Monkey Marsh Lock
A Scheduled Ancient Monument, and one of only two surviving turf-sided locks. This early lock design was most often used on river navigations in the early 1700s before the advent of canals. The sides of the turf-lock are sloping so, when full, the lock is quite wide.
Consequently, this type of lock needs more water to operate than the now more common brick or stone-sided variety. Most of the locks of this type on the River Kennet were rebuilt with brick sides - and just this and Garston Lock at Theale remain in turf. Garston is the more authentic of the two.