Morning comes, and the boar tracks are buried beneath a fresh layer of thick, pristine snow.

BBC: Poland's wild woods

Her evidence is that many of these layers contain animal burrows that seem to start at the surface of the layer, suggesting that the layer in question had been buried subsequently.

ECONOMIST: Some new ideas about why life on Earth has periodic crises

It must be buried under a mountain, sunk to the bottom of the sea, or placed under a thick layer of salt deep under a desert for instance.

FORBES: What Are The Most Important Things To Know/Understand About Nuclear Energy?