Have a closer look, imagine a Storm, Sand piling up under those Boulders on the overhang, now imagine after the storm, winds from a different angle, the wind removed the sand and undercuts the Boulders, they begin to fall, where would they GO? Ahh!! Yes in those " channels" and rolling polling down those channels they cause more errosion, and THAT is WATER, hmmm, where is my Geology Book? ,,,,,,,danwill dodging the subject? your "boulder hypothesis" wouldn't explain why this is repeatedly observed in the equatorial latitudes only in the summer on sunward-facing cliffs. and they are being called "recurring linnae" because they are not certain that water is the cause. but water fits better than your explanation. !#264.2 - Wed Aug 10, 2011 4:18 PM EST Eagle Averro look up sublimation and surface tension changes due to it. !#264.3 - Wed Aug 10, 2011 5:06 PM EST