Porcellanous limestone in Chapel-le-Dale

[Pitlamp]

Langliffe - dunno - but next time you're up there maybe quietly chip a tint bit off and see what the fresh fracture looks like? (With your geological knowledge I'm sure you don't need further explanation.)

We did that a couple of weeks ago - it certainly looked like it. I was just thinking that if anybody else could confirm it, then it would a good place for those interested to see what it looks like.

I finally got round to having a look at this t'other day. I wasn't entirely sure which boulder you mean - but if you walk up-dale from the turn off to Braida Garth there are six boulders in a line along the verge on the right. (These boulders are clearly seen on Google Earth.) The final one, immediately before the long layby on the right, is classic porcellanous limestone. It's got the characteristic calcite "fenestrae" and has several pretty fresh surfaces, allowing it to be easily identified with a geological hand lens (but without having to knock it about with a hammer).

So yes - great point Langliffe - if anyone wants an easy location to view porcellanous limestone, this fits the bill.

 

[langcliffe]

The final one, immediately before the long layby on the right, is classic porcellanous limestone.

That's the one.

 

[ahinde]

I think there may be an exposure of porcellanous bed at High Brae in Ribblesdale. I came across some samples whilst walling a gap on the lower wall of High Brae within the Ingleborough NNR. I later traced the source of the stone to an area of small cliff edges at SD 794734. It fractures in the concoidal fashion, but does have a certain sparkle on some facets. This site needs confirmation from a qualified rock sniffer.
cheers
andrew

 

[Ian Ball]

Gives a reason for a fell run for Pitlamp