Concretions in Valtos Sandstone, Laig Bay, Eigg

 I'd seen these amazing cannonballs trapped in the Jurassic sandstone on a YouTube film. Thanks to this brilliant article, I was able to find them very easily. Go down past the Catholic church to the north end of the beach and there they are!!

The article explains how the sand grains are cemented by calcite deposits seeping through. There is even more detail in this brilliant piece about how the change from aragonite to calcite caused the change. And the idea that each ball took millions of years to form is mind-blowing!