How Does Great Lakes Earth's Geography Differ from Our Own?

In summary, the geography of Great Lakes Earth is different from our own. The American West has mountains that are different than those in our own region, and there are great lakes west of the Rockies as well.
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The geography of Great Lakes Earth, and the questions that come with it.


From 250 to 200 million years ago, all the continents had joined together to form a singular landmass called Pangaea.

The brown lines presented in the map are mountain ranges varying in height above sea level from 23,000 feet to 33,500 feet. The orange arrows are the directions in which the landmasses were moving which resulted in the mountain-building. The blue circle is, of course, 90 degrees South--the South Geographic Pole. The green circle is our best guess of where 0 degrees--the equator--would be situated.

The Americas
The Appalachian Range is nowhere to be seen.

The mountains of the American West have some major differences. For starters, only the Rockies stand firm — no Coast Range, no Grand Canyon, no Cascades, no Alaska Range and most certainly no Sierra Nevada.

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 20,310 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. No wonder, then, that transdimensional explorer Mark Greene called the Great Lakes Earth Rockies “a single, continuous spine of breathtaking Tetons.”

West of the Rockies, which could vary in width between 75 and 300 miles, stands a plateau varying in elevation above sea level between 3300 and 16,000 feet. Encrusting the plateau at the top is an igneous province of basalt, half a million square miles in area, 512,000 cubic miles in volume and over 6500 feet at the thickest, the result of lava flooding western North America 65 million years ago.

Without the Cascades or the Alaska Range, the distinctively whiplike Alaskan Peninsula simply does not exist.

The Black Hills of South Dakota don’t exist on Great Lakes Earth. The Ozarks, presented in black, are the closest analogy.

True to the spirit of the planet’s name, North America is full of large lakes. The largest of which is Agassiz. In fact, it is the cornerstone of all of Great Lakes Earth’s great lakes — enormous depressions, tectonic rifts or volcanic calderas reshaped and filled in by ice, rain and river. 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 5500 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. 80 million years ago, eastern North America collided with western North America, creating the Rocky Mountains. (Though to our eyes, they would've been a spine of Tetons as tall as Denali.) 65 million years ago, western North America became the setting of a horrifying series of flood basalt eruptions, one that totaled up to an area of 1,500,000 square miles, a volume of 512,000 cubic miles and a duration lasting ten to 12,000 years, more than fast enough to create the extinction of 60% of Great Lakes Earth's terrestrial species and 80% of its marine species.

Basalt may have resistance against water erosion. Against uplift, not so much. As the Rockies continued to rise, the increasing pressure buckled the Traps, creating cracks and weak spots that would one day be the lakes and rivers of western North America, Great Lakes Earth. Five million years ago, ice would have played their part, expanding the depressions into large lakes. Lake Bonneville, for example, is 1,000 feet at the deepest.

The Rockies stopped climbing as recently as 30 million years ago, right at the end of the Great Tectonic Uplift. The tallest peak then may have been as tall as Kailash now--33,500 feet above sea level. After 30 million years, the tallest peak is now 20,146 feet above sea level. Behind those rugged peaks is a plateau covering the lands we'd call Nunavut, Northwest Territories, Alberta, Saskatchewan, Montana, Idaho, Wyoming, Colorado, Utah, Nevada, Arizona, New Mexico, the Rio Grande River and finishing in the Mexican regions of Chihuahua, Durango, Sinaloa, Sonora, Coahuila, Nuevo León, Tamaulipas, Aguascalientes, Guanajuato, San Luis Potosí and Zacatecas.

The plateau gradually slopes westward, from 16,000 feet above sea level in Lamar, CO to 3300 feet in Tonopah, NV. (Topography presented in the map is not to scale.)


The Yellowstone mantle plume is still present. Except that instead of Wyoming’s northwestern corner, it can be found in northeastern California.


In the art of comparing Great Lakes Earth to ours, South America has the shortest list of differences.

The only difference between our Andes and their Andes is height — back home, Aconcagua stands 22,838 feet above sea level. On Great Lakes Earth, the highest peak is 28,251 feet above sea level, as tall as K2 back home. That smaller brown line snaking from Panama and through Colombia and Venezuela is the North Panamanian Twin, the point where the northwesterly-moving South American Plate consumes the basaltic Caribbean Plate. The tallest peak of the North Twin is 9,698 feet above sea level.


This map does not reflect ALL of South America’s rivers — just those with a minimum width of ten miles. Even so, that big blank in southern Brazil and Paraguay is the transition between northern and southern South America, a transition separated by 2,891 feet of elevation. That is because from 250 to 200 million years ago, South America’s southern half was part of an uplifted plateau much like Tibet back home. The more recent uplift of the Andes (no earlier than 40 million years) nearly attempted to resurface that past.

The average number of Andean eruptions is 50 per century, and most of those never exceeded VEI 3 (0.1 cubic kilometers of erupted tephra and an eruption column height varying between three and 15 kilometers).

Questions follow:

  • Are these changes enough to spare northeastern Nebraska from the onslaught of Tornado Alley without sacrificing the Midwest's prairie fertility in the process?
  • Will all these lakes and rivers turn the Wild West into a greener Eden?
  • How much of the Amazon Basin will be contained within South America?
  • What kind of landscapes should I expect to see in Argentina and Brazil?


Physically absent in the supercontinent are Turkey, Iran, and the Low Countries (Belgium, Netherlands, Luxemburg and Denmark). Back home, Scandinavia is one of Earth’s reconginzable peninsulas. On Great Lakes Earth, the body we’d recognize as the Baltic Sea is dry land.

The dominating feature of Asia is a large region of basaltic rock, the Siberian Traps. It formed as a series of flood eruptions spewed out lava 60 to 43 million years ago. The lava covered an estimated area of eleven million square miles and a volume of four million cubic miles.


Eurasia is subject to Great Lakes Earth’s largest sea, one that we used to have back home — the Tethys. Back home, the Mediterranean has an average depth of 1500 meters and a maximum of 5267. The Tethys’ depth is 1205 meters on average and 7,000 maximum. Even so, the ratio between deep and shallow water is remarkably similar to that of the Mediterranean — more or less than 45% of the sea is no deeper than 200 meters (the required maximum depth for a sea to be “shallow”). It’s also connected to two oceans with two different personalities — the warm Indian to the east and the cooler, nutrient-richer Atlantic to the west.


The island of Newfoundland is the southeastern extension of Iceland. It stands at a point where a stationary mantle plume stands at a crossroads between the Mid-Atlantic Ridge and the edge of the Arctic Plate.


What we’d recognize as the Arabian Peninsula is, on Great Lakes Earth, an extension of northeastern Africa, erasing both the Red Sea and the Gulf of Aden out of existence. This further widens the passage from the Indian Ocean to the Tethys.

In Asia, what looks to us like Borneo is a big extension of eastern India, erasing the Bay of Bengal from the map. Sumatra is an extension of India’s western coast. The rest of Indonesia, as well as the island chain of the Philippines, don’t exist. This leaves the Malay Peninsula dangling on its own.


Back home, the Himalayan range in Asia is impressive enough. On Great Lakes Earth, they are even more so. The highest peak, Kailash, stands 33,500 feet above sea level and still rising. If the base of Mauna Kea in Hawaii were above sea level, this would have been its equal. Their Himalayas are older than ours, if the differences in height suggest anything. Ours first formed 50 million years ago. Theirs rose from the plains 65–70 million years ago.

The islands of Japan on Great Lakes Earth are the result of subductive hot spots, stationary mantle plumes standing in the intersections of colliding plates. Japan, consisting of six large hotspots, stands a mile east of the Northern Plate (yellow) and three west of the Pacific (magenta).


The Alps remain tall, as they are back home. This time, though, the range’s highest peak, Olympus, stands at almost 23,000 feet above sea level and still rising. Behind the Alps is a plateau that covers lands we’d recognize as Romania, Moldova, Slovenia, Austria, Slovakia and Hungary. Also, the peninsula’s terrain on Great Lakes Earth consists of plains and hills rather than mountain ranges like back home.

The Scandes, stretching the length of the western Scandinavian coast, are the results of ocean/continent collisions — volcanoes. They are also taller than they are back home — almost 18,500 feet above sea level.

By contrast, the Ural, Caucasus, Pyrenees and Apennine mountain chains don’t exist on Great Lakes Earth.


Questions follow:

  • With open connections to both the Indian and the Atlantic, what would the Tethys' personality be?
  • Will a higher Himalayas—which means a higher Tibetan Plateau—pose any noticeable differences on India’s climate and precipitation?
  • With Japan’s volcanoes being a combination of hotspots (like Hawaii, Iceland and Yellowstone) and subduction (like Japan back home), would this combination pose any difference in Japan’s topography?
  • Would adding Borneo and Sumatra pose any difference to the climate and landscape of the Indian subcontinent?
  • With the rest of Indonesia and the Philippines out of existence, how would this absence affect ocean currents?
  • How would all this added water affect the Mediterranean Basin as well as the Indian monsoon?
  • Concerning the Siberian Traps, 40 million years of erosion would mean an altogether different Russian landscape, but to what extent? Would we still see vast, singular bands of boreal forests and steppes, or would we expect to see Russia hosting a wider variety of habitats?
  • How would the changes in mountain building and coastlining affect the climate and landscape of the rest of Europe?

To the naked eye, you may not see any difference between our Africa and theirs. However, like some of the other continents, Africa has its share of great lakes — in the Sahara, there are a handful, including Ahnot-Moyer, Fezzan, Chotts and Chad.


Long ago, a granitic plateau that would one day become North Africa was topographically uniform. Was. That was before the Great Tectonic Uplift, a global event lasting from 80 to 30 million years ago, when the mountains of modern-day Great Lakes Earth were being formed. The Atlas Mountains were a combination of fault-block, subductive and uplifted passive margins. The tallest peak stands 15,171 feet above sea level. The Jordan flows from the Atlas Mountains to Lake Fezzan. From Lake Fezzan slithers the Tigris, which flows to the brackish Lake Chotts. The Pishon flows from Lake Chad to the Jordan. The Gihon flows from Lake Chad to the longest river on Great Lakes Earth, the Nahar. The Euphrates flows from Lake Chad to Lake Fezzan before stopping near the Nahar's delta.

The Aden Bahçesi is a subductive range, akin to South America's Andes, only shorter--the tallest peak standing 21,810 feet above sea level--1500 feet taller than both Denali back home and the tallest of Great Lakes Earth's Rocky Mountains in North America. Flowing from the Aden is the Nahar, snaking through 3,000 miles of African jungles and savanna before finishing its journey at the Tethys coast.

Millions of years of uplift and faulting and depressing and erosion by humidity and rain had taken a toll on the ancient plateau, creating imperfections that lakes and rivers took full advantage of. The reason the rivers flowed north is that Africa's southern half has a higher elevation than the northern half, not just from the Aden's more extensive reach, but also due to the fact that from 250 to 200 million years ago, Africa's southern half was a vast plateau as tall as Tibet and extending to South America's southern half and the Antarctic Peninsula.

There is another great lake in Africa, this time south of the equator. Back home, the Okavango Delta, Lakes Ngami and Xau, the Mabambe Depression and the salt pans of Nxai, Sua and Nwetwe are all that remains of Lake Makgadikgadi, a vast body of water that covered an area of 50,000 square miles and 100 feet deep. In Great Lakes Earth, Makgadikgadi is still there, fed by the rivers Zambezi, Cuando and Okavango.

Questions follow:
  • Are any of these changes enough to turn North and South Africa from desert to more verdant habitat, maybe to the extent of feeding civilizations?
  • Would having a tropical megalake be enough to influence the equatorial climate of the Congo rainforest?
  • Would East Africa still be the cradle of human evolution, or do I have to look elsewhere?


First and foremost, it’s not called “Australia” in Great Lakes Earth, but rather “Sahul”. Those brown lines are Sahul's only mountain range, the Great Dividers. The tallest peak stands 7,310 meters--almost 24,000 feet--above sea level. The Dividers are formed when the northeastward-moving Sahulian Plate gobbles up the southward-moving Pacific Plate, and there can be only one result--volcanoes.

The biggest blue presented here is Lake Eyre, a body of fresh water 463,323 square miles in area and at a maximum depth of only 49 meters, it is one of the shallowest of the Great Lakes.

Sahul is further south, closer to Antarctica, than Australia--so much that the distance between it and Antarctica would, by comparison, be cut by half. That is over 1400 miles!

Questions follow:
  • Will the Outback still be desert?
  • In the same scenario, Indonesia and the Philippines don’t exist. What kind of ocean current(s) would one expect to see influencing Sahul?
  • What kind of climatic and ecological influences would we expect Lake Eyre and the continent's proximity to Antarctica to create?

Pole to Pole
Compared to our oceans, the Arctic Ocean of Great Lakes Earth seems to have a little elbow room. The reason — the Atlantic on Great Lakes Earth is wider than ours by over 1350 miles. Africa, Eurasia and Sahul have, compared to our Old World, moved that far eastward, creating a landbridge that connects Asia to North America, erasing the Bering Strait off the map and shrinking the Bering Sea. To that extent, it would be like turning the Russian urban locality of Egvekinot (66.3205 degrees North and 179.1184 degrees West) into the next-door neighbor of Teller, Alaska.

The island of Greenland is rearranged to the extent that Mont Forel, the island’s highest peak, is located in 90 degrees North — the North Geographic Pole.


There is a final difference, one that applies also to the Southern Ocean surrounding Antarctica. The ratio between average depth and maximum depth is the same as back home, but the numbers are different. Back home, the Arctic’s average depth is only 1205 meters, almost 4,000 feet, whereas its deepest point is 5,625 meters, 18,456 feet. The Southern Ocean averages 4,000 meters deep and has a maximum depth of 7,235. On Great Lakes Earth, the averages for the Arctic and Antarctic oceans are 1652 and 5280 meters, respectively.

The only difference their Antarctica has with our Antarctica is that volcanoes line the coasts of the lands of Oates, George V, Terre Adélie, Wilkes, Queen Mary, Wilhelm II and Princess Elizabeth.

Then, of course, there is the Arctic Plate, something that doesn’t exist back home. Horizontally cutting Iceland in half, we can find the border three to seven miles off the coasts of Labrador, Baffin Island, Alaska, Russia and Norway, creating chains of volcanoes that include the Scandes. Note that the Polar Atrial Ridge diverges east and west, pushing the outer boundaries of the plate to squeeze beneath the Northern Plate. The result — volcanic mountain chains varying in height above sea level from 15,776.7 to 19,341 feet.

Questions follow:
  • How would these differences affect ocean currents and polar landscapes?
  • Could any of these changes have influenced the global average temperature and precipitation? If so, to what extent?
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  • #2
Well, that has got to be one of the longest opening posts I've seen...

My questions all come from the very first paragraph, where I would have expected a little more explanation of the bigger picture here.

What is the premise for the existence of this different Earth?
Is this an alternate timeline for our Earth?
Or a coincidentally parallel development of some planet elsewhere in our universe?

And finally, it seems to have started out geographically identical, but diverged at some point from the development we are familiar with. When did it diverge? And what event(s) catalyzed the divergence?
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Likes chasrob
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And another.

For now, let's focus on the questions presented in the thread.

Related to How Does Great Lakes Earth's Geography Differ from Our Own?

What is "Great Lakes Earth (WHOLE)"?

"Great Lakes Earth (WHOLE)" is a term used to describe the five interconnected freshwater lakes located in North America: Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. These lakes are collectively known as the Great Lakes and are the largest group of freshwater lakes in the world.

What are the characteristics of the Great Lakes?

The Great Lakes contain approximately 21% of the world's surface freshwater and are known for their vast size, deep depths, and unique biodiversity. They are also an important source of drinking water, transportation, and recreation for millions of people.

How were the Great Lakes formed?

The Great Lakes were formed over 10,000 years ago during the last ice age. As glaciers receded, they carved out large depressions in the earth which eventually filled with water, creating the lakes as we know them today.

What are the major threats facing the Great Lakes?

Some of the major threats facing the Great Lakes include pollution from agricultural runoff, industrial waste, and urban development, invasive species, climate change, and over-extraction of water for human use. These threats can have a significant impact on the health and sustainability of the lakes and their surrounding ecosystems.

What can be done to protect the Great Lakes?

To protect the Great Lakes, it is important to implement sustainable management practices, reduce pollution and nutrient runoff, control invasive species, and promote conservation efforts. It is also crucial for governments, industries, and communities to work together and prioritize the preservation of these valuable freshwater resources.

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