Not stupid at all gattiweb. Particularly because I have thought along similar lines myself. I think it's just because the really simplified diagrams that we are provided do not go into much detail on such matters. There is this big beige layer going down 4Km. which comes to a long fat brown area with crosshatching in it and a couple of vertical double lines coloured in blue which are wells with up or down arrows. OK. It gives the general idea. Getting back to your areas of concern & mental images I have thought of the granites sometimes as being like a gigantic 'Malteser'. The honeycomby stuff being the porous granite while the chocolate coating being what keeps the liquids in! yesss!! Well maybe not quite right. If you pumped the internals of your malteser up and delivered a sharp pessure shock into it would the chocolate crack open? Quite possibly. Strewth. What then? Possibly, over millennia, water has permeated the granite and then, repeatedly, been drawn out again due to some changing conditions and the interface of the granite and substrates have become clagged up with sediments, maybe fine granite particles, and an impervious layer has formed around it all completing our malteser. I imagine Doone Wyborn, Bertus DeGraff and many others have lost sleep over the years wondering about all this. Then again maybe the 'oilers' have sussed it out long ago. It would be nice to know more.
geojac
RNE Price at posting:
0.0¢ Sentiment: Hold Disclosure: Held
