Rock, regardless of size, has natural fissures (faults) throughout its structure.

Jenise was shocked to see someone emerge from the side of one of the boulders through a natural fissure.

"It looks like a natural fissure in the bone," she said, keeping her voice neutral.

In anatomy, a hiatus is a natural fissure in a structure.

This was no natural fissure in the rock but an established passage.

There must be some natural fissure communicating with the outside of the mountain, in a place where no one would see the men coming out.

The fort is located on a rocky promontory accessed over a natural fissure.

Emeralds containing natural fissures are sometimes filled with wax or oil to disguise them.

"Is it a natural fissure in the rock, or has it been dug out?"

According to a number of archaeologists, the shaft is simply a widening of a natural fissure in the rock.