Saturday, 1 December 2012

Dartmoor Granite

There's nothing quite like the unmistakeable look of weathered granite; Dartmoor's knobbly hilltops or 'Tors' are the exposed part of a massive granite intrusion known as a batholith. ("Excuse me, said the sedimentaries, we were here first, leave us alone." "No" said the granite.)  This was about 300 million years ago, when manners weren't as finely tuned.

No prizes for the three main minerals - feldspar, quartz and mica.  But who knows what the really big feldspar crystals are called?   Anyone?  You at the back?  Yes! "phenocrysts".  I didn't know that, either.

The Dartmoor tor shape was formed mainly around 50 million years ago during a time of hot humid climate (yeah, right) when intense weathering shaped the granite.

Dartmoor Granite Tor

Apparently, for the last 2 million years we have been in the grip of 'ice-age' conditions, with little bits of warmer weather in-between.  Well, I beg to differ.  I think a new geological era known as "Wetocene" should be recognised.  Let's face it, we are in the 'grip' of a maxi rain-age with little bits of dry in between.

No comments:

Post a Comment

Do leave a comment; it's always nice to know someone's out there.