I live in the country with dolomite slopes, a stream, and a wooded area. The land has abundant wildlife. When I was out on the land, I heard what sounded like children throwing rocks. I tracked the sound and discovered where a tree with exposed roots clings to a rocky cliff, with around an eight foot drop to the stream, an animal was making a burrow under the roots and trunk. It was digging furiously, as fresh dirt and stones went flying. The opening is large and deep. I can't get up to it to look in. What do you think it might be?

Many animals make burrows, so it is hard to tell without seeing the site myself. A large hole with the digging action you describe could possibly be a coyote excavating a den site.