caused the big supercontinent, Pangea
, to split into a northern part, Laurasia, and a southern part, Gondwanaland
, about 250 million years ago
While moving north, Laurasia was itself split along a north-south rift, creating the Atlantic Ocean, that still grows by a few centimeters each year. This Mid-Atlantic Ridge cut right through the Laurasian mountain range now forming Newfoundland and Scotland.
(Information gratefully taken from
www.scotese.com and other Googled sources.)