North Platte River-Little Snake River drainage divide area landform origins along the continental divide in the Wyoming northern Sierra Madre Mountains, USA

Authors

 

Abstract:

This essay uses topographic map evidence to identify north to south and northwest to southeast oriented through valleys crossing the North Platte River-Little Snake River drainage divide in the Wyoming northern Sierra Madre Mountains. The North Platte River flows in a north-northwest direction from Colorado into Wyoming along the east side of the Sierra Madre Mountains and then flows in a north direction to the northwest end of the Laramie Mountains where it turns to flow in a southeast direction into Nebraska with water eventually reaching the Gulf of Mexico. The Little Snake River originates along the west side of the Sierra Madre Mountains and flows in west direction near the Wyoming-Colorado state line before turning in a southwest direction to join the west oriented Yampa River, which then flows to the south oriented Green River with water eventually reaching the Pacific Ocean. Muddy Creek is a northwest, west, and south oriented Little Snake River tributary and Savery Creek is a southwest and south oriented Little Snake River tributary located south and east of Muddy Creek. Muddy Creek and Savery Creek headwaters valleys are linked by northeast to southwest oriented through valleys crossing the present day east-west continental divide with northeast oriented North Platte River tributary valleys. The through valleys are water-eroded valleys and are interpreted to have been eroded by multiple southwest oriented flood flow channels moving floodwaters from what was at that time a south oriented flood flow channel on the present day north oriented North Platte River alignment to actively eroding Little Snake River tributary valleys. At that time the Sierra Madre Mountains were still emerging and floodwaters could flow across what are today high mountain ridges. Floodwaters are interpreted to have flowed from western Canada where the flood flow was derived from the western margin of a thick North American ice sheet. The Sierra Madre Mountains and other regional mountain ranges emerged as floodwaters deeply eroded surrounding basins and valleys and as ice sheet related crustal warping raised the mountain ranges. Reversal of flood flow on the present day north oriented North Platte River alignment occurred as ice sheet related crustal warping raised the Sierra Madre Mountains and surrounding region and when headward erosion of a deep southeast oriented valley around the northwest end of the Laramie Mountains (north of the study area) beheaded the south oriented flood flow channel. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to create the present day north, east, and southeast oriented North Platte River drainage route and ended all southwest oriented flood flow from the North Platte River alignment to what had been the actively eroding Little Snake River valley system.

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 North Platte River-Little Snake River drainage divide area landform origins in the Wyoming northern Sierra Madre Mountains. 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 North Platte River-Little Snake River drainage divide area landform evidence in the Wyoming northern Sierra Madre Mountains will be regarded as evidence supporting the “thick ice sheet that melted fast” paradigm.

North Platte River-Little Snake River drainage divide area location map

Figure 1: North Platte River-Little 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 North Platte River-Little Snake River drainage divide area in the Wyoming northern Sierra Madre Mountains and illustrates a region in southern Wyoming with Colorado and Utah south of Wyoming (Utah is in the southwest corner of figure 1). The North Platte River originates in Colorado and flows in a north-northwest direction from the south edge of figure 1 (east half) into Wyoming between the Medicine Bow Mountains and the Sierra Madre Mountains to slightly north of Fort Steele, Wyoming. After making a northeast jog the North Platte River then flows in a north and northeast direction to Casper at the northwest end of the Laramie Mountains. From Casper the North Platte River flows in an east and southeast direction to the east edge of figure 1 and east of figure 1 flows into Nebraska with water eventually reaching the Gulf of Mexico. North of the Sierra Madre Mountains and west of the north oriented North Platte River is the Great Divide Basin, which is a large region of internal drainage located along the east-west continental divide. Little Sage Creek is an east oriented North Platte River tributary (shown, but not labeled on figure 1) originating north of the Sierra Madre Mountains and south of Rawlins, Wyoming. West of the Great Divide Basin is the south oriented Green River drainage basin with the Green River flowing through Flaming Gorge National Recreation Area and Dinosaur National Park. South of figure 1 the Green River joins the southwest oriented Colorado River with water eventually reaching the Pacific Ocean. The Yampa River is a west oriented river in Colorado (seen along the south edge of figure 1) flowing from near Steamboat Springs to join the Green River in Dinosaur National Park. The Little Snake River is a Yampa River tributary flowing through Savery and Baggs, Wyoming (on Wyoming-Colorado border) and joining the Yampa River near the east edge of Dinosaur National Park. Muddy Creek is a northwest, west, and south oriented stream originating in the Sierra Madre Mountains and joining the Little Snake River near Baggs, Wyoming. Savery Creek (shown, but not labeled on figure 1) originates in the Sierra Madre Mountains and flows in a west and south direction to join the Little Snake River near Savery, Wyoming.  The North Platte River-Little Snake River drainage divide area along the continental divide in the Wyoming Sierra Madre Mountains is located south of Little Sage Creek, west of the North Platte River, and north of Bridger Peak, and includes headwaters areas of Muddy Creek and Savery Creek.

Present day Wyoming, Colorado, and Utah drainage routes developed during immense melt water floods from the western margin of a thick North American ice sheet, which were flowing from western Canada to and across Wyoming. At first, mountain ranges had not emerged and floodwaters could flow across what are today major mountain barriers. Mountain ranges emerged as floodwaters deeply eroded surrounding basins and valleys and as ice sheet crustal warping raised the mountain ranges and much of Wyoming, Colorado, and Utah. The present day north oriented North Platte River drainage route west of the Laramie Mountains originates as a south oriented flood flow channel (actually multiple south oriented flood flow channels, although for purposes of brevity this essay treats the multiple flood flow channels as a single flood flow channel). Headward erosion of a much deeper southeast oriented flood flow channel around the northwest end of the emerging Laramie Mountains beheaded the south oriented flood flow channel west of the Laramie Mountains. Floodwaters on the north end of the beheaded flood flow channel reversed flow direction to flow to the much deeper east and southeast oriented valley north of the Laramie Mountains and to create the north, east, and southeast oriented North Platte River drainage route. Prior to the North Platte River flood flow reversal diverging flood flow channels moved floodwaters from the south oriented flood flow channel on the present day north oriented North Platte River alignment in southwest directions across the emerging Sierra Madre Mountains to what were at that time actively eroding Little Snake River tributary valleys. Emergence of the Sierra Madre Mountains and the reversal of flood flow on the North Platte River alignment ended all southwest oriented flood flow across the Sierra Madre Mountains and created the North Platte River-Little Snake River drainage divide, which is today the east-west continental divide.

Detailed location map for North Platte River-Little Snake River drainage divide area

Figure 2: Detailed location map North Platte River-Little 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 North Platte River-Little Snake River drainage divide area in the Wyoming northern Sierra Madre Mountains. The green colored areas are National Forest lands, which in this region are usually located in mountain areas. The large green colored area in the south half of figure 2 shows National Forest in the Sierra Madre Mountains. The south rim of the Great Divide Basin is shown with a dashed line extending in an east direction from the west edge of figure 2 (near northwest corner) to Bridger Pass and then in a north direction from Bridger Pass to Separation Peak and then to the north edge of figure 2 (west half). North and west of that dashed line all drainage routes end in the Great Divide Basin. The east-west continental divide is shown with the labeled dashed line extending in a southeast direction from Bridger Pass to the south edge of figure 2 (east half). The continental divide segment investigated in this essay extends in a southeast direction from Bridger Pass to just south of Divide Peak in the green colored area. The North Platte River flows in a north-northwest direction from the east edge of figure 2 (south half-on north side of Beaver Creek Hills) to Saratoga and then in a north direction to the north edge of figure 2 (east half). North of figure 2 the North Platte River flows in a north direction to the northwest end of the Laramie Mountains and then flows around the Laramie Mountains in an east and southeast direction with water eventually reaching the Gulf of Mexico. Little Sage Creek is an east oriented North Platte River originating near Separation Creek and flowing near the north edge of figure 2. Sage Creek is a northeast oriented North Platte River tributary originating near the continental divide and is joined by Little Sage Creek just before they join the North Platte River. Jack Creek is a north and northeast oriented tributary joining the North Platte River north of Saratoga. The Little Snake River can be seen flowing in a west direction near the south edge of the southwest quadrant of figure 2 from the town of Savery to the town of Baggs and then turning in a southwest direction. South and west of figure 2 the Little Snake River joins the west oriented Yampa River, which then joins the south oriented Green River with water eventually reaching the Colorado River and Pacific Ocean. Savery Creek is a southwest and south oriented tributary joining the Little Snake River near the town of Savery. Savery Creek is formed at the confluence of its North Fork and East Fork, both of which originate near the continental divide and near Divide Peak, which is located near the north end of the green colored Sierra Madre National Forest area. Little Savery Creek is a south oriented Savery Creek tributary originating near the continental divide located west of the North Fork Savery Creek. Muddy Creek originates near the Little Savery Creek headwaters and flows in a northwest direction to the town of Sulphur and then in west direction before turning to flow in a south direction to join the Little Snake River near Baggs. McKinney Creek is a west and south oriented Muddy Creek tributary located south of Bridger Pass and west of the town of Sulphur.

Little Sage Creek-Muddy Creek drainage divide area

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

Figure 3 provides a topographic map of Little Sage Creek-Muddy Creek drainage divide area. The map contour interval for figure 3 is 20 meters. Miller Hill near the center of figure 3 is the north end of the Sierra Madre Mountains. The east-west continental divide is located on the crest of the north-facing Miller Hill escarpment and can be followed in a northwest direction to Bridger Pass (west of Miller Hill). From Bridger Pass the continental divide turns in a southwest and northwest direction to follow the south rim of Jep Canyon. Jep Canyon is drained by south, southwest, and north oriented Separation Creek, which is located in the Great Divide Basin and which is not linked today to any external drainage routes (although it is linked by through valleys with the North Platte River). Muddy Creek flows in a northwest direction across the southwest corner of figure 3 and west of figure 3 Muddy Creek flows to the Little Snake River with water eventually reaching the Pacific Ocean. Southwest oriented streams originating on Miller Hill flow to northwest and south oriented McKinney Creek, which joins Muddy Creek near the southwest corner of figure 3. North of Miller Hill are northeast oriented Little Sage Creek tributaries with Little Sage Creek being an east oriented North Platte River tributary north of figure 3 (with water eventually reaching the Gulf of Mexico). Emigrant Creek is the northeast oriented Little Sage Creek tributary originating north of Bridger Pass. The northeast to southwest oriented ridge west of Bridger Pass is known as Atlantic Rim. Bridger Pass is located in a large northeast to southwest oriented through valley between Atlantic Rim and Miller Hill. Today the through valley northeast end is drained by northeast oriented Emigrant Creek and the southwest end is drained by south oriented McKinney Creek. The Bridger Pass elevation is shown as being 2286 meters. Miller Hill elevations exceed 2560 meters and high points on Atlantic Rim exceed 2540 meters. These elevations suggest the Bridger Pass through valley is as much as 250 meters deep. The through valley appears to follow the orientation of the regional geologic structures although the through valley is also a water-eroded valley and was eroded by southwest oriented flood flow moving to the Muddy Creek valley. Southwest oriented McKinney Creek tributaries originating along the crest of the north-facing Miller Hill escarpment suggest at one time the through valley did not exist and floodwaters originally flowed on an erosion surface at least as high as the highest points on Miller Hill and the Atlantic Rim crest. Southwest oriented flood flow to the Muddy Creek valley ended when headward erosion of the east oriented Little Sage Creek valley north of figure 3 beheaded all flood flow routes. Floodwaters on the northeast end of the beheaded flood flow routes reversed flow direction to create northeast oriented Little Sage Creek tributary drainage routes (including the Emigrant Creek drainage route).

Detailed map of Emigrant Creek-McKinney Creek drainage divide area

Figure 4: Detailed map of Emigrant Creek-McKinney 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 Emigrant Creek-McKinney Creek drainage divide area seen in less detail in figure 3. The map contour interval for figure 4 is 20 feet. Miller Hill is located in the southeast corner of figure 4 and forms the north end of the Sierra Madre Mountains. Atlantic Rim is the ridge extending in a northeast direction from the west edge of figure 4 (south of center) to the north edge of figure 4 (west of center). Bridger Pass is located in the northeast quadrant of section 8 and represents a low point on the floor of a much broader northeast to southwest oriented through valley. The through valley northeast end is drained by east and northeast oriented Emigrant Creek, which is seen in the north center area of figure 4. North and east of figure 4 Emigrant Creek flows to east oriented Little Sage Creek, which then flows to the North Platte River with water eventually reaching the Gulf of Mexico. The southwest end of the through valley is drained by south oriented tributaries to south oriented McKinney Creek, which flows to northwest, west, and south oriented Muddy Creek with water eventually reaching the Pacific Ocean. The Bridger Pass elevation as shown in figure 4 is 7532 feet. Miller Hill elevations just east of figure 4 exceed 8400 feet. Atlantic Rim elevations in section 7 (west of Bridger Pass) exceed 8340 feet. These elevations suggest Bridger Pass is at least 800 feet deep. The 800-foot deep northeast to southwest oriented through valley is a water-eroded valley and was eroded by southwest oriented flood flow moving from the present day north oriented North Platte River alignment to the Muddy Creek valley. At first the northwest oriented Muddy Creek alignment (seen in figures 2 and 3) was probably the route of a southeast oriented flood flow channel supplying floodwaters to the south oriented Little Savery Creek valley. However, headward erosion of the deeper south and west oriented Muddy Creek valley beheaded and reversed that flood flow channel to create the northwest oriented Muddy Creek headwaters drainage route. Subsequently southwest oriented flood flow to the Muddy Creek valley was beheaded with floodwaters on the northeast end of the beheaded flood flow route reversing flow direction to create the northeast oriented Emigrant Creek drainage route. The beheading of flood flow to the Muddy Creek valley may have been caused by the reversal of flood flow on the North Platte River alignment, although it may have  occurred as ice sheet related crustal warping was raising the Sierra Madre Mountains and the present day Bridger Pass area.

Sage Creek-McCarty Creek drainage divide area

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

Figure 5 illustrates the Sage Creek-McCarty Creek drainage divide area south and east of figure 3 and there is an overlap area with figure 3. The map contour interval for figure 5 is 20 meters. The east-west continental divide is shown with a dashed line extending in a south direction from the north edge of figure 5 (west half-along crest of northeast-facing escarpment) to the crest of the east-facing Sage Creek basin and then turns in a southeast, northeast, and southeast direction to the south edge of figure 5 (south of Twin Groves-near southeast corner). McKinney Creek flows in a southwest and west direction across the northwest corner of figure 5 and west of figure 5 flows in a northwest and south direction to join northwest, west, and south oriented Muddy Creek, which flows to the Little Snake River. The north and northwest oriented Muddy Creek in the northwest quadrant of figure 5 is a McKinney Creek tributary and is a different Muddy Creek and should not be confused with the Muddy Creek that McKinney Creek flows to. The northwest oriented Muddy Creek McKinney Creek flows to originates as a west oriented stream near the west edge of the southwest quadrant of figure 5. The southwest oriented stream in the southwest quadrant of figure 5 originating near the continental divide is McCarty Creek, which joins south oriented Little Savery Creek near the south edge of figure 5 (west half). Note how the south oriented Little Savery Creek headwaters and the northwest oriented Muddy Creek headwaters originate in the same region. South of figure 5 Little Savery Creek flows to southwest and south oriented Savery Creek, which then flows to the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. North and east of the continental divide Sage Creek originates in the Sage Creek Basin and then flows in a northeast and north-northeast direction to the north edge of figure 5 (east half). North of figure 5 Sage Creek joins the north oriented North Platte River with water eventually reaching the Gulf of Mexico. A northeast to southwest oriented through valley links the northeast oriented Sage Creek headwaters valley with the southwest oriented McCarty Creek headwaters valley. The through valley appears to be defined by at least three contour lines on the west and by more contour lines on the east side and is at least 40 meters deep and was probably eroded by southwest oriented flood flow moving to the Little Savery Creek valley. However, some other interesting shallow southwest to northeast oriented through valleys just to the west may have been eroded by northeast oriented flood flow moving into the Sage Creek Basin. If so the floodwaters had been moving in a southeast direction on the present day northwest oriented Muddy Creek alignment (west of figure 5) and were captured by headward erosion of the deeper northeast oriented Sage Creek valley (which probably occurred when southwest oriented flood flow on the Sage Creek alignment was beheaded and reversed). If correctly interpreted the Sage Creek Basin was eroded by flood flow that had been moving in a southeast direction to the south oriented Little Savery Creek valley, but which was captured and diverted in a northeast direction by the deeper northeast oriented Sage Creek valley.

Detailed map of Sage Creek-McCarty Creek drainage divide area

Figure 6: Detailed map of Sage Creek-McCarty 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 Sage Creek-McCarty Creek drainage divide area seen in less detail in figure 5. The map contour interval for figure 6 is 40 feet. The continental divide is shown with a brown dashed line extending in a south direction from the north edge of figure 6 (west half) to the southwest corner of section 32 and then in a southeast direction to section 10 and finally in a northeast direction to the east center edge of figure 6. The “Basin” in section 28 (located east and north of the continental divide) is the Sage Creek Basin. Little Savery Creek originates in section 6 and flows in a south-southwest direction to the southwest corner of figure 6. South and west of figure 6 Little Savery Creek flows to south oriented Savery Creek, which then flows to the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. McCarty Creek originates in section 5 and flows in a south-southwest, west, and southwest direction to the south edge of figure 6 (west half) and south and west of figure 6 joins south oriented Little Savery Creek. Sage Creek originates in section 32 and flows in a northeast direction to the small reservoir near the north edge of figure 6 and north of figure 6 flows in a northeast direction to join the north oriented North Platte River with water eventually reaching the Gulf of Mexico. A northeast to southwest oriented through valley near the west edge of section 4 links the south-southwest oriented McCarty Creek headwaters valley with a north-northeast oriented Sage Creek tributary valley. The through valley floor elevation is shown as being 7948 feet. Elevations near the southwest corner of section 4 reach 8158 feet and elevations at the northwest corner of section 5 reach 8166 feet. These elevations suggest the Sage Creek-McCarty Creek through valley is more than 200 feet deep. The through valley was probably eroded by south-southwest oriented flood flow moving from the present day north oriented North Platte River alignment to the south oriented Little Savery Creek and Savery Creek valleys. However, as mentioned in the figure 5 discussion it is also possible southeast oriented flood flow moving into the region on the present day northwest oriented Muddy Creek alignment (initially to the south oriented Little Savery Creek valley) was captured by headward erosion of the deeper northeast oriented Sage Creek valley and diverted in a northeast direction. Such complex flood flow movements were common during flood flow reversal events with floodwaters in one valley flowing in one direction and floodwaters in an adjacent valley flowing in the opposite direction.

Sage Creek-North Fork Savery Creek drainage divide area

Figure 7: Sage Creek-North Fork Savery Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 7 illustrates the Sage Creek-North Fork Savery Creek drainage divide area east and slightly south of figure 5 and includes a large overlap area with figure 5. The map contour interval for figure 7 is 20 meters. The east-west continental divide is shown with a labeled line extending from the west edge of figure 7 (north of center) to Twin Groves and then to Joes Park before reaching the south edge of figure 7 (east half). The Sage Creek Basin is located near the northwest corner of figure 7 and Sage Creek flows in a northeast direction from the continental divide south of Sage Creek Basin to the north edge of figure 7 (west of center). North of figure 7 Sage Creek flows to the north oriented North Platte River with water eventually reaching the Gulf of Mexico. Beaver Creek is the east-northeast stream turning near the northeast corner of figure 7 to flow in a south-southeast direction. East of figure 7 Beaver Creek joins east-northeast, east-southeast, and northeast oriented Little Jack Creek, which then joins north-northeast oriented Jack Creek. North and east of figure 7 Jack Creek joins the north oriented North Platte River. Willow Creek is a northeast oriented Little Jack Creek tributary and Spring Creek is a northeast and south oriented Willow Creek tributary originating near Twin Grove. Low Creek is an east-northeast oriented Little Jack Creek tributary north of Spring Creek. West and south of the continental divide the North Fork Savery Creek originates near the south edge of figure 7 (east half-just west of continental divide) and flows in a north direction toward Twin Grove before turning in a west direction to flow to the southwest quadrant of figure 7 where it turns again to flow in a south and southeast direction to the south edge of figure 7 (west half). South of figure 7 the North Fork Savery Creek turns to flow in a southwest direction to join other streams and to form south oriented Savery Creek, which then flows to the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. Fish Creek is a south oriented tributary to west oriented North Fork Savery Creek originating near the continental divide (west of the center of figure 7). The southeast oriented continental divide segment north and west of Twin Groves is crossed by shallow through valleys, which are best seen in the Fish Creek-Little Jack Creek headwaters area and Fish Creek-Low Creek headwaters area. These through valleys are evidence multiple flood flow channels crossed what is now the continental divide. The direction of flood flow is not obvious from figure 7 evidence and more detailed topographic map evidence is probably needed. However, based on previous discussions the initial flood flow was in a southwest direction, although it is possible after the flood flow reversal on the North Platte River alignment southeast oriented flood flow moving on the present day northwest oriented Muddy Creek alignment was captured by headward erosion of the north-northeast Jack Creek valley and its tributary valleys. If so headward erosion of the south oriented North Fork Savery Creek valley and tributary valleys beheaded the southeast and east oriented flood flow moving to the newly eroded Jack Creek valley and its tributary valleys at about the same time as headward erosion of the northeast oriented Sage Creek valley was capturing the flood flow further to the north and west. Next headward erosion of the south oriented Little Savery Creek valley and tributary valleys (west of figure 7) beheaded flood flow routes to the newly eroded North Fork Savery Creek valley and tributary valleys. Finally the southeast oriented flood flow to region was beheaded and reversed to create the northwest oriented Muddy Creek drainage route (west and north of figure 7).

Detailed map of Spring Creek-North Fork Savery Creek drainage divide area

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

Figure 8 provides a detailed topographic map of the Spring Creek-North Fork Savery Creek drainage divide area seen in less detail in figure 7. The map contour interval for figure 8 is 40 feet. The east-west continental divide extends in a south direction from the north edge of figure 8 (west half) to section 8 and then in a southeast and east direction into section 10 where it turns to continue in a south direction through section 15 to the south edge of figure 8 (east half). Willow Creek flows in a northeast direction from section 27 (in southeast quadrant of figure 8) to the east center edge of figure 8 and east of figure 8 joins Little Jack Creek, which flows to Jack Creek and then to the North Platte River with water eventually reaching the Gulf of Mexico. Spring Creek originates in the northeast corner of section 15 and flows in a northeast and east direction to the east edge of figure 8 (north half) and east of figure 8 joins Willow Creek. Low Creek originates in the north half of section 8 and flows in an east-northeast direction to the northeast corner of figure 8 and north and east of figure 8 joins Little Jack Creek. West of the continental divide Fish Creek flows in a south direction from the north edge of figure 8 (west half) to join west oriented North Fork Savery Creek in the southwest corner of section 18. West of figure 8 the North Fork Savery Creek turns in a south direction with Savery Creek then joining the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. Shallow through valleys cross the east-west continental divide and provide evidence of what were multiple flood flow channels that once crossed the region. The deeper through valleys as seen in figure 8 are defined by two contour lines on a side and are at least 40 feet deep. Floors of these deeper through valleys are in the 8000 to 8040 foot range. North of figure 8 the continental divide elevation rises to more than 8200 feet and continental divide elevations greater than 8200 feet can be seen near the south edge of figure 8. These elevations suggest a broader through valley that is at least 160 feet deep crosses the continental divide and the shallow through valleys seen in figure 8 are simply deeper channels eroded into the floor of the broader through valley. However the through valley or valleys are viewed large volumes of water once flowed across the present day continental divide. Probably the flow was initially in a southwest direction from the present day north oriented North Platte River alignment to the present day south oriented Savery Creek valley. However as previously mentioned the reversal of flood flow on the North Platte River alignment may have triggered the headward erosion of deeper northeast oriented tributary valleys, which captured southeast oriented flood flow that had been moving into the region on the present day northwest oriented Muddy Creek alignment. If so, the final flood flow movements across the continental divide may have been in a northeast direction.

McLain Creek-East Fork Savery Creek drainage divide area

Figure 9: McLain Creek-East Fork Savery Creek drainage divide area. United States Geological Survey map digitally presented using National Geographic Society TOPO software.

Figure 9 illustrates the McLain Creek-East Fork Savery Creek drainage divide area south of figure 7 and there is an overlap area with figure 7. The map contour interval for figure 9 is 20 meters. The east-west continental divide is a labeled line and extends from the north edge of figure 9 (east half) to the south edge of figure 9 (east half). Jack Creek originates near the southeast corner of figure 9 and flows in a north-northwest and north-northeast direction to the northeast corner of figure 9 and north and east of figure 9 joins the north oriented North Platte River with water eventually reaching the Gulf of Mexico. McLain Creek originates east of Divide Peak and flows in a northeast direction through McLain Park before flowing in a north-northeast direction to join Jack Creek near the northeast corner of figure 9. West of the continental divide Savery Creek is the southwest oriented stream flowing to the southwest corner of figure 9. South and west of figure 9 Savery Creek flows in a south direction to join the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. The East Fork Savery Creek originates near the south edge of figure 9 on the west side of the continental divide and flows in a north-northeast and northwest direction parallel to the continental divide before turning to flow in a west, northwest, and southwest direction to join southwest oriented Savery Creek. Jim Creek is a south-southwest oriented East Fork Savery Creek tributary located south of Divide Peak. A northeast to southwest oriented through valley on the southeast side of Divide Peak links the northeast oriented McLain Creek headwaters valley with the Jim Creek valley. The through valley floor elevation is between 2620 and 2640 meters. Divide Peak reaches an elevation of 2771 meters and elevations along the continental divide to the south rise much higher suggesting the through valley is at least 130 meters deep. The through valley was probably eroded by southwest oriented flood flow moving from the present day north oriented North Platte River alignment to the southwest and south oriented Savery Creek valley. Southeast oriented flood flow across the McLain Creek-Jim Creek drainage divide probably ended as ice sheet related crustal warping raised the Sierra Madre Mountains and floodwaters eroded deeper flood flow channels to the north and west. At some point in the process the direction of flood flow on the North Platte River alignment was reversed, which ended all flood flow to what had been actively eroding Savery Creek headwaters and tributary valleys.

Detailed map of McLain Creek-East Fork Savery Creek drainage divide area

Figure 10: Detailed map of McLain Creek-East Fork Savery 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 McLain Creek-East Fork Savery Creek drainage divide area seen in less detail in figure 9. The map contour interval for figure 10 is 40 feet. The east-west continental divide is shown with a labeled dashed line and extends in a southwest direction from the north edge of figure 10 (east of center) to the east half of section 3 (east of Divide Peak) and then in a south-southeast direction to the south edge of figure 10 (east half). Jack Creek is located east of the continental divide and flows in a north-northwest and north-northeast direction from the south edge of figure 10 to the north edge of figure 10. North of figure 10 Jack Creek flows to the north oriented North Platte River with water eventually reaching the Gulf of Mexico. McLain Creek originates in section 2 (east of Divide Peak) and flows in a northeast and north-northeast direction to the north edge of figure 10 (east half) and joins Jack Creek north of figure 10. South and west of the continental divide the East Fork Savery Creek flows in a northwest and west direction from the south center edge of figure 10 to near the southwest corner of figure 10. West of figure 10 the East Fork Savery Creek joins southwest and south oriented Savery Creek, which flows to the west and southwest oriented Little Snake River with water eventually reaching the Pacific Ocean. Jim Creek originates in section 10 and flows in a south-southwest direction to join west oriented East Fork Savery Creek. A northeast to southwest oriented through valley in the northwest corner of section 11 links the northeast oriented McLain Creek valley with the south-southwest oriented Jim Creek valley. The through valley floor elevation is between 8600 and 8640 feet. Divide Peak in section 3 rises to 9091 feet. Elevations along the continental near the south edge of figure 10 rise to 9018 feet and south of figure 10 exceed 10,000 feet. These elevations suggest the McLain Creek-Jim Creek through valley is at least 450 feet deep. Another slightly shallower through valley in the northwest quadrant of section 13 links an east-northeast oriented Jack Creek tributary valley with a west-southwest oriented East Fork Savery Creek tributary valley.  These and other through valleys crossing the present day continental divide are water-eroded valleys and were probably eroded by southwest oriented flood flow moving from the present day north oriented Jack Creek alignment to the west oriented East Fork Savery Creek alignment. At the time floodwaters eroded these valley the Sierra Madre Mountains were beginning to emerge and the regional topography looked very different from how it looks today. In time Sierra Madre Mountains emergence ended flood flow across the present day continental divide and flood flow along the Jack Creek alignment was reversed to create the north oriented Jack Creek drainage route.

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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