Stonehenge and its Environs 134
Image by RiotGibbon
Stonehenge and its Environs

Satellite imagery

On second thoughts, the altitude seems too high to have been part of the Avon, maybe you've discovered something new :-)

-Chris

Chris Collyer wrote:
....maybe you've discovered something new :-)

-Chris

Unfortunately, its highly unlikely.

It'd be as big as Durrington Walls with round barrows within {if circular} and doesn't appear on Google Earth:
http://maps.google.co.uk/maps?ll=51.190223,-1.8084287&z=16&t=h&hl=en