Original sentence: It is estimated that the site began to fall out of use around 3000BC, about the same time as the  earliest earthworks at Stonehenge (itself originally a causewayed enclosure) began.It was probably constructed at some time around 4000BC and in use possibly up to 3000BC
Edited sentence: It is estimated that the site began to fall out of use around 3000 BC, about the same time as the  earliest earthworks at Stonehenge (itself originally a causewayed enclosure) began.It was probably constructed at some time around 4000 BC and in use possibly up to 3000 BC