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Tuesday, 19 March 2013

The joy of Geology


This is for Rob!  When I studied geology, I never did get the hang of that optical mineralogy stuff, but I quite liked the sedimentology and the fossils.

As I was clearing out some stuff from my study cupboard today, I came across these samples collected many years ago.  I thought they were rather splendid, and worth sharing.  Nothing whatsoever to do with either Stonehenge or the Ice Age........

 The "tuning-fork" graptolite is Didymograptus murchisoni -- found in the Ordovician rocks (dark grey or black shales -- old sea floor deposits) of the area.  The big one on the left of the photo is 7 cm long.

The most famous location for seeing these is Abereiddi, on the North Pembs coast west of Fishguard.  That's where I collected these samples.  The fossils are thought to be  circa 480 million years old.

2 comments:

MoA. said...

Brian the graptolite on the left is rather splendid. I have never had much luck with fossils, never ever found a bit of a vertebrate, nor a decent ammonite.
I taught transmitted light optics for over 30years followed by petrography. It was always the least liked or understood course but bl...dy good for them.
All gone now like tears in the rain.
No longer taught or rarely.
However without good petrography Rhosyfelin would be an unremarked outcrop of no interest and this blog the poorer.
MYRIS
M.

BRIAN JOHN said...

Amen to all of that, Myris. Thank goodness somebody is still doing it......