I was talking with a geologist friend recently, who is not a caver, about some recent surveying, and they asked whether the survey had included notes about the geology of the different passages/pitches/cross sections. It didn?t, but the question made me think about whether it should have. I am interested in geology, but am not a geologist and know very little about it ? for those out there who do know geology: would it be useful to make notes on geology when surveying? If so, what observations should I record and what questions should I try to answer? I assume that collecting information about the different layers of rock, faults, dip, etc. around the cave would potentially allow some predictions about where best to push next in order to find more nice passage. Or can we derive all the same predictions just from looking at the plan/elevation of centre line data in Survex and seeing how all the passages are grouping?