Cliff face breaks off near climbers - GIF

[mklotz]

That is a thought provoking event.

It seems to take about 12 seconds for those rocks to make splash down into the water. A typical skydiver in a spread-eagle position will reach terminal velocity after about 12 seconds, during which time they will have fallen around 450 m (1,500 ft). This is not quite the same since the rocks were rolling down part of the way. They were way up there.

In free fall in a vacuum, we have...

d = 0.5 * g * t² = distance fallen in time t seconds under influence of gravity g = 32 ft / sec²

so, for t = 12 sec.

d = 16 * 144 = 2304 ft

This is an upper limit on the height from which they fell. Effects like rolling, air drag, etc. will decrease this height but we don't have any data to calculate those effects. For something dense like rock, drag is probably a small effect; rolling, who knows?