During the Ice Age when the British isles were all connected and joined to the European mainland, the English Channel was land through which a huge river flowed south from the convergence of the Thames and Rhine rivers in Atland, when the sea level was about three hundred feet lower, when the legendary city of Ys (or Ker Ys), now submerged in Douarnenez Bay of Brittany (western tip of France), flourished near where that huge river emptied into the Atlantic, and Heligoland (google Jurgen Spanuth) near the Elbe river to the north which flowed through Atland to empty into the Atlantic’s Norwegian Trench.
