Avalonia

Avalonia was a microcontinent of the Paleozoic era that began as a volcanic arc on the northern margin of the ancient supercontinent Gondwana roughly 800 million years ago and collided with and attached to Gondwana about 650 million years ago. It then rifted away from Gondwana during the Late Cambrian and Early Ordovician, opening the Rheic Ocean in its wake, before its eastern portion collided with Baltica during the Caledonian orogeny and its western portion collided with Laurentia during the Acadian orogeny in the late Silurian and Early Devonian, with the whole fragment finally welded into the supercontinent Pangaea during the Variscan orogeny. Fragments of Avalonia's crust survive on both sides of today's Atlantic Ocean, including the Avalon Peninsula of Newfoundland, southern New Brunswick, Nova Scotia, Prince Edward Island, coastal Maine and New England in North America, and England, Wales, parts of Ireland, Poland, northern Germany, the Netherlands and Belgium in Europe.