Geology n' rocks n' stuff

#61
Good thread!
The one big regret I have in life...is not following a boyhood passion for paleantology but that's another story.

The massive boulders & chunks of rock you see on the moorlands going up the A9 are, I'm told, "rubble" ripped out by glaciers, and will not have moved since the melt. Incredible.
Known as "erratics"
 
#62
Oooh is that a hint of a concordial fracture i see there
Yes, but made by the thing on the left. 'Conchoidal'. Its not a spearpoint.
Here's a few conchoidal fractures on a core I found in the Saudi desert:
1.jpg

2.jpg

Made to produce flakes for spear/arrow/whatever. That came from
25°41'55.8"N 46°22'20.3"E. Flint, of which there's none in the area that I know of. Most of the interesting rock there is quite a bit older, and produces all sorts of Cretaceous sea fossils.

PS Saudi is fantastic for fossil-hunting; I have shelves of sea-fans, sand dollars, shark's teeth etc from the areas to the NE of Riyadh and off the road to Hofuf. In any rocky part of the country it can all be picked up without digging. Finding man-made tools is a little more rare, and the core above was a real surprise.

Edited for extreme myopia.
 
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#63
Would these be the same as "conchoidal" fractures?

As seen on my rather impressive lump of obsidian...


OK. How do I put a photo on here?
 
#64
I'll blame the tablet for the spelling and that its about a minute behind on the keystrokes.
Volcanic glass is the goto example for conchoidal fractures which would mean we are in harmony or concordial.
 
#66
Good thread!
The one big regret I have in life...is not following a boyhood passion for paleantology but that's another story.
It all kicked off form camping holidays in Lyme Regis..so you can guess.
This reminds me of digging out down about 5 feet in a back garden when we lived in an old house in Falkirk, quite near the Roman Antonine Wall in the 80's. It was easy enough as the soil was very sandy & was full of pebbles...and there is the clue.
I ended up with buckets of variuos shells which I wrongly thought would have been a Roman skip, but they turned out to be much older when I called in a local historian. She was certain that back in pre-Neolithic times, the Forth's banks were there and even beyond our house. It looked like I'd stumbled across an ancient rubbish tip. There were other artifacts which she removed, but I never pursued the outcomes...was just too busy draining the swamp which was the "garden".
I wish I'd followed it up.
The massive boulders & chunks of rock you see on the moorlands going up the A9 are, I'm told, "rubble" ripped out by glaciers, and will not have moved since the melt. Incredible.



My bold, there's an interesting rock in the middle of a minor road in a village near me, called the "Soulberry Boot".. The Soulbury stone never loses – and now the council knows it

snip "This week, Buckinghamshire county council became the latest to realise that one tangles with the low, unprepossessing boulder, somewhat eccentrically situated in the middle of the tarmacked surface of Chapel Hill, at one’s peril.
By Thursday, once the stone had featured on national TV and radio, this particular immovable object had, true to form, overcome the council’s highly resistible force. “We completely understand the significance of the stone to villagers,” said Mark Shaw, the council’s cabinet member for transportation, “and will do all that we can to make any appropriate safety changes to the area around the stone, but not move the stone itself. Clearly the stone is the true heart and soul of Soulbury.”
Why such a fight for this small boulder? Soulbury’s stone (never “rock”, notes Wright’s wife, June, who made that mistake – once – while taking the parish council minutes) does not even have any archaeological value. It was placed at the junction of Chapel Hill and High Road, notes Mike Palmer, keeper of natural history at Bucks County Museum, not by neolithic humans marking a burial spot or a significant ford, but by an ice age glacier, which transported the chunk of 300-million-year-old carboniferous limestone from much further north – probably the Peak District – some 450,000 years ago."


This is the stone, in the middle of a junction...

 
#68
My bold, there's an interesting rock in the middle of a minor road in a village near me, called the "Soulberry Boot".. The Soulbury stone never loses – and now the council knows it

snip "This week, Buckinghamshire county council became the latest to realise that one tangles with the low, unprepossessing boulder, somewhat eccentrically situated in the middle of the tarmacked surface of Chapel Hill, at one’s peril.
By Thursday, once the stone had featured on national TV and radio, this particular immovable object had, true to form, overcome the council’s highly resistible force. “We completely understand the significance of the stone to villagers,” said Mark Shaw, the council’s cabinet member for transportation, “and will do all that we can to make any appropriate safety changes to the area around the stone, but not move the stone itself. Clearly the stone is the true heart and soul of Soulbury.”
Why such a fight for this small boulder? Soulbury’s stone (never “rock”, notes Wright’s wife, June, who made that mistake – once – while taking the parish council minutes) does not even have any archaeological value. It was placed at the junction of Chapel Hill and High Road, notes Mike Palmer, keeper of natural history at Bucks County Museum, not by neolithic humans marking a burial spot or a significant ford, but by an ice age glacier, which transported the chunk of 300-million-year-old carboniferous limestone from much further north – probably the Peak District – some 450,000 years ago."


This is the stone, in the middle of a junction...

450,000 years? 11,000 - 15,000 is more likely.
 
#73
That bit raised my brows as well. Busy multi-tasking at the moment..yes...honest...so I'll check it out laters.



Well the report was from that ever so pc organ of truth, so beloved by our resident SJW's, whose veracity can never be doubted...... unless one has a brain & thinks for oneself :)
However Wiki does define "glacial erratics" thus In the 19th century, many scientists came to favor erratics as evidence for the end of the Last Glacial Maximum (ice age) approx. 10,000 years ago.
So more like the usual p**s poor "lefty" journalism.
 
#74
I got a book from Amazon called Reading the Irish Landscape. This geology lark is rather complicated. Turns out that the massive ice caps that formed on the mountains of Scotland fed glaciers that invaded Ireland. Granite from Ailsa Craig in the Firth of Clyde has been found in Cork Harbour.
 
#75
Granite from Ailsa Craig in the Firth of Clyde has been found in Cork Harbour.
True. If you scour the pebble beaches of the East of Ireland you'll find all sorts of stuff from further North. I don't have any Ailsa Craig granite on my windowsills, but because the geological history of this part of the world is so complex, do have other granites, gneisses, metamorphic and sedimentary rock which must have travelled hundreds of miles. I'm fairly close to one of the very few spots in NI where there's a good crop of large, usable flint, too (54.477810, -6.218594) so when I used to do a bit of knapping that's where I got the material. The other spot for flint is on the Antrim coast, on the site which Time Team got all excited over a few years ago (Knockdhu).
 
#78
Apparently, there was a glacial period around 400k years ago. The stone could be from then.
It’s possible, but you would have to suspect that an erratic of that age would be well buried in the surface clays that are typical in that area. After a quick google I’ve found references to it being both 11,000 years and 450,000 years but no information as to how these ages were determined.
 
#79
It’s possible, but you would have to suspect that an erratic of that age would be well buried in the surface clays that are typical in that area. After a quick google I’ve found references to it being both 11,000 years and 450,000 years but no information as to how these ages were determined.
There have been loads of ice ages.

They are not easy to date and many dating methods take geology well beyond hitting a rock with a hammer and into the realm of advanced physics.

Good overview here: Dating Glacial Sediments
 
#80
There have been loads of ice ages.

They are not easy to date and many dating methods take geology well beyond hitting a rock with a hammer and into the realm of advanced physics.

Good overview here: Dating Glacial Sediments
Perhaps I didn’t express myself very well. None of the articles referring to the particular glacial period which resulted in the deposition of the Soulbury erratic explained what dating method had been used.
 

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