Etymology
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Laurentian 
in reference to granite strata in eastern Canada, 1854 (Sir W.E. Logan and T. Sterry Hunt), named for the Laurentian Mountains (where it is found), which are named for the nearby St. Lawrence River (see Laurence). Hence, Laurasia. The Laurentian library in Florence is named for Lorenzo (Latin Laurentius) de' Medici.
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Laurasia 
Paleozoic supercontinent comprising North America and Eurasia, 1931, from German (1928), from Laurentia, geologists' name for the ancient core of North America (see Laurentian) + second element of Eurasia.
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