Great Lakes Earth Map

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Great Lakes Earth Map

Postby JohnWarrenDaileyGLE » Tue Oct 23, 2018 10:34 pm UTC


Dark brown=mountains. Light brown=uplifts. Black=Igneous provinces still visible today at their original extent with no consideration of erosion.

The Americas
The Appalachian Range used to exist, but all that remains nowadays are their metamorphic bedrocks. Since then, the Atlantic Coast is a labyrinth of islands, straits, channels and sounds, making New England the eastern equivalent of the Inside Passage, caused by five million years of being repeatedly scraped and bulldozed by ice. The terrain is not quite dramatic, the tallest above sea level being only 122.2 feet (37.25 meters.)

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 55 million years ago as the result of a collision between eastern and western North America. They stopped becoming active as recently as nine million years ago. Since then, a series of faulting had shed off the mountains’ sedimentary skin and exposed the tougher granite-and-gneiss core. 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 stands an uplift varying in elevation above sea level between 2,000 and 13,000 feet (between 610 and 3962 meters.)

Minor differences in geological history could create major differences in geographical shape. Without the Cascades or the Alaska Range, the distinctively whiplike Alaskan Peninsula simply does not exist. The area we’d recognize as San Andreas (Baja Peninsula and southwestern California) is fused into what we’d call southeastern Alaska. Evidence in the rocks beneath the soil shows that San Andreas did indeed collide with Alaska only 24 million years ago, but the mountain-building period did not last long, and the peaks were reduced into quarter-mile-tall hills.

The Black Hills of South Dakota don’t exist on Great Lakes Earth. The Ozarks, larger in area and elevation than back home, are the closest analogy. The tallest stands 7242 feet (2207 meters) above sea level. They started life as a dome of granite that, over millions of years, had been replenished with fresh supplies of magma. This allowed the crystals that made the granite dramatically larger, making the rock itself a lot harder. After 2.2 billion years under the surface, the dome popped above sea level only as recently as 20 million years ago. Even though rain and river played a part in carving the dome into numerous spires, pillars and gorges, the real player in shaping the Ozarks is lower air pressure, exfoliating the surface into pieces like layers of onions.

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 series of rifts and faults that failed to split the continent. The valley wouldn’t become a lake until the ice bulldozed the depressions during the Pleistocene glaciations.

West of the Rockies, there are even more lakes—Bonneville, Carson, Olympia, Hamilton and Red Deer. All of them formed separately late during the Cenozoic as tectonic weaknesses sank the land, sometimes to the point below sea level. Further shaping the lakes were the last five million years of ice ages strengthening and weakening the freeze-thaw cycles. As a result, not only do they have their distinctive shapes, they are also deep. Bonneville, the deepest, is currently over a thousand feet deep.

What we’d presume to be the Brooks Range in northern Alaska actually isn’t. The Murchison Mountains, as we call them, are actually volcanic peaks standing 14,411 feet (4392 meters) above sea level at the tallest. They stand at one of the points where the Arctic Plate sinks beneath the Laurasian Plate.

The Yellowstone mantle plume is still present. Except that instead of Wyoming’s northwestern corner, it can be found in northeastern California. The upland itself covers an area of 5,000 square miles and stands almost like an island between the surrounding lakes and lowlands.

Five million years ago, the oceanic Panamanian Plate had been invaded on both fronts—by the Caribbean Plate in the northeast and the Pacific Plate in the southwest. This uplifted the basaltic slab to above sea level and had volcanoes guarding the plateau. The Twins, as they are called, are still active. One twin is currently 6,684 feet above sea level, the other 9,698 feet. Curiously, the Twins make up the coastline of Central America on Great Lakes Earth, which makes sense considering their young age. What doesn’t make sense is how they could be so tall in so short a time. The same problem is said of the Andes, which also make up South America’s entire western coastline. But if we look at a bathymetrical map, we start to understand why—from Argentina to Guatemala, the Pacific Plate is paralleled by the younger, narrower Nazca Plate. It first formed only ten million years ago and uplifted the Andean coastline for five million years before reaching the Panamanian Plate. This double-subduction may explain why the Andes, 25,122 feet above sea level and still rising, as they have been for the last 45 million years, had such devastating eruptions in the last 10,000 years, with an average of one eruption measuring eight on the VEI every thousand years.

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 recognizable peninsulas. On Great Lakes Earth, the body we’d recognize as the Baltic Sea is actually known as the Baltic Plain.

The dominating feature of Asia is a large region of basaltic rock, the Siberian Traps. It formed as a series of eruptions spewed out lava 60 to 43 million years ago. Since most of northern Asia was a receding series of shallow seas at the time, the eruptions resulted in all four compositions of lava—low on both gas and viscosity, high on gas but low on viscosity, low on gas but high on viscosity and high on both gas and viscosity. However, 96% of those eruptions happened underwater, so they wouldn't react exactly like they would on land. Each eruption could last anywhere between 10,000 and 60,000 years, with breaks varying between 30,000 and 80,000 years. When the last eruption had finished, seven million square miles of Eurasia were buried under four million cubic miles of lava.

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 Indian to the east and the Atlantic to the west. 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.

The island of Newfoundland is the southeastern extension of Iceland. It stands at a point where a stationary mantle plume, loaded with silicon, stands at a crossroads between the Mid-Atlantic Ridge and the edge of the Arctic Plate. Unlike our Iceland, in which the Ridge has split it in east-west, the Iceland of Great Lakes Earth is split in a north-south division.

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 and the Malay Peninsula, don’t exist.

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 (10,210.8 meters) 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 between 65 and 70 million years ago.

65 million years ago, sub-Himalayan Asia was subject to a series of lava eruptions lasting a total of 30,000 years. When it was all over, the lava covered a thickness exceeding one mile, an area of one-and-a-half million square miles and a volume greater than one million cubic miles.

The islands of Japan on Great Lakes Earth are the result of multiple faults and subductive hot spots, stationary mantle plumes standing in the intersections of colliding plates. Japan, consisting of six large hotspots, stands three miles southeast of the Laurasian Plate and five northwest of the Pacific Plate. The fact that the mountains make up the coastlines suggest that Japan on Great Lakes Earth formed very recently—no longer, it’s been surmised, than 11 million years. Like the Andes, Japan was subject to massive, earth-destroying eruptions.

The Alps remain tall, as they are back home. However, they are formed as the result of a piece of Africa, known to us as Balk, colliding with southeastern Europe 40 million years ago. Currently, the range’s highest peak, Olympus, stands 22,838 feet (6961 meters) above sea level and is still rising. Behind the Alps is a plateau that covers lands we’d recognize as Romania, Moldova, Slovenia, Austria, Slovakia and Hungary. Also, Balk’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 northern Scandinavian coast, are the results of ocean/continent collisions — volcanoes. They are also taller than they are back home — 18,510 feet (5642 meters) above sea level and still rising.

The Ural, Caucasus, Pyrenees and Apennine mountain chains used to exist on Great Lakes Earth, but not anymore.

Like some of the other continents, Africa has its share of great lakes — Chad, Congo and Makgadikgadi. Lake Makgadikgadi, the southernmost, is also the youngest—100 feet (30 meters) at the deepest and formed as water flowing from the Aden Bahçesi inundated a series of fault lines only three million years ago.

The Atlas Mountains used to exist on Great Lakes Earth, but not anymore.

The defining mountain range of Africa is the Aden Bahçesi, which first formed 45 million years ago as the Indian Plate sank beneath the African Plate. Currently, the tallest peak stands 21,810 feet (6647.7 meters) above sea level and still rising.

Lakes Chad and Congo had a shared history. They originated less than 200 million years ago as a series of horsts and grabens that would quickly be inundated aftewards. It wasn’t until 80 million years ago, when the seafloor slowed down and sea levels began to recede, that perhaps the deepest points on Great Lakes Earth during the Cretaceous period became surrounded by dry land. In time, freshwater diluted the lakes, pushing the salinity deeper and deeper. Today, Lake Congo to the south averages 221 meters deep, with a maximum of 2001 meters, the bottommost 15 feet being brine. Lake Chad to the north has an average depth of 337.5 meters with a maximum of 3791 meters, with the Pharaoh’s Brine taking up the bottom 20 meters.

First and foremost, it’s not called “Australia” in Great Lakes Earth, but rather “Sahul”. The first major difference is the presence of Lake Eyre, a body of fresh water over 460,000 square miles in area and 49 meters at the deepest.

The northern and eastern coasts of Sahul are worth noticing. To the northwest, it looks as though the two main islands of New Zealand are glued into the mainland. It’d also look as though someone were shoving the island of New Guinea down the throat of mainland Australia, known geographically as the Gulf of Carpentaria. The northern and eastern extremes of Sahul are defined by volcanic mountains, the tallest standing 18,500 feet above sea level.

The final difference is that Sahul is much further south than Australia. So much so, in fact, that by comparison, the distance between it and Antarctica is cut by half.

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. But that is in our eyes only. On Great Lakes Earth, North America has always been a part of Laurasia for 250 million years.

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

There is another difference, one that applies also to the Southern Ocean surrounding Antarctica. Back home, the Arctic’s average depth is only 1205 meters, whereas its deepest point is 5,625 meters. The Southern Ocean averages 4,000 meters deep and has a maximum depth of 7,235. On Great Lakes Earth, the Arctic averages 663 meters deep with a maximum of 7235 meters, whereas the Southern Ocean averages 2212 meters deep with a maximum depth of 5625 meters.

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 straddling the coasts of Baffin Island, Alaska, and Scandinavia, creating the Scandes and the Murchison mountains.

Ocean Deep
Back home, the Pacific Ocean, the largest of the five, has an average depth of 4028 meters and a maximum of 10,924 meters. On Great Lakes Earth, the Pacific’s depth averages 2025 meters  and the maximum is now 8486 meters.

Back home, the Indian Ocean averages around 3963 meters deep with a maximum depth of 7258. On Great Lakes Earth, the Indian Ocean averages around 1467 meters deep and has a maximum depth of 7906 meters.

The Atlantic Ocean back home has an average depth of 3926 meters and a maximum of 8605 meters. On Great Lakes Earth, its average depth is now 1725 meters, and the maximum is now 10,911 meters, the same as the Pacific.

Originally, I had a list of questions per section, but after reading the Cassini site, let's simplify all the lists to one sentence--In this map, what would the wind and ocean currents look like using the information provided above?

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