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Friday, 22 May 2015

Rhosyfelin -- how heavy is the big stone?


Can somebody please assist in some calculations?  Prof MPP says in his book that the Rhosyfelin "proto-orthostat" -- so greatly revered that some even take off their wellies to stand on it -- is about 13 feet long and weighs about 4 tonnes, i.e as much as the large bluestones at Stonehenge.

I measured it today, and found that it is c 3.80 m long, c 1.30 m wide and .60 m deep.  That gives a volume of 2.964 m3.  Multiply by 2.7 for rhyolite, and that gives a weight of just over 8 tonnes.

Has anybody done an "official" calculation?  If so, what is the "official weight"?  Myris, what do your geological friends say?

Many of us who have examined it are quite sure it is far too big and heavy to be a candidate for hauling off to Stonehenge -- quite apart from its lack of structural integrity, of which more anon......

In my estimation, if any attempt was to be made to move it away from this site, it would break in half in pretty short order.  "Ah yes", will say the archaeologists, "that's why the heroic Neolithic tribesmen  left it behind, following its rejection by the project engineer."

15 comments:

Evergreen said...

Burl has 2.5-2.6 for Rhyolite, 159lbs per cubic foot. Not that that changes things greatly.

Myris of Alexandria said...

Most of the bluestones are thought to be closer to two tonnes in weight.
A specific gravity of 2.7 is perfectly reasonable, these are siliciclastics rocks.
M

BRIAN JOHN said...

So around 8 tonnes it is -- twice the weight as assumed by Prof MPP. Surely this dumps the "proto-orthostat" idea once and for all?

Phil Morgan said...

Is it the pre-dressed weight perhaps, or the original Altar Stone?

BRIAN JOHN said...

Interesting -- 34 page views on this one already..... a lot of people seem to be interested!

Evergreen said...

It's v interesting indeed Brian and well done for checking. The answer would seem to be either Mike needs a new calculator or this must be one of the famous hollow bluestones of Rhosyfelin.

Being at the end of the 'rails', 15m from the Quarry face (sorry), if it wasn't a ready-to-go stone, could it perhaps have served a different purpose?

And a totally innocent question - If it wasn't moved by people, what would be your best guess as to how it got where it was found? What, if anything, did you make of the 'rails'?

BRIAN JOHN said...

The rails? as I have saiud before, I see no rails -- all I see under the stone is a random selection of rubble and blocks, some of which have chunks knocked off them and also fractures, probably attributable to the massive impact when the rock fell. It must have come down with quite a crash. I exhumed it the other day from that black shroud, and it is a seriously interesting rock. Watch this space....

BRIAN JOHN said...

Evergreen -- the big stone is not 15 m from the rock face. One end is 4m from the rock face, and the other end is 5.7m from the rock face. Goodness knows where that 15m came from!!

And it's not at the end of any "rails" -- as you can see in all the pics, there are one or two elongated stones underneath the big stone, but they are not parallel with one another or with the elongated sides of the stone. They are just broken stones, randomly arranged -- the "rails" are a complete figment of the MPP imagination.

BRIAN JOHN said...

I checked the dimensions again today, and my measurements are still 3.80 x 1.30 x 0.60. So the weight is still 8 tonnes, and we continue to wonder how the archaeologists could have got it so wrong.

Evergreen said...

Hi Brian, this is why I asked earlier on another post if something is being overlooked. The stone isnt the weight quoted by MPP, isn't in the same place and the rails are nowhere to be found..

I have to ask, and it sounds ridiculous, but - Is it the same stone Mike is referring to?!

BRIAN JOHN said...

No doubt about it, Evergreen. This is the very stone that has had all the celebrity treatment -- no doubt Myris will confirm.

Evergreen said...

Then I don't know what to suggest is going on here. Very strange indeed.

Evergreen said...

Just read the bit in MPPs book again. He actually says "It lies at the end of what appear to be three parallel 'rails' of stones set on edge, leading to that part of the outcrop about 15 metres away from which it has been detached. "

chris johnson said...

I can confirm that the Altar Stone or Picnic Table or That Which All The Fuss Is About is where Brian says it is. The only way both Brian and MPP can be right is when MPP has removed the rails and provenanced the rock to a place further uphill, some 15 metres uphill.

BRIAN JOHN said...

I'm intrigued that nobody is coming up with any evidence that the stone weighs c 4 tonnes. So are we all now agreed that 8 tonnes is now approx the right weight?