Prehistoric Engineering

I found this a few weeks ago in the beck almost certainly from the Stainton gravel beds , I believe it could be a man made counter balance or anchor I found the piece in the beck so am almost sure it is related to the Stainton gravel beds dating between 12 - 17 tybp

 The gap is almost identical all the way around , the centre is circular and I believe the piece was used to whined a twine of some sort . 

 The rock also appears to have been shaped for some reason . This piece again ime sure is from the Stainton gravel beds dating 12 - 17000 ybp .

The two pieces below were found at an earlier date in the same stretch of water and appear to be made of the same sandstone .