Newfoundland in the Middle Cambrian (540 million years ago).
In the Middle Cambrian two ancient continents, Laurentia and Gondwana, were separated by the Iapetus Ocean. The Western Zone of Newfoundland lay on the eastern edge of Laurentia while the Eastern Zone was part of Gondwana. For those who study Greek mythology, you'll know that Iapetus, after whom this ancient ocean was named, was the father of Atlas, after whom the present-day Atlantic Ocean is named.

From Stephen Colman-Sadd and Susan A. Scott, Newfoundland and Labrador: Travellers Guide to the Geology (St. John's: Government of Newfoundland and Labrador, 1994).