Cretaceous Boulders strewn across a plain on James Ross Island, Northern Peninsula. They were formed 70-90 million years ago in ancient sediments, created by a process similar to the formation of pearls, where layers of material cover a central nucleus. For the oyster, this core is a grain of sand. For the boulders, it was a fossil shell, bone fragment, or piece of wood.
James Ross Island, Antarctic Peninsula