Geological Pics - Post any interesting photo here

53989108420_4e5f325c8e_k.jpgso this is a photo I took last summer in an old quarry near Mylor Creek in Cornwall, I have been wondering for some time as to what it maybe.
I don’t know if it’s obvious, but it’s a mineral vein running over base rocks.
I suppose the obvious question is, why were they quarrying here? Were they looking for this mineral or was it that they wanted the rock and we’re discarding the minerals?
If it’s any help the grid ref of the quarry is: SW 812 357
 
Yorkshire Lad said:
View attachment 1643so this is a photo I took last summer in an old quarry near Mylor Creek in Cornwall, I have been wondering for some time as to what it maybe.
I don’t know if it’s obvious, but it’s a mineral vein running over base rocks.
I suppose the obvious question is, why were they quarrying here? Were they looking for this mineral or was it that they wanted the rock and we’re discarding the minerals?
If it’s any help the grid ref of the quarry is: SW 812 357
Click to expand...
Have you checked on the BGS website ?
 
The quarry is in the Porthleven Breccia Member of Devonian Age. God knows what they'd be quarrying from that. I'm not convinced that's a vein per se, but it certainly looks like a bit of a crush zone or fault. We need someone with a bit more rock info on this one!
 
BertyBasset said:
The quarry is in the Porthleven Breccia Member of Devonian Age. God knows what they'd be quarrying from that. I'm not convinced that's a vein per se, but it certainly looks like a bit of a crush zone or fault. We need someone with a bit more rock info on this one!
Click to expand...
Here’s another photo from the same location, again strange geological occurrence 53988994869_91184488f9_k.jpg
 
Yorkshire Lad said:
If you like unconformity you should visit my home town of Knaresborough where on my daily commute I cycle past Addlethorpe Grit, a Carboniferous Sedimentary Sandstone 322 million years old over lain by Dolostone of the Cadeby Formation, a Permian Sedimentary Siltstone 272 million years old old. Somewhere there are 50 million years of rocks missing!
Click to expand...
Yep know that one well. I grew up in Harrogate and Knaresborough was where i started to get interested in proper geology walkiing along the gorge with parents on a Sunday outing. The Cadeby Formation is Yorkshire is one of my private research topics looking at the associated mineralisation within the Formation.
 
Alex said:
View attachment 1899

Some folds in a coal mine. Could something like this have happened after the Coal had been taken?
Click to expand...
Just folded as part of the roof fall deforming the soft shales. Disseminated Pyrite in the shales chemically reacts in contact with air and water producing Ferrous Sulphate , a mineral called Melanterite which are the brown areas. The process also forms sulphuric acid which reacts with any calcium carbonate in the shales to produce gypsum - the white mineral on the right hand side of the photo. The disruption of expansive minerals forming weakens the roof layers and they peel off.
 
Yorkshire Lad said:
If you like unconformity you should visit my home town of Knaresborough where on my daily commute I cycle past Addlethorpe Grit, a Carboniferous Sedimentary Sandstone 322 million years old over lain by Dolostone of the Cadeby Formation, a Permian Sedimentary Siltstone 272 million years old old. Somewhere there are 50 million years of rocks missing!
Click to expand...
I thought it was just me 🤣 at Easter I was in Knaresborough, performing the touristic tedium of over busy main car park, tea and slice of cake in Riverside cafe, then up steps to the castle -- all the time wishing I was doing something more worthwhile and subterranean. However Mrs cantclimbtom and accompanying friends are very much cake not cave. Anyhow... I got told off for overly admiring the rocks by the river and up to castle not noticing the boats etc. Didn't get chance to look that closely but there's some variety there, not all of one type. Immediately obvious that it's somewhere interesting geologically
 
cantclimbtom said:
I thought it was just me 🤣 at Easter I was in Knaresborough, performing the touristic tedium of over busy main car park, tea and slice of cake in Riverside cafe, then up steps to the castle -- all the time wishing I was doing something more worthwhile and subterranean. However Mrs cantclimbtom and accompanying friends are very much cake not cave. Anyhow... I got told off for overly admiring the rocks by the river and up to castle not noticing the boats etc. Didn't get chance to look that closely but there's some variety there, not all of one type. Immediately obvious that it's somewhere interesting geologically
Click to expand...
Not only are the rock interesting at Knaresborough, but further up the gorge, are the remains of Medieval Coal Mines along Bilton Banks, and just before you get to Ripley some old limestone quarries.
 
Yorkshire Lad said:
Not only are the rock interesting at Knaresborough, but further up the gorge, are the remains of Medieval Coal Mines along Bilton Banks, and just before you get to Ripley some old limestone quarries.
Click to expand...
Yep remember visiting them. Then there is the cave at Old Mother Shiptons with the petrified items sitting in the spring flow.
 
mudstone nenthead area.jpg
I was recently privileged to see some amazing layered sediments in a mine level in the Alston Moor area - I was entrusted to be discrete about location. But this is amazing - trying to imagine the processes that created this is difficult! I am pretty sure this is not ground movement - I think this is the mudstone, or whatever, as exposed in the level.
 
Nice. That seems to show several cyclical episodes of deposition, deformation and erosion. It's presumably deltaic and some of the layering might be cross bedding as opposed to 'true' beds. There's definitely deformation - that white 'marker' layer's been almost overturned at the top - and that's before to 'top' layer's been deposited.
 
You must log in or register to reply here.
Back