The Norber Erratics are the finest example of glacial erratic rocks in Britain. Thanks to an unusual geological phenomenon, many of the dark ancient boulders are balanced, apparently precariously, on white plinths of limestone, forming marvelous natural sculptures.
The erratics are massive sandstone and slate Silurian boulders that were carried to their current location by a glacial ice sheet. They were deposited on the limestone shelf when the glaciers melted at the end of the last ice age, between 12,000 and 17,000 years ago.
The strange balancing act is the result of centuries of erosion that followed, whittling away the more vulnerable limestone except for in the protected areas directly below the older Silurian rock. There are over a hundred of these peculiar perched erratics scattered around the slopes of Ingleborough Hill in Yorkshire Dales National Park, with the slate boulders generally found higher up the hill than the sandstone.
Know Before You Go
There are various walking routes to the erratics field starting at the nearby village of Austwick. See this website for a map. The walk up the hill is moderately steep, but you are rewarded with excellent views at the top. The site is a popular place for geology student field trips; if you continue walking north past the erratics you will come across some of the best examples of limestone pavement in the area. When you have walked back into Austwick do not miss a pint at the Game Cock Inn. Open fire, great beer, and good food.