While the design of different parts of the palisade varied greatly, and changed with time, the palisades, according to the research of the modern geographer R.L. Edmonds, typically consisted of two parallel earthen levees 3 "chi" (just over 1 meter) high and wide, separated by a trench that was about 1 "zhang" (3.5 m) deep and 1 "zhang" wide. Rows of willow trees were planted on top of the levees, each tree's branches being tied to those of its neighbors. Certain sections of the palisades system coincided with the old (Ming dynasty) Liaodong Wall - the extension of the Great Wall of China meant to protect the Ming Liaoning from the Manchus - and there no willows needed to be planted.