Aynho weir lock.

One of the curiosities of the canals, this very shallow, only about a foot deep, lozenge shaped lock was built to stop the River Cherwell flowing down the canal, as the next lock is Somerton, about 12 ft deep, the shallow lock needed to pass enough enough water to supply the deep one, hence the shape giving a greater volume.

The River Cherwell crosses just above the lock, it flows in from the right and out under the arches to the left.