 The underlying rock formation is known as Old Red Sandstone, which occurs from Dunnottar Castle five kilometres north to the town of Catterline seven kilometres south.This sandstone formation may be as thick as 2700 metres.In places the fissured red-and-green-coloured sandstone is replaced by picturesque conglomerate with roundish stones varying in diameter from two to thirty centimetres (historically known as "puddingstone" in this region of Kincardineshire).