What kind of rock is the Rock of Gibraltar in the Mediterranean Sea?

Gibraltar stands as the northern gateway to the Mediterranean Sea, and has historically been a much-coveted fortress for observing all the movement in and out of the area.

Despite its history as an impenetrable fortress, the Rock of Gibraltar consists almost entirely of soft gray limestone with a touch of shale thrown in for good measure.

Furthermore, it’s full of holes¬ómore than 180 caves carved by wind and rain in the deteriorating limestone.

We suppose it goes to show that “solid as the Rock of Gibraltar” is not so solid after all.