laurensia present North American.......and of eurosia North of India subcontinent
Answers
Laurasia (/lɔːˈreɪʒə, -ʃiə/),[1] a portmanteau for Laurentia and Asia,[2] was the more northern of two minor supercontinents (the other being Gondwana) that formed part of the Pangaea supercontinent from c. 425 million years ago (Mya) to 200 Mya. It separated from Gondwana 215 to 175 Mya (beginning in the late Triassic period) during the breakup of Pangaea, drifting farther north after the split and finally broke apart with the opening of the North Atlantic Ocean c. 56 Mya.
Laurentia, Avalonia, and Baltica, and a series of smaller terranes, collided in the Caledonian orogeny c. 400 Ma to form Laurussia (also known as Euramerica and the Old Red Sandstone Continent). Laurussia then collided with Gondwana to form Pangaea. Kazakhstania and Siberia was then added to Pangaea 290–300 Ma to form Laurasia. Laurasia finally became an independent continental mass when Pangaea broke up into Gondwana and Laurasia.
Terminology and origin of the concept
Laurentia, the Palaeozoic core of North America and continental fragments that now make up part of Europe, collided with Baltica and Avalonia in the Caledonian orogeny c. 430–420 Mya to form Laurussia. In the Late Carboniferous Laurussia and Gondwana formed Pangaea. Siberia and Kazakhstania finally collided with Baltica in the Late Permian to form Laurasia.[4] A series of continental blocks that now form East and Southeast Asia were later added to Laurasia.
In 1904–1909 Austrian geologist Eduard Suess proposed that the continents in the Southern Hemisphere were once merged into a larger continent called Gondwana. In 1915 German meteorologist Alfred Wegener proposed the existence of a supercontinent called Pangaea. In 1937 South African geologist Alexander du Toit proposed that Pangaea was divided into two larger landmasses, Laurasia in the Northern Hemisphere and Gondwana in the Southern Hemisphere, separated by the Tethys Ocean.[5]
"Laurussia" was defined by Swiss geologist Peter Ziegler in 1988 as the merger between Laurentia and Baltica along the northern Caledonian suture. The "Old Red Continent" is an informal name often used for the Silurian-Carboniferous deposits in the central landmass of Laurussia.[6]
Several earlier supercontinents proposed and debated in the 1990s and later (e.g. Rodinia, Nuna, Nena) included earlier connections between Laurentia, Baltica, and Siberia.[5] These original connections apparently survived through one and possibly even two Wilson Cycles, though their intermittent duration and recurrent fit is debated.[7]
