Great Lakes Earth: The Americas
The Appalachian Range, at first glance, doesn’t seem so different—low-lying hills covered in forest dominating the eastern landscape. However, they are taller—9,930 feet above sea level at the highest, compared to Mount Mitchell back home, which is over 6500 feet above sea level. Indeed, the Appalachians on Great Lakes Earth are a labyrinth of solid gneiss and granite, a macrocosm of the Black Hills and Yosemite, both of which we have but Great Lakes Earth doesn’t.
The mountains of the American West have some major differences. For starters, only the Rockies stand firm—no Coast Range, no Grand Canyon and most certainly no Sierra Nevada. The Rockies on Great Lakes Earth have a different road from ours. If we use it on our map, we’d see the Rockies starting in the Canadian village of Chesterfield and meandering to the next point, Rapid City, South Dakota. Once there, it makes another meander through the eastern borders of Wyoming, Colorado and New Mexico before making one last meander across the Texas-Mexico border. While our Rockies stand no taller than 14,440 feet above sea level, the tallest peak in a Great Lakes Rockies is measured to be 14,505 feet. Back home, our Rockies formed between 80 and 55 million years ago through the Laramide Orogeny, the subduction of the North American and Pacific Plates at a shallow angle. Their Rockies first formed 80 million years ago as the result of a collision between eastern and western North America. They stopped becoming active as recently as 30 million years ago. The main rocks of the range are schist, granite and gneiss, tough rocks with small vulnerabilities.
Behind the Rockies, which could vary in width between 75 and 300 miles, stands a plateau varying in elevation above sea level between 3600 and 8,000 feet. It covers what we would recognize as mainland Nunavut, Northwest Territories, Saskatchewan and Alberta in Canada; Montana, Idaho, Utah, Nevada, Colorado, Wyoming, Arizona and New Mexico in the United States; and Chihuahua, Durango, Coahuila, Nuevo León, Tamaulipas, Aguascalientes, Guanajuato, Querétaro, San Luis Potosí and Zacatecas in Mexico. Encrusting the plateau at the top is an igneous province of basalt, 200,000 square miles in area, the result of lava flooding western North America from 57 to 40 million years ago.
It is up north, from British Columbia to Alaska, that the iconic peaks of the Cascades stand firm. What we’d recognize as the Alaska Range in southern Alaska is an extension of the Cascades, turning the over-20,000-foot Denali into America’s largest volcano.
True to the spirit of the planet’s name, North America is full of large lakes. The largest of which is Agassiz. To have an idea on the shape, size and scope of Agassiz, we must look at the familiar faces of the Great Lakes—Superior, Michigan, Huron, Erie and Ontario—and then flood off the entire basin. This is Lake Agassiz, 95,000 square miles and 1500 feet at its deepest. Agassiz started out as a few tectonic depressions that expired some 20 million years ago. They wouldn’t become one lake until the ice bulldozed the depressions during the Pleistocene glaciations.
There are great lakes west of the Rockies as well. In fact, they could be identical to the lakes that used to dot the American West during the Pleistocene back home. Lake Bonneville is the largest—20,000 square miles in area and more than 1,000 feet at the deepest. Following Bonneville is Lake Lahontan, 8500 square miles and only 150 feet deep.
Comparing Great Lakes Earth to ours, we’d find that all land below sea level has become water, and Death Valley, the continent’s lowest and hottest point, is no exception. In its place is Lake Manly, a long but narrow strip of water fed by rivers flowing from Bonneville. It stretches only 50 feet long but gets no deeper than 600 feet.
The Yellowstone mantle plume is still present. Except that instead of Wyoming’s northwestern corner, it can be found in northeastern California. The latest eruption was roughly 10,000 years ago and it wouldn’t awaken again for another 600,000 years. The plateau itself covers an area of 5,000 square miles and stands almost like an island between the surrounding lakes and lowlands.
Comparing their South America to ours, there’s not much difference to find. The Andes themselves, though equal in length and width to our own, are taller and more active—the highest currently stands 30,111½ feet above sea level (not 22,841, as was the case back home) and the annual average of volcanic eruptions measures in at 50 per century.
How would these changes affect the Americas’ climate, weather and landscape?
How would they affect the danger zone called Tornado Alley?
Will the Midwest still be prairie?
Will the Wild West still be desert?
Will the Southeast still be swamp and forest?
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