It tipped a little downward and hung balancing for a long instant, slowly returned, rocked slightly, groaned, and settled back to its former position.
Venters divined its significance.

It had been meant for defense.

The cliff-dwellers, driven by dreaded enemies to this last stand, had cunningly cut the rock until it balanced perfectly, ready to be dislodged by strong hands.

Just below it leaned a tottering crag that would have toppled, starting an avalanche on an acclivity where no sliding mass could stop.

Crags and pinnacles, splintered cliffs, and leaning shafts and monuments, would have thundered down to block forever the outlet to Deception Pass.
"That was a narrow shave for me," said Venters, soberly.