地图图形往往具有一定程度的空间结构特征，例如树枝状水系、棋盘状街道网等。
There are many structural units on maps , such as dendriform drainage and orthogonal streets .
树枝状水系型式的发展是由遭受侵蚀的岩石类型和层态影响的。
Development of the dendritic pattern is influenced by the type and attitude of rock the erosion encounters .
树枝状水系树枝状水系树枝状水系