Earth 96339 - An Alternate Earth
Reply With QuotePoint of Divergence 1: Australia and Antarctica Don’t Separate.
Time: 100-95 Ma
Causes:
The Indian Rift that originally split Australis into Antarctica and Australia ends up failing, and thus, allowed Sahul to stay together.
In addition, a new rift ends up happening between Antarctica and South America, sending Shaul upwards.
Effects:
Despite the Indian Rift failing in terms of Australia and Antarctica, a new rift forms in its place at around 85-80 Ma. A rift that splits East Sahul, which is more where Zealandia would be, from Sahul.
Zealandia ends up emerging as two separate plates/parts, the Northern Zealandian Plate and the Southern Zealandian Plate. But as they rift, their eastern parts end up building up, while erosion happens in the West.
However, after a short while, they both end up rotating and moving up alongside Sahul, building up mountains and crust.
A small island arc of Zealandia ends up splitting from the two islands, and with the Pacific Oceanic Plate, there ends up being a chain of oceanic plateaus, island arcs, and igneous rock on the Pacific Plate’s borders with the Sahulian and the Zealandian plates.
Broken Ridge and Kerguelen don’t end up separating and end up as one singular oceanic plateau, and after a series of buildups, the united Kerguelen ends up mostly being above water.
New Guinea ends up connected with Sahul, just barely though.
A new shield can be seen in Sahul, stretching across the continent.
What’s left of the Sahulian side of Zealandian rift is lowland terrain with some islands, like Marie Byrd island and Tasmania, although they may be modified.
As a result of the rift of Antarctica-America, Sahul ends up moving north to where Papua New Guinea is about where it is today, maybe a little higher.
Point of Divergence 2: A new rift appears in North America, splitting Laramidia from Laurentia.
Time: 110-105 Ma
Causes:
The brief split of North America ends up becoming permanent, due to a rift between Laramidia and Laurentia, splitting the two continents away from each other.
Effects:
Thanks to the Mid Atlantic Rift not yet affecting the North Atlantic, Laurentia ends up briefly reconnecting with most of Europe. This ends up uplifting most of the mountains and land, which this event was known as the Grenville Rebirth.
But eventually, the Mid Atlantic Rift caught up to them, thus splitting Laurentia from Europe. However, the uplift caused by the collision allowed Northern Europe, East Laurentia, and Western Europe to end up rising more out of the ocean. Here are some examples:
Britain: Both Britain and Ireland end up being connected.
A new island chain from Iceland ends up in between Britain and Scandinivia.
Greenland, Britain, Scandinavia, and Ireland end up more elevated.
The Greenland and Quebec mountains end up more elevated.
As for Laramidia, the moving of the Western part of the North American plate, now known as the Laramidian plate, ends up accelerating towards Eurasian plate even more. Allowing places like Beringia, Eastern Siberia, and Kamchatka to rise more out of the ocean. Laramidia itself ends up further west in OTL’s West Coast.
The North America Rift ends up affecting South America too, but it doesn’t actually split, but it does end up creating the Amazon Sea, an inland sea in South America that splits the North andes from it, while also taking lowlands from the Amazon region.
This rift attempt across the Americas will be known as the Great American Rift.
Point of Divergence 3: The East African Rift ends up happening a lot earlier.
Time: 90-80 Ma
Causes:
As a byproduct from the rift of India, East Africa ends up splitting as well. However, it doesn’t entirely split off.
Effects:
This partial split ends up making the way for a new Gulf in Eastern Africa near Mozambique and Tanzania, which ends up providing for new rivers, lakes, and moisture.
Madagascar ends up moving further east, by not too much. However, the sunken islands near it end up being risen.
Other Geographical Changes:
The Balkan Oceanic Crust, which today has the Balkans and Italy, ends up rifting and connecting with Africa instead of being caught between it and Europe. After that, a new rift splits off the Balkan Microcontinent from Africa, and towards Europe. Forming a much bigger Alpine orogeny, and leaving some of its Southern parts to be more built up, even a part of Northern Tunisia and Algeria becomes an island between the Balkans and Northern Africa.
Africa and Arabia end up not colliding with Asia as much, leaving the middle east to be more of an archipelago.
Arabia never ended up rising out of Africa, leaving it to be with the continent, and the Tethys Sea to survive.
There are numerous lakes across North Africa and Arabia, such examples include Lake Chad, Lake Congo, the Maghreb Sea, and Lake Fazzan, splitting what would be the Sahara, into smaller pits of desert.
The biggest gain of all, is a new inland sea that sticks out into modern Nigeria that stuck around.
