Making waves at the Brough of Birsay The Brough of Birsay on mainland Orkney was a Viking stronghold 1,000 years ago. 380 million years before that it was a huge inland lake in the Southern Hemisphere. Here are the fossilised ripples to prove it. Share this:Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Pinterest (Opens in new window)Click to email a link to a friend (Opens in new window) Related Feel free to leave a Reply :) Cancel reply