Harold st george grey found no evidence of silting or water in the bottom of the ditch when he excavated circa 1908.
The wells within Avebury are very deep now (Look down the well in the Keiller room in the red lion)
If the ditch was Cleaned every year then there would have been evidence of silting after it was abandoned and started to fill up.
Burl reckons that the winterbourne was not there when the beckhampton avenue was built but I find this hard to comprehend.
The depth of the ditch was astonishing. Some of the chalk was used as packing for the stones of the outer circle making the ditch earlier than the outer part of the circle.
Looking at Norths' work recently I am thinking now in terms of astronomical observation from the bottom of the ditch.
Wotcha reckon?