The boulder came free of the ground and rested entirely on Conan's back.
Suddenly, a boulder in his path came loose and rolled down the rocky surface beside him.
It somehow made sense that we had to go to the place where the boulders came from, to keep the balance.
Just then several boulders came rolling into the trail ahead of them.
While descending the south face of the mountain a boulder came loose.
No matter what else happens before the end of the story, the reader will not be satisfied until the boulder comes to rest somewhere.
He streaked for cover as a huge boulder came plunging straight toward him.
The boulder came crashing down, straight at the group of mercenaries.
Those giant rocks and boulders had come to life!
After a couple of hours we passed round a huge boulder to come to a steep declivity leading down into a valley.