The layered stack of Doonbristy Rock is a stunning sight along Ireland's north coastline. It's also known as the Rock of Dan Bristy or Dun Briste. The layers of this sea stack are sedimentary and were formed around 350 million years ago in the ocean off a passive margin boundary. Passive margins form where continents meet oceans if there are no active plate boundaries … [Read more...] about Doonbristy Rock: A Stunning Product of Ancient Geologic Processes and Modern Ocean Force