Fearful Rock by Manly Wade Wellman

Manly Wade Wellman (1903–1986) was an American writer of science fiction and fantasy stories, which frequently appeared in such pulps as Astounding Stories, Startling Stories, Unknown, and Strange Stories. Wellman is best remembered as one of the most popular contributors to the legendary Weird Tales, and for his fantasy stories set in the Appalachian Mountains, which draw on the native folklore of that region. Karl Edward Wagner referred to him as “the dean of fantasy writers.”

 Fearful Rock is a novel that ran as a 3-part serial in Weird Tales in 1939.