In the latest Precambrian and early Paleozoic ,the supercontinent Rodinia, centered about the south pole, broke apart as blocks drifted northward. Most notable of these blocks were the large continents North America [Laurentia], Baltica, and Siberia.
North America lay isolated, stretched across the Cambrian equator. An arc approached from the south [east today] and Baltica and Siberia approached from the SE.
Tectonics, Sedimentation, Paleogeography of North Atlantic Region
1st Order Global Tectonic Features