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Tuesday, 8 May 2012

A bit of fieldwork

I went up Carningli today, and heard the cuckoo for the first time this season.  So all is right with the world.  He's so late this year that I thought he must have been shot by a violent Frenchman on his way over from the Congo.....

Some interesting samples that require more expert analysis than I am able to conduct.  Click to enlarge.

What I think we are looking at here:

1.  Bedrock from near the summit of Carningli -- dolerite

2.  Very coarse volcanic agglomerate / ignimbrite (??) from the southern flank of Carningli.  Not sure whether the outcrop is bedrock or a very large erratic.

3.  The strange rock found on the shore of the estuary, across the ricer from the Parrog, Newport.  Felsite, maybe from North Wales?  See my post dated 23 Feb.

4 - 8.  Erratics exposed during land clearance off the Cilgwyn Road, about a mile from Newport.

4.  Fine-grained grey igneous rock (or could it be sandstone?) -- knocked off a nice rounded boulder.

5.  Dark reddish marl -- from the Cambrian sandstone series?  Flaky -- almost a shale...  from a rough sub-angulat boulder.

6.  Medium-grained purple sandstone.  Cambrian?  From a nice rounded boulder. Origin -- SE Ireland?

7.  Fine-grained red sandstone.  Cambrian?  From a bigger rounded boulder.  Origin -- SE Ireland?

8.  Rough  greyish volcanic ash //agglomerate?  Has vesicles -- highly variable crystal structure.  From a large sub-angular boulder.  Don't think this is local.....

I don't think any of these will match with anything from Stonehenge -- but you never know.......

I await with interest the opinion of Myris of Alexandria and other ancient Egyptians........


Anonymous said...

Don't we have border controls to stop the entry of bellicose continentals (traveling from the Heart of Darkness or elsewhere in Africa) -or is anyone allowed in after a decent interval in the immigration queue.
One thing that long experience has taught me is that identifying rocks from photographs is a mugs game-it is difficult enough in the flesh. Be very wary of anyone who tells you otherwise (unless they are that very rare creature that can actually do it).
Plus, despite your instruction I cannot magnify the image.
As regards the collection of the material-whilst yours will be informed- context and systematics are everything (or of course for you lack of context is what you seek/erratics) for one swallow does not make a summer.
However just for you (and in that most unctuous of phrases beloved of American cop shows, (now affects Boston accent)) as a professional courtesy send them to me and I shall have a go at giving them names.
You have the address, a stones throw from the Pharos.

Anonymous said...


They're all pieces of stone.


BRIAN JOHN said...

Thanks Myris -- agree that you can't do much from photos -- no substitute for experience, a hand lens, and a little bottle of acid.

In this area, of course, erratics galore. On Salisbury Plain, more work needed, if only the Army would get out of the way....

P. M. said...


Caution is required when dealing with the acid, for one swallow doesn't quench the thirst.


Phil O'Sophical

BRIAN JOHN said...

A little dollop of hydrochloric does the trick, but I think I tried lemon juice once, and that worked very well too.....

Anonymous said...

I know glacial acetic acid does but the smell is something wicked.
It is almost impossible to get very small quantities of HCl for CO3 determination- certainly pharmacists ring MI6 when asked.
I shall try that (not ringing MI6 as -a few years ago I was interviewed by one such person at my home. I kept saying you are secret service and he kept saying no the armed services. He parked his car streets away (I followed him pretending to take my Peke for a walk, just to tease him).
I shall try it!
I do use clove oil rather than mineral oils when using oil immersion lenses with my microscopes-just for the smell, bit more viscous though.
Sweet smelling Myrtle !!!!.

BRIAN JOHN said...

Goodness -- this all sounds terribly exciting. All I ever did was pop a drop or two on the odd lump of rock to see if it was limestone....... and I was never bothered by the secret service.

Mind you, I did have a neighbour once who had a garden shed containing pot after pot of strychnine. He was a mole catcher, but when they took it away they said he had enough in there to kill off the whole population of Wales.

Anonymous said...

I'd be careful Brian!. Too much rocking the boat and we might hear on the news, that you've become a sexual deviant/contortionist and locked yourself inside your rucsac?. Perhaps that's the real task of Lt Col Facepalm and the RHA??

I'd hide under the bed for a few days.


Anonymous said...

Brian, I know that I've made some offensive comments about Myris on this blog in the past. But in the interest of establishing the truth, do you think that Myris could be persuaded to cast his expert eye over some of the visually erratic clasts I've excavated from our numerous Mendip hobbit holes??.

I hope that the photo's were of interest.


Anonymous said...

You should give him a Ring first.

I know he has strong views on amateur collections and indeed on amateurs but this side of the Grey Havens all is possible.
I believe his favourite chocs are crystalised gingers dipped in dark chocolate-any make- but LARGE size only.
Buy a box decant goodies refill box with 'stones' and send it plus decanted chocs.
Works EVERY time.

Anonymous said...

Test merchandise names. Ready your questions and answers.