The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon a...The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.展开更多
Detailed topographic maps provide much of the information needed to understand how drainage divides like the southeast Wyoming Medicine Bow River-Laramie River drainage divide originated. Topographic map evidence for ...Detailed topographic maps provide much of the information needed to understand how drainage divides like the southeast Wyoming Medicine Bow River-Laramie River drainage divide originated. Topographic map evidence for each Medicine Bow-Laramie River drainage divide segment is here described and analyzed first using a commonly published interpretation (accepted paradigm) in which drainage routes developed on a surface of now mostly absent Oligocene and Miocene sediments that previous investigators have hypothesized to have once filled the Laramie Basin and to have also buried (or partially buried) the surrounding Laramie and Medicine Bow Mountains. Second, the same map evidence is analyzed using a recently proposed interpretation (new paradigm) in which massive and prolonged floods flowed across Wyoming as the Laramie and Medicine Bow Mountains began to be uplifted and as the southeast-oriented North Platte River valley eroded headward along the rising Laramie Mountains northeast flank. Low points along the drainage divide (referred to as divide crossings) are interpreted to be places where water once flowed across the drainage divide with the drainage divide being formed when capture events diverted the water in other directions. Valleys leading away from divide crossings are used to determine the nature of observed capture events, many of which are difficult or impossible to explain from the accepted paradigm perspective, but which are consistent with the mountain uplift, headward erosion of deeper valleys, and/or draining of floodwaters trapped in the Laramie Basin as the new paradigm predicts. However, the new paradigm requires a North American continental ice sheet heavy enough to raise entire regions and mountain ranges as massive and prolonged meltwater floods flowed across them, something the accepted paradigm does not recognize.展开更多
文摘The Laramie River after flowing in a north direction through southeast Wyoming’s Laramie Basin abruptly turns in an east direction to flow across the north-to-south oriented Laramie Range in a bedrock-walled canyon and eventually reaches the lower elevation Great Plains and southeast-oriented North Platte River. The North Laramie River, Bluegrass Creek, and North Sybille/Sybille Creek also flow from the Laramie Basin in separate bedrock-walled valleys into the Laramie Range before eventually joining the Laramie River. Bedrock-walled through valleys link the various Laramie Range stream and river crossing valleys and detailed topographic maps were used to determine how this anastomosing bedrock-walled canyon complex and the large escarpment-surrounded Goshen Hole basin (located just to the east of the anastomosing canyon complex) originated. Map evidence shows multiple streams of water must have diverged in the Laramie Basin from the north-oriented Laramie River to enter the Laramie Range before converging in or east of the Laramie Range and also shows how present day through valleys enabled diverging and converging streams of water to cross the Laramie Range. The anastomosing bedrock-walled valley complex studied here extends from north of the North Laramie River valley to south of the North Sybille/Sybille Creek valley. Large volumes of water flowing from the Laramie Basin to the Great Plains are interpreted to have eroded the anastomosing canyon complex and the “downstream” Goshen Hole escarpment-surrounded basin. Headward erosion of the north-oriented Sybille and Chugwater Creek valleys across large sheets of east-oriented water are interpreted to have left the Goshen Hole escarpment-surrounded basin as a large abandoned headcut. A water source was not determined, although a continental ice sheet that deeply eroded and warped the North American continent is considered to be a possible source.
文摘Detailed topographic maps provide much of the information needed to understand how drainage divides like the southeast Wyoming Medicine Bow River-Laramie River drainage divide originated. Topographic map evidence for each Medicine Bow-Laramie River drainage divide segment is here described and analyzed first using a commonly published interpretation (accepted paradigm) in which drainage routes developed on a surface of now mostly absent Oligocene and Miocene sediments that previous investigators have hypothesized to have once filled the Laramie Basin and to have also buried (or partially buried) the surrounding Laramie and Medicine Bow Mountains. Second, the same map evidence is analyzed using a recently proposed interpretation (new paradigm) in which massive and prolonged floods flowed across Wyoming as the Laramie and Medicine Bow Mountains began to be uplifted and as the southeast-oriented North Platte River valley eroded headward along the rising Laramie Mountains northeast flank. Low points along the drainage divide (referred to as divide crossings) are interpreted to be places where water once flowed across the drainage divide with the drainage divide being formed when capture events diverted the water in other directions. Valleys leading away from divide crossings are used to determine the nature of observed capture events, many of which are difficult or impossible to explain from the accepted paradigm perspective, but which are consistent with the mountain uplift, headward erosion of deeper valleys, and/or draining of floodwaters trapped in the Laramie Basin as the new paradigm predicts. However, the new paradigm requires a North American continental ice sheet heavy enough to raise entire regions and mountain ranges as massive and prolonged meltwater floods flowed across them, something the accepted paradigm does not recognize.
