Why is some rock falling off the walls?
Before the excavation of the caves in 1937, the moisture that came through the walls was absorbed by the soil that was in the cave. The soil not only soaked up the moisture but acted as a structural support for the caves. Today there is nothing but the rock to soak up that moisture and that causes the stone to weaken and fall off. Today, archeological conservators are looking for ways to prevent further erosion of the cave walls.
Prior to the excavation of the caves in 1937 the moisture that came through the walls was absorbed by the soil that was in the caves. The soil not only soaked up the moisture but acted as structural support to the caves. Today there is nothing but the rock to soak up that moisture, causing the stone to weaken and fall off. Today archeological conservators are looking for ways to prevent further erosion of the cave walls.
Another method to save the cave may be to bring in gravel to raise the cave's floor up to its original line. Scientists believe this will slow down the erosion significantly, allowing moisture to travel through and evaporate out of the fill area rather than out of the surface of the rock. It will also help to support the already damaged cave walls. From: An interview with J. Claire Dean; From: Ken Oravsky Tour Content