Identifying Drainage Patterns Unrelated to Structure

A drainage pattern describes how a river and its tributaries are arranged over a landscape. Many patterns are directly influenced by the underlying geological structure (like rock type, faults, and folds).

Drainage Patterns Related to Structure

• Radial drainage: Rivers flow outwards from a central high point (like a dome or volcano). This pattern is related to the structural uplift.
• Trellis drainage: Forms in areas with folded strata or resistant ridges. Rivers flow along valleys parallel to folds, with tributaries joining at right angles. This is highly dependent on geological structure.
• Dendritic drainage: Resembles tree branches. It typically forms on uniform rock structures where the river follows the path of least resistance without significant structural control dictating its exact course, but it develops *in response* to the uniformity of the structure.

Drainage Patterns Not Related to Structure

Superimposed drainage (also called antecedent drainage) is a pattern that originates on an overlying rock layer or structure but continues its course *across* a newly exposed, underlying structure that would normally dictate a different pattern. The drainage pattern essentially cuts through the underlying structure, meaning it is inherited and not controlled by the current geological structure it traverses.

Therefore, a drainage pattern not related to the existing structure of the region is superimposed drainage.

Final Answer

The correct option is Superimposed drainage.