 7 the northwest oriented Snake River valley is linked by a north-to-south oriented through valley with the southwest oriented Pacific Creek valley with Pacific Creek flowing to the south oriented Snake River in Grand Teton National Park. A reversal of south oriented flood flow created the north and northeast oriented Grouse Creek drainage route. A flood flow reversal also created the present day northwest oriented Snake River drainage route seen in figure 7. These reversals of flood flow were probably indirectly related to crustal warping that was unevenly raising the region, but were more directly related to headward erosion of much deeper valleys, which beheaded and reversed south and southeast oriented flood flow channels. In the case of the Snake River headward erosion of the much deeper south oriented Snake River valley beheaded a southeast oriented flood flow channel supplying floodwaters to the southeast oriented flood flow channel on the present day northwest oriented Snake River alignment. Floodwaters on the northwest end of the beheaded flood flow channel reversed flow direction to create the northwest oriented Snake River drainage route seen today.

Detailed map of Grouse Creek-Sickle Creek drainage divide area

Figure 8: Detailed map of Grouse Creek-Sickle Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 8 illustrates a detailed topographic map of the Grouse Creek-Sickle Creek drainage divide area seen in less detail in figure 7. The east-west continental divide is shown with a labeled dashed line and extends from the north edge of figure 8 (west of center) to the east center edge of figure 8. North and east of the continental divide the region drains to the Yellowstone River with water eventually reaching the Gulf of Mexico. South and west of the continental divide the region drains to the Snake River with water eventually reaching the Pacific Ocean. Chicken Ridge is the high mountain ridge extending in a north-to-south direction across figure 8 (just west of center) with Barlow Peak being a southern extension of the ridge. The Snake River flows in a northwest direction from the south edge of figure 8 (west of center) to the west center edge of figure 8. Crooked Creek flows in a west and south direction across the southeast corner of figure 8 and joins the northwest oriented Snake River as a barbed tributary south of figure 8. Sickle Creek originates on the southwest side of the continental divide in the northeast quadrant of figure 8 and flows in a southwest direction to join the northwest oriented Snake River in the southwest quadrant of figure 8. Note how Sickle Creek has eroded a deep water gap across Chicken Ridge. The map contour interval for figure 8 is 40 feet and the swamp at the northeast end of the Sickle Creek water gap has an elevation of between 8040 and 8080 feet. The elevation where Sickle Creek joins the Snake River is between 7480 and 7520 feet. Barlow Peak reaches an elevation of 9612 feet while the peak labeled “Chicken” to the north reaches 9876 feet. These elevations suggest the water gap is from 1500 to 2000 feet deep. Grouse Creek originates on the Chicken Ridge east slope north and east of the continental divide and flows in an east direction before turning to flow in a north-northeast direction to the north edge of figure 8 (east of center). Note how the north-northeast oriented Grouse Creek valley is linked by a through valley east of Chicken Ridge with a southeast oriented Sickle Creek tributary. The through valley floor at the drainage divide is between 8320 and 8360 feet. Near the northeast corner of figure 8 the continental divide rises to 8644 feet and east of figure 8 elevations along the continental divide exceed 10,000 feet suggesting the through valley is at least 300 feet deep and may be as much as 1500 feet deep. The Grouse Creek valley north of the through valley is at almost the same elevation as the through valley floor elevation while the Sickle Creek valley floor elevation is almost 300 feet lower. The through valley was eroded by south oriented flood flow moving from the Yellowstone Lake region in a south direction on the present day north oriented Grouse Creek alignment to a southeast oriented flood flow channel on the present day northwest oriented Snake River alignment. Flood flow reversals south of the present day continental divide created the northwest oriented Snake River drainage route while flood flow reversals north of the present day continental divide created the north oriented Grouse Creek drainage route.

Chipmunk Creek-Yellowstone River drainage divide area

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

Figure 9 illustrates the Chipmunk Creek-Yellowstone River drainage divide area east of the figure 7 and includes a significant overlap area with figure 7. The Yellowstone National Park south border is located near the south edge of figure 9. The east-west continental divide is shown with a labeled dashed line and extends in a meandering direction from the northwest corner of figure 9 to the south edge of figure 9 (east of center). The Snake River flows in a north and northwest direction across the southwest quadrant of figure 9. South of the south edge of figure 9 the Snake River is linked by a north-to-south oriented through valley with the southwest oriented Pacific Creek valley, which drains to the south oriented Snake River in Grand Teton National Park. Plateau Creek is the southwest oriented stream joining the northwest oriented Snake River near the south edge of figure 9. The Yellowstone River flows in a north direction along the east edge of figure 9 and is located in broad and deep valley. North of figure 9 the Yellowstone River flows to the Yellowstone Lake Southeast Arm. The Two Ocean Plateau forms the upland west of the north oriented Yellowstone River valley and has elevations exceeding 3050 meters (the map contour interval for figure 9 is 50 meters). Tributaries to the north oriented Yellowstone River from the west are generally oriented in east-northeast directions and are generally linked by through valleys with drainage routes west of the high Two Ocean Plateau. Lynx Creek is an east-northeast oriented stream originating in the Two Ocean Plateau and flowing to the north oriented Yellowstone River. Note how the east oriented Lynx Creek valley is linked by a through valley with the southwest oriented Plateau Creek valley. The through valley floor elevation at the continental divide is between 2800 and 2850 meters. Elevations on the Two Ocean Plateau both north and south of the through valley exceed 3050 meters suggesting the through valley is at least 200 meters deep. The through valley was probably eroded by a southwest oriented flood flow channel that diverged from a south oriented flood flow channel on the present day north oriented Yellowstone River alignment. The diverging southwest oriented flood flow channel then converged with a southeast and south oriented flood flow channel on the present day northwest oriented Snake River alignment, which then continued in a south direction to a southwest oriented flood flow channel on the Pacific Creek alignment. Flood flow reversals and captures south of the continental divide resulted in creation of the north and northwest oriented Snake River drainage route while east of the continental divide a major flood flow reversal created the north oriented Yellowstone River drainage route.

Detailed map of Lynx Creek-Plateau Creek drainage divide area

Figure 10: Detailed map of Lynx Creek-Plateau 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 Lynx Creek-Plateau Creek drainage divide area seen in less detail in figure 9. The Yellowstone National Park south boundary can be seen near the south edge of figure 10. The east-west continental divide is shown with a labeled dashed line and zigzags along and across the north edge of figure 10 from near the northwest corner to near the northeast corner and then proceeds in a southwest, south, northeast, and south direction to the south edge of figure 10 (on the upland closest to southeast corner). East of the continental divide Lynx Creek flows in an east and east-northeast direction to the east edge of figure 10 (south of center) and joins the north oriented Yellowstone River east of figure 10. West of the continental divide Plateau Creek originates in the northeast quadrant of figure 10 and flows in a southwest, west, and southwest direction to the southwest corner of figure 10 and south and west of figure 10 joins the northwest oriented Snake River. An east-to-west oriented through valley links the east oriented Lynx Creek valley with the west and southwest oriented Plateau Creek valley. The map contour interval for figure 10 is 40 feet and the through valley floor elevation at the continental divide is between 9240 and 9280 (probably closer to 9280) feet. Continental divide elevations in the northeast corner area of figure 10 rise to 10,045 feet while elevations along the continental divide rise to more than 10,000 near the south edge of figure 10. These elevations suggest the through valley is at least 700 feet deep. The through valley is a water-eroded valley and was eroded by west oriented flood flow moving from what was at that time a south oriented flood flow channel on the present day north oriented Yellowstone River alignment to a southeast oriented flood flow channel on the present day northwest oriented Snake River alignment. The floodwaters south of figure 10 turned to move in a south direction to a southwest oriented flood flow channel on the Pacific Creek alignment which led to a south oriented flood flow channel on the Snake River alignment in Grand Teton National Park (see figures 1 and 2). Reversal of the flood flow direction in the Snake River valley created the present day northwest oriented Snake River drainage route. A reversal of flood flow on the Yellowstone River alignment created the north oriented Yellowstone River drainage route and also reversed the Lynx Creek flow direction to create the east oriented Lynx Creek drainage route. Crustal warping that was occurring as floodwaters flowed across the region contributed significantly  to the flood flow reversals and the drainage route diversions.

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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