Click any picture to enlarge it.
It is a lone sarsen in a field - as far as I know nothing is known about it. But obviously it has been recognised as having some significance as it hasn't been dragged to the field edge.
Reminds me a bit of the Cuckoo stone, Torstone and Heel stone...
More details at:
The Hanging Stone (Wiltshire) Standing Stone (Menhir) : The Megalithic Portal and Megalith Map:: "Site Name: The Hanging Stone (Wiltshire)
Country: England County: Wiltshire Type: Standing Stone (Menhir)
Nearest Town: Devizes Nearest Village: Woodborough
Map Ref: SU099605 Landranger Map Number: 173
Latitude: 51.343500N Longitude: 1.859252W"
Looks like a glacial erratic?ReplyDelete
Looks like but probably not. There are a lot of other sarsens in the area, even in the edges of the same field.ReplyDelete
The Pewsey Vale dissolved out of Chalk. The sarsens were on the top of the chalk and got left behind once the chalk had gone.
How did the Sarsen get into the chalk?
Chalk is the remains of marine animals that died in the sea and floated to the bottom and sandstone is sand at the bottom - so if the chalk was eroded, would it not just leave a bedrock of sandstone?
For Sandstone to turn into rocks it must have been exposed to weathering (for a long time) then the sea had to cover the land and then chalk to form - so we must have a scenario of Sea with sand falling to the bottom causing sandstone, then sea gone with weathering to make rocks, followed by more sea with animals this time making chalk and rocks contained within - the back to land again?
I didn't think these rocks are that old?
Sarsens form on top of the chalk so they are not that old. They come from sand and gravel bars in shallow water over a chalk base. As the water goes down acidic swamps form over the sand. Silification then binds the grains together. We can see the root holes of the vegetation growing above the forming stones. The unsilified sands and gravels erode away and leave the hard kernals of stone on top of the exposed chalk. If the chalk then erodes away the stones are left in the resultant soil.Delete
Ok thanks for that info.ReplyDelete
Why are the ones found all around the south coasts are so small while Avebury and Stonehenge stone so large in comparison?
And how long would it take to erode the chalk above theses stones and what method - ice or water?
Here's a handy description from Bill Nye the science guyDelete
I'm not a geologist but I believe it is water erosion, dissolving, helped by freezing and thawing to open up cracks but not physical erosion by ice.ReplyDelete
As to the sizes and composition - sarsens include puddingstones which are made of fist size pebbles as well as the fine sand ones of the Marlborough Downs that can only be put down to the variations in the sandbeds in which they formed.