EXAMPLES FROM THE WEB FOR HARD ROCK
Then he, too, relaxed on the hard rock and sank into heavy sleep.
Of course a hard rock must be selected, such as granite or trap rock.
They put the flint on a hard rock and struck it with a heavy blow.
There was also a hard rock, not far from our lodgings, split through.
Slowly, with powerful blows, he bores a hole in the hard rock.
The ground now was hard rock, not earth, and it rang under his steps.
Here he may have learned that the coney makes its dwelling in the hard rock.
Perhaps the hard rock was chiselled with tools of tempered copper.
He could not bury the body, for the ground was hard rock, and he had no tools.
The hammer bit its way slowly but surely into the face of the hard rock.