The sketch map shows the main dam, which was solid and rose to a height above normal high water level.

The flash lock was in the centre, with a winch on the north bank to haul the barges through against the current.

Near to the island was a "tumbling bay", an overfall weir with its crest just below normal low water level.

One would have expanded the mill stream on the Whitchurch side, and another would have involved a cut across land occupied by the Swan public house at Pangbourne.

In the later 19th century local people used to cross over the weir to avoid paying tolls on the bridge.

The hills on the Oxfordshire side are populated by houses at Whitchurch and are then covered by the Hartslock beech woods.

These were built by D. H. Evans the shop owner and were nicknamed the "Seven Deadly Sins" as it was alleged that he kept a mistress in each of them.