There are some districts where the number and size of the erratics have given rise to the wildest legends of warlocks and elfins. Such a locality occurs between Carnwath and the river Clyde. Here, before farming operations were carried to the extent to which they have now arrived, large boulders, now mostly removed, were scattered so abundantly over the mossy tract between the river and the Yelping Craig, about two miles to the east, that one place was known familiarly as “Hell-stanes Gate” [road], and another “Hell-stanes Loan.” The traditional story ran that the stones had been brought by supernatural agency from the Yelping Craigs. Michael Scott and the devil, it appears, had entered into a compact with a band of witches to dam the Clde. It was one of the conditions of the agreement that the name of the Supreme Being should never on any account be mentioned. All went well for a while, some of the stronger spirits having brought their burden of boulders to within a few yards from the river, when one of the younger members of the company, staggering under the weight of a huge block of greenstone, exclaimed, “O Lord, but I’m tired.” Instantly every boulder tumbled to the ground, nor could witch, warlock, or devil move a single stone one yard further. And there the blocks lay for many a long century, until the rapacious farmers quarried them away for dykes and road-metal.
(The crags at Hare Law are called ‘Yelping Craigs’ on the modern OS map).
From Transactions of the Geological Society of Glasgow, v 1 pt2 (1863).