This line extends down the short slope of a notch in a ridge, then up the other side to a slightly higher point immediately above a small valley lacking canals.

• 山脊上有个小坎，圆石列一路排下小坎的短坡，再延伸到小坎另一侧稍高处，那里可俯瞰一个小山谷，谷里正缺水。