laurentia is the north american paleocontinent, which also includes present day northwest ireland, scotland, greenland, the north slope of alaska, and the chukotsk peninsula of ne russia. during the ordovician-devonian time, laurentia remained at the same paleolatitude, slightly south of the equator in the southern hemisphere, with relatively the same paleolongitude. major defining tectonic events include the neoproterozoic rift sequence from the breakup of grenville basement rocks, thermal subsidence related to the early cambrian to middle ordovician drift sequence during the opening of the iapetus ocean, the appalachian accretionary events to the eastern continental margin, and the resulting foreland-basin and clastic wedges.