A boulder tumbled over us to land out of sight with a loud thump.

More boulders tumbled loose and fell thunderously from keep to rock-strewn shelf.

A peculiar formation caught his eye: several huge boulders tumbled together, with a narrow, dark opening just visible between them.

A boulder, suddenly loosened, tumbled down so quickly that Philippe had no time to dodge.

One wall was now merely a wedged mass of broken stones, and several boulders had tumbled into the cave.

The wall trembled again, and several boulders tumbled into the cave.

A great boulder tumbled past the window and rolled away to crash up against the side of the crater.

The effort sent pain stabbing through my wounded leg, but the boulder teetered and then tumbled over.

Huge boulders had tumbled into the valley and obscured much of it from view.

Some were knocked to the ground, then flattened as the boulder tumbled past.