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Where in the world does Gritstone occur?
I know you get it in the Peak , Yorkshire , Northumberland , Ireland and even North Spain.... where else?
I know you get it in the Peak , Yorkshire , Northumberland , Ireland and even North Spain.... where else?
In reply to Pkrynicki1984:
'Gritstone' is a very English thing. In geology it is an old and informal term (apart from it's use in the formal stratigraphic definitions by BGS).
It's a coarse grained sandstone and gravel conglomerate to the rest of the world.
'Gritstone' is a very English thing. In geology it is an old and informal term (apart from it's use in the formal stratigraphic definitions by BGS).
It's a coarse grained sandstone and gravel conglomerate to the rest of the world.
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In reply to Pkrynicki1984:
Click on Logbooks > Find Crag Map > Advanced Search > Rocktype, and select Gritstone. Have a play with various postcodes (unfortunately the map does not reflect the current filter, sch a shame). You'll find stuff all over.
North Wales has bits of gritstone as well, there's some gritstone slabs by the sea at Barmouth (and hard gritstone sea cliffs somewhere there too).
Click on Logbooks > Find Crag Map > Advanced Search > Rocktype, and select Gritstone. Have a play with various postcodes (unfortunately the map does not reflect the current filter, sch a shame). You'll find stuff all over.
North Wales has bits of gritstone as well, there's some gritstone slabs by the sea at Barmouth (and hard gritstone sea cliffs somewhere there too).
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In reply to Pkrynicki1984:
I recall Seb Grieve took a trip to Mongolia to climb something that was pretty gritstone-like. There was an OTE article I think.
I recall Seb Grieve took a trip to Mongolia to climb something that was pretty gritstone-like. There was an OTE article I think.
In reply to Toccata:
And what's he done on Mongolian grit?
> I recall Seb Grieve took a trip to Mongolia to climb something that was pretty gritstone-like...
And what's he done on Mongolian grit?
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In reply to SenzuBean:
It's not "proper" gritstone, more a coarse sandstone that has been optimistically called gritstone in most cases.
> Click on Logbooks > Find Crag Map > Advanced Search > Rocktype, and select Gritstone. Have a play with various postcodes (unfortunately the map does not reflect the current filter, sch a shame). You'll find stuff all over.
> North Wales has bits of gritstone as well, there's some gritstone slabs by the sea at Barmouth (and hard gritstone sea cliffs somewhere there too).
It's not "proper" gritstone, more a coarse sandstone that has been optimistically called gritstone in most cases.
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In reply to ianstevens:
It's pretty clear the OP was asking about coarse sandstones that have the same lithology, not just the Millstone Grit series.
> It's not "proper" gritstone, more a coarse sandstone that has been optimistically called gritstone in most cases.
It's pretty clear the OP was asking about coarse sandstones that have the same lithology, not just the Millstone Grit series.
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In reply to SenzuBean:
I was under the impression that the key feature of a gritstone in contrast to a sandstone is that it also has some larger clasts that are gravel sized, not just sand-sized clasts. When I stated coarse sand, I meant just that - it's actually a very precise technical term in sedimentology and sedimentary geology. Gravel clasts aren't present in all of the Welsh "Grit" that I've experinced.
I was under the impression that the key feature of a gritstone in contrast to a sandstone is that it also has some larger clasts that are gravel sized, not just sand-sized clasts. When I stated coarse sand, I meant just that - it's actually a very precise technical term in sedimentology and sedimentary geology. Gravel clasts aren't present in all of the Welsh "Grit" that I've experinced.
In reply to IanStevens - where does that leave Millstone then?
Dakota formation, and others in Colorado have some nice sands and gritstones, and are good for climbing. The surfaces are a bit rougher those as the weathering effects are different
Dakota formation, and others in Colorado have some nice sands and gritstones, and are good for climbing. The surfaces are a bit rougher those as the weathering effects are different
In reply to GarethSL:
Hmmm ...... that's a bit of an anglo-centric viewpoint!
There's gritstone in both North Wales and Central Wales. Geologically, most of it is older than Peak/ Pennine grit and lithologically it's on a continuum, locally varying from being a coarse sandstone to a medium coarse grit.
In North Wales it's found on Tryfan, in the Ogwen/ Nant Ffrancon valley and on Elidir Fawr. Deposits, where present, are quite extensive. Example crags are:
Carnedd Y Filiast (Cairn of the Greyhound Bitch) (Wrongly listed as Rhyolite)
Carreg Mianog
There's even more in Central Wales. It's found in the Rhinogydd (extensive deposits; almost every crag here is a gritstone crag) as well as on the coast south of Aberystwyth, north of Pumlumon and in the Elan Valley. Example crags are:
Carreg yr Ogof
Craig y Merched
Craig yr Eglwys
Ynys Lochtyn
Craig Cnwch
Rhinogydd grit in particular is very variable in nature, some crags being composed of stuff which is very coarse indeed, c/w gravel clasts. Unlike Peak grit, incut holds are commonplace. It's lovely stuff to climb.
> 'Gritstone' is a very English thing.
Hmmm ...... that's a bit of an anglo-centric viewpoint!
There's gritstone in both North Wales and Central Wales. Geologically, most of it is older than Peak/ Pennine grit and lithologically it's on a continuum, locally varying from being a coarse sandstone to a medium coarse grit.
In North Wales it's found on Tryfan, in the Ogwen/ Nant Ffrancon valley and on Elidir Fawr. Deposits, where present, are quite extensive. Example crags are:
Carnedd Y Filiast (Cairn of the Greyhound Bitch) (Wrongly listed as Rhyolite)
Carreg Mianog
There's even more in Central Wales. It's found in the Rhinogydd (extensive deposits; almost every crag here is a gritstone crag) as well as on the coast south of Aberystwyth, north of Pumlumon and in the Elan Valley. Example crags are:
Carreg yr Ogof
Craig y Merched
Craig yr Eglwys
Ynys Lochtyn
Craig Cnwch
Rhinogydd grit in particular is very variable in nature, some crags being composed of stuff which is very coarse indeed, c/w gravel clasts. Unlike Peak grit, incut holds are commonplace. It's lovely stuff to climb.
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In reply to wbo:
Hard to say given that most of it has been dug up. Although as I've implied, I may well be wrong about what actually constitues a gritstone!
> where does that leave Millstone then?
Hard to say given that most of it has been dug up. Although as I've implied, I may well be wrong about what actually constitues a gritstone!
In reply to Dave Williams:
I though a lot of Welsh 'grit' rocks were actually greywhakes which were formed by a different method,
Chris
I though a lot of Welsh 'grit' rocks were actually greywhakes which were formed by a different method,
Chris
In reply to ianstevens:
I thought the key feature of millstone grit is actually the cement, which makes the rock so durable. It is silica (redeposited quartz) in grits rather than the softer (and usually redder) iron carbonates etc for 'normal' sandstone,
Chris
> I was under the impression that the key feature of a gritstone in contrast to a sandstone is that it also has some larger clasts that are gravel sized, not just sand-sized clasts. When I stated coarse sand, I meant just that - it's actually a very precise technical term in sedimentology and sedimentary geology. Gravel clasts aren't present in all of the Welsh "Grit" that I've experinced.
I thought the key feature of millstone grit is actually the cement, which makes the rock so durable. It is silica (redeposited quartz) in grits rather than the softer (and usually redder) iron carbonates etc for 'normal' sandstone,
Chris
In reply to ianstevens:
Coarse to very coarse sandstone, with or without gravel conglomerate or other clasts.
> I may well be wrong about what actually constitues a gritstone!
Coarse to very coarse sandstone, with or without gravel conglomerate or other clasts.
Post edited at 15:19
In reply to ianstevens:
Yes indeed. In geological terms 'sand' specifically refers to particles between 0.063mm and 2mm across, which are further sub-divided into fine/medium/coarse. Gravel is anything between 2.0 - 63mm, again sub-divided f/m/c.
The Millstone Grit Series are fine to coarse sandstones, but vary a lot in terms of specific proportions of different grain sizes, including gravel sized particles etc.
I think the sand particles are generally fairly angular too, which is probably why the friction is so good (maybe due to fairly quick process of erosion from parent rock and deposition when it was first formed).
The Grit that outcrops in Wales is essentially the same in terms of geological classification as the stuff in the Pennines. It was all formed at the same time, in similar depositional environments, and from same parent rock, although the stuff in Midlands was probably formed in a different basin than that in Wales.
So geologically its all the same. But from a climbing point of view there are no doubt better and worse examples due to variability of its make up.
> I was under the impression that the key feature of a gritstone in contrast to a sandstone is that it also has some larger clasts that are gravel sized, not just sand-sized clasts. When I stated coarse sand, I meant just that - it's actually a very precise technical term in sedimentology and sedimentary geology. Gravel clasts aren't present in all of the Welsh "Grit" that I've experinced.
Yes indeed. In geological terms 'sand' specifically refers to particles between 0.063mm and 2mm across, which are further sub-divided into fine/medium/coarse. Gravel is anything between 2.0 - 63mm, again sub-divided f/m/c.
The Millstone Grit Series are fine to coarse sandstones, but vary a lot in terms of specific proportions of different grain sizes, including gravel sized particles etc.
I think the sand particles are generally fairly angular too, which is probably why the friction is so good (maybe due to fairly quick process of erosion from parent rock and deposition when it was first formed).
The Grit that outcrops in Wales is essentially the same in terms of geological classification as the stuff in the Pennines. It was all formed at the same time, in similar depositional environments, and from same parent rock, although the stuff in Midlands was probably formed in a different basin than that in Wales.
So geologically its all the same. But from a climbing point of view there are no doubt better and worse examples due to variability of its make up.
In reply to Chris Craggs:
Yes, this is correct for Central Wales' deposits.
Gritstone is a descriptive term for a hard, medium to coarse-grained, silica-rich sedimentary sandstone, mainly composed of feldspar, mica and quartz minerals. The dominance of one (or more) minerals over others can give rise to different types of gritstone - eg. quartz gritstones (Rhinogydd); feldspathic gritstones (Peak).
Most gritstones are formed under water where the mode of origin can vary from deltaic (Pennine), to beach (Elidir series); to deep sea basin turbidites/ greywakes (Rhinog).
Some exposures of gritstone are incredibly uniform and compact and free from lines of weakness. This is true of all gritstones, irrespective of origin. This uniform compactness leads to bold, runnerless climbing, a feature common to both Peak and Welsh grit.
In other places, both Welsh and Peak grit contains strata that is weaker and therefore far more susceptible to weathering which, over time, forms horizontal and vertical indentations which may then grow ever deeper to form breaks and later cracks. Some of the grit on the Rhinogydd is cracked to such an extent that it is literally crevasse-like in form.
HTH
Dave
> I though a lot of Welsh 'grit' rocks were actually greywhakes which were formed by a different method,
Yes, this is correct for Central Wales' deposits.
Gritstone is a descriptive term for a hard, medium to coarse-grained, silica-rich sedimentary sandstone, mainly composed of feldspar, mica and quartz minerals. The dominance of one (or more) minerals over others can give rise to different types of gritstone - eg. quartz gritstones (Rhinogydd); feldspathic gritstones (Peak).
Most gritstones are formed under water where the mode of origin can vary from deltaic (Pennine), to beach (Elidir series); to deep sea basin turbidites/ greywakes (Rhinog).
Some exposures of gritstone are incredibly uniform and compact and free from lines of weakness. This is true of all gritstones, irrespective of origin. This uniform compactness leads to bold, runnerless climbing, a feature common to both Peak and Welsh grit.
In other places, both Welsh and Peak grit contains strata that is weaker and therefore far more susceptible to weathering which, over time, forms horizontal and vertical indentations which may then grow ever deeper to form breaks and later cracks. Some of the grit on the Rhinogydd is cracked to such an extent that it is literally crevasse-like in form.
HTH
Dave
Post edited at 16:08
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In reply to Chris Craggs:
Having spent an entire afternoon researching what a gritstone is, thinking that everything I know about sedimentology was wrong, even contacting fellow sedimentologists, professors etc.
I couldn't find a single published/formal definition for what constitutes a gritstone (despite its use in many articles). I finally settled on the BGS glossary definition which is, low and behold, 'a coarse grained sandstone'. It's simply an informal synonym.
It's an old term, probably local to the north of England, that has somehow survived into literature. In pure geology though there is no such rock type as a gritstone. Nor does the term gritstone feature as part of any formal classification for siliciclastic rocks, certainly not in any modern and internationally regarded scheme. Phil79's post covers the grainsize classification well.
Having spent an entire afternoon researching what a gritstone is, thinking that everything I know about sedimentology was wrong, even contacting fellow sedimentologists, professors etc.
I couldn't find a single published/formal definition for what constitutes a gritstone (despite its use in many articles). I finally settled on the BGS glossary definition which is, low and behold, 'a coarse grained sandstone'. It's simply an informal synonym.
It's an old term, probably local to the north of England, that has somehow survived into literature. In pure geology though there is no such rock type as a gritstone. Nor does the term gritstone feature as part of any formal classification for siliciclastic rocks, certainly not in any modern and internationally regarded scheme. Phil79's post covers the grainsize classification well.
In reply to GarethSL:
'Gritstone' is simply a shorthand name for 'Millstone Grit', the particular hard sandstone of Carboniferous Age that's found in the English Peak District and Yorkshire. It's a regional term, rather than a rock type (as you say) - though it's characteristics are very specific (e.g. it has very strong 'cement' - as Chris Craggs says – so that its interior is as strong as the surface i.e. completely unlike many sandstones, particularly South-East Sandstone).
'Gritstone' is simply a shorthand name for 'Millstone Grit', the particular hard sandstone of Carboniferous Age that's found in the English Peak District and Yorkshire. It's a regional term, rather than a rock type (as you say) - though it's characteristics are very specific (e.g. it has very strong 'cement' - as Chris Craggs says – so that its interior is as strong as the surface i.e. completely unlike many sandstones, particularly South-East Sandstone).
Post edited at 16:38
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In reply to GarethSL:
Yep, I think you're right. Grit isn't a formal geological term that I'm aware of.
The whole geological sequence has historically been called 'Millstone Grit', and is now termed the Millstone Grit Group by the BGS, but as with many geological series/sequence names, it has just adopted the archaic local term for the rock type.
http://www.bgs.ac.uk/Lexicon/lexicon.cfm?pub=MG
The BGS will probably rename it with something terminally bland eventually, as they have with other things (Keuper Marl comes to mind).
TBH I forgotten 90% of the sedimentology/geology I was taught, its all rather rusty.
> I couldn't find a single published/formal definition for what constitutes a gritstone (despite its use in many articles). I finally settled on the BGS glossary definition which is, low and behold, 'a coarse grained sandstone'. It's simply an informal synonym.
Yep, I think you're right. Grit isn't a formal geological term that I'm aware of.
The whole geological sequence has historically been called 'Millstone Grit', and is now termed the Millstone Grit Group by the BGS, but as with many geological series/sequence names, it has just adopted the archaic local term for the rock type.
http://www.bgs.ac.uk/Lexicon/lexicon.cfm?pub=MG
The BGS will probably rename it with something terminally bland eventually, as they have with other things (Keuper Marl comes to mind).
TBH I forgotten 90% of the sedimentology/geology I was taught, its all rather rusty.
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In reply to Phil79:
In think the stuff we all know at gritstone (all previous comments about there being no such thing accepted) the grains are actually quite rounded as are the the occasional bigger pebbles due to it being a delta deposit and the material having been carried quite far. This also explains the lack of other minerals, as there were winnowed out or dissolved.
....where as these are rapidly buried sediments (subduction zone?) indicated by the angular grains and mixture of minerals.
Chris
> I think the sand particles are generally fairly angular too, which is probably why the friction is so good (maybe due to fairly quick process of erosion from parent rock and deposition when it was first formed).
In think the stuff we all know at gritstone (all previous comments about there being no such thing accepted) the grains are actually quite rounded as are the the occasional bigger pebbles due to it being a delta deposit and the material having been carried quite far. This also explains the lack of other minerals, as there were winnowed out or dissolved.
> The Grit that outcrops in Wales is essentially the same in terms of geological classification as the stuff in the Pennines. It was all formed at the same time, in similar depositional environments, and from same parent rock, although the stuff in Midlands was probably formed in a different basin than that in Wales.
....where as these are rapidly buried sediments (subduction zone?) indicated by the angular grains and mixture of minerals.
Chris
Post edited at 17:16
In reply to Chris Craggs: no, for me the greater angularity of the dirtier greywacke sediments just implies a shorter travel distance, decreased sorting of the sediments.
In reply to Gordon Stainforth:
The interior of Millstone Grit is absolutely not as strong as the surface as like all sandstones the surface usually chemically hardens in contact with the elements; its just stronger than other sandstones.
The interior of Millstone Grit is absolutely not as strong as the surface as like all sandstones the surface usually chemically hardens in contact with the elements; its just stronger than other sandstones.
In reply to wbo:
This should get thread of the year, thanks for all the discussion guys, very interesting.
This should get thread of the year, thanks for all the discussion guys, very interesting.
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In reply to Toccata:
Toccata, sorry for offtopic...I found your reply about carribean bouldering in older post:
"I found some stunning limestone (I think, it was a long time ago) on Tobago. A horizontal roof 2 meters off the sandy beach about 4 meters in depth and 50m long/wide. The holds were pretty decent and problems from V0-8, mainly V4-6. And there was a bar just above it!"
Do you remember where it is?
Toccata, sorry for offtopic...I found your reply about carribean bouldering in older post:
"I found some stunning limestone (I think, it was a long time ago) on Tobago. A horizontal roof 2 meters off the sandy beach about 4 meters in depth and 50m long/wide. The holds were pretty decent and problems from V0-8, mainly V4-6. And there was a bar just above it!"
Do you remember where it is?
In reply to Pkrynicki1984:
Derbyshire in the main, with a few minor off cuts in South Yorkshire and Staffordshire. Coughs and gets coat!
Derbyshire in the main, with a few minor off cuts in South Yorkshire and Staffordshire. Coughs and gets coat!
In reply to Pkrynicki1984:
While the geological definitions are extremely interesting, surely from a climbers perspective the question still stands. Where else in the world do you get rock that feels and climbs like our grit?
I've been interested in this question for many years and still haven't seen any convincing evidence that grit climbing exists outside of the UK, and I've looked a lot on the internet! The best candidates I know of are a few outcrops in Australia where routes were climbed in headpoint style (old OTE mag has a short piece), some coarse sandstone in northen france, and that's about it. There is a lot of granite on the web that looks teasingly like weathered grit (with breaks and cracks) but certainly won't climb like it...
While the geological definitions are extremely interesting, surely from a climbers perspective the question still stands. Where else in the world do you get rock that feels and climbs like our grit?
I've been interested in this question for many years and still haven't seen any convincing evidence that grit climbing exists outside of the UK, and I've looked a lot on the internet! The best candidates I know of are a few outcrops in Australia where routes were climbed in headpoint style (old OTE mag has a short piece), some coarse sandstone in northen france, and that's about it. There is a lot of granite on the web that looks teasingly like weathered grit (with breaks and cracks) but certainly won't climb like it...
In reply to Offwidth:
Well, absolutely, yes. But, relatively, it is remarkably strong, otherwise a millstone, once cut to shape, wouldn't have worked as a millstone. It would have lasted no time at all.
> The interior of Millstone Grit is absolutely not as strong as the surface as like all sandstones the surface usually chemically hardens in contact with the elements; its just stronger than other sandstones.
Well, absolutely, yes. But, relatively, it is remarkably strong, otherwise a millstone, once cut to shape, wouldn't have worked as a millstone. It would have lasted no time at all.
In reply to Gordon Stainforth:
Pennsylvania has been suggested, but it looks much like sandstone to me. Andy Popp is out there currently exploring, will ask him to comment.
Pennsylvania has been suggested, but it looks much like sandstone to me. Andy Popp is out there currently exploring, will ask him to comment.
In reply to Jon Read:
I think the rock in SW Pennsylvania/ West Virginia is very gritstone like, same Carboniferous age and similarly associated with coal deposits. I spent an afternoon at Coopers Rocks many years ago, it felt very much like one of the finer grained gritstones (more Roaches than Stanage). A friendly bunch of unemployed coal miners showed me around, to complete the similarity with the Peak in the 1980s.
I think the rock in SW Pennsylvania/ West Virginia is very gritstone like, same Carboniferous age and similarly associated with coal deposits. I spent an afternoon at Coopers Rocks many years ago, it felt very much like one of the finer grained gritstones (more Roaches than Stanage). A friendly bunch of unemployed coal miners showed me around, to complete the similarity with the Peak in the 1980s.
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In reply to dr_botnik:
Only if you're a grit cretin does this topic excite.
> This should get thread of the year, thanks for all the discussion guys, very interesting.
Only if you're a grit cretin does this topic excite.
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In reply to Uncle_Kris:
Yes. At the southern end of Store bay, underneath the Crown Point Hotel. Low tide only and you can see the rock/roof in this photo. That's a bar just above it! I left some great projects...
http://l7.alamy.com/zooms/c6396bfa9b0e4ba7b51280f23fbba004/store-beach-on-s...
> Toccata, sorry for offtopic...I found your reply about carribean bouldering in older post:
> "I found some stunning limestone (I think, it was a long time ago) on Tobago. A horizontal roof 2 meters off the sandy beach about 4 meters in depth and 50m long/wide. The holds were pretty decent and problems from V0-8, mainly V4-6. And there was a bar just above it!"
> Do you remember where it is?
Yes. At the southern end of Store bay, underneath the Crown Point Hotel. Low tide only and you can see the rock/roof in this photo. That's a bar just above it! I left some great projects...
http://l7.alamy.com/zooms/c6396bfa9b0e4ba7b51280f23fbba004/store-beach-on-s...
In reply to Jon Read:
I think what you need to look for is somewhere with a similar sandstone (it's hardly unique), combined with a long history of being exposed to a piddling rain to get the surface recemented just so. That rules out stuff like the Dakota FM in the US - it's great for bouldering, but it's just too dry (go look at Eldorado Canyon, Red Rocks, for examples of great sst climbing )
The Pfalz - ? I'll have a think of some more.
To Zimpara - I'm sorry this bores you but I'm sure you can find a nice thread on rope soloing grade III's somewhere. Hows your sweaty underwear?
I think what you need to look for is somewhere with a similar sandstone (it's hardly unique), combined with a long history of being exposed to a piddling rain to get the surface recemented just so. That rules out stuff like the Dakota FM in the US - it's great for bouldering, but it's just too dry (go look at Eldorado Canyon, Red Rocks, for examples of great sst climbing )
The Pfalz - ? I'll have a think of some more.
To Zimpara - I'm sorry this bores you but I'm sure you can find a nice thread on rope soloing grade III's somewhere. Hows your sweaty underwear?
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In reply to Jon Read:
Comments so far, from the other channel:
'Lovely conditions on (Pennsylvania) grit this morning ... '
'It claims to be grit. And certainly has some grit like qualities.'
> Pennsylvania has been suggested, but it looks much like sandstone to me. Andy Popp is out there currently exploring, will ask him to comment.
Comments so far, from the other channel:
'Lovely conditions on (Pennsylvania) grit this morning ... '
'It claims to be grit. And certainly has some grit like qualities.'
In reply to dr_botnik:
+1 to this. civil, informative debate. ukc at its best.
> This should get thread of the year, thanks for all the discussion guys, very interesting.
+1 to this. civil, informative debate. ukc at its best.
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In reply to Adam Long:
We also have: "My local spot (ten minutes from home) is meant to be grit ... but I'm not convinced."
The Popp jury is out!
We also have: "My local spot (ten minutes from home) is meant to be grit ... but I'm not convinced."
The Popp jury is out!
In reply to Pkrynicki1984:
I wish Dartmoor Granite was more skin friendly like Grit. My hands get trashed every week it seems! It's the Feldspar that causes the damage!
I wish Dartmoor Granite was more skin friendly like Grit. My hands get trashed every week it seems! It's the Feldspar that causes the damage!
In reply to Pkrynicki1984:
In the absence of Deepstar and PK could I mention Mendip millstone grit as featured on Gilson's Slab . Now is the time to get down and do a bit of gardening before it disappears again.
In the absence of Deepstar and PK could I mention Mendip millstone grit as featured on Gilson's Slab . Now is the time to get down and do a bit of gardening before it disappears again.
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In reply to Pkrynicki1984:
Extract from Rusty Peg on 03 Feb 2010 in forums:
"The chunky gritstone walls of Yes Tor and Little Hangman are just brilliant. "
Extract from Rusty Peg on 03 Feb 2010 in forums:
"The chunky gritstone walls of Yes Tor and Little Hangman are just brilliant. "
In reply to Pkrynicki1984:
Lancashire of course.
You know about the Peak and Yorkshire but not Lancashire?
> Where in the world does Gritstone occur?
> I know you get it in the Peak , Yorkshire , Northumberland , Ireland and even North Spain.... where else?
Lancashire of course.
You know about the Peak and Yorkshire but not Lancashire?
In reply to Chris Craggs:
No one seems to have picked up on this point. The main difference between the Peak and Northumberland isn't the clast size..
Edit: Have just seen Gordon's post.
> I thought the key feature of millstone grit is actually the cement, which makes the rock so durable. It is silica (redeposited quartz) in grits rather than the softer (and usually redder) iron carbonates etc for 'normal' sandstone,
> Chris
No one seems to have picked up on this point. The main difference between the Peak and Northumberland isn't the clast size..
Edit: Have just seen Gordon's post.
Post edited at 08:49
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In reply to zimpara:
Whereas the common or garden cretin reads (possibly) then *responds to* a thread in which he has no interest.
> Only if you're a grit cretin does this topic excite.
Whereas the common or garden cretin reads (possibly) then *responds to* a thread in which he has no interest.
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