1.   The salt leaches out of some kinds of rocks and dissolves as water flows over them and erodes them down.

2.   This renders the soil toxic for about a year that it takes for salt to leach out of the ground, and is environmentally undesirable.

3.   The water vapor in their breath has caused salt to leach through walls and ceilings, creating cracks.

4.   Those who went inside Cheops, Chephren and Mycerinus contributed to a worsening water vapor problem that is causing salt to leach from interior stones and weaken them.