Question

Difficulty: MediumDrainage Patterns and River Basin Analysis

Match each specified drainage pattern with its underlying geological control or characteristic landform surface.

  • Trellis drainage patternForms in folded strata with alternating parallel belts of hard and soft rock layers.
  • Rectangular drainage patternDevelops along faulted, jointed, or fractured bedrock, causing streams to make sharp right-angled bends.
  • Radial drainage patternFlows outward away from a central elevated high point, such as a volcanic cone or isolated dome.
  • Dendritic drainage patternResembles the branching structure of a tree, forming on rocks with uniform resistance to erosion.

Answer

Trellis drainage pattern matches with folded strata containing alternating hard and soft rocks; Rectangular pattern matches with faulted and jointed bedrock; Radial pattern matches with outward flow from a central dome or volcano; Dendritic pattern matches with tree-like branching on uniform rock resistance.
Each pattern corresponds directly to its bedrock control: Trellis requires alternating soft/hard folded belts, Rectangular follows structural joints and faults, Radial descends from a central highland dome or cone, and Dendritic branches randomly over uniform lithology.

Step-by-Step Solution

1
Analyze Trellis Drainage Pattern
Trellis drainage features long main streams parallel to strike valleys with short tributaries entering at right angles, characteristic of folded, tilted strata.
Differential erosion along parallel belts of soft and hard rock forces tributaries into strike valleys.
2
Analyze Rectangular Drainage Pattern
Rectangular drainage is characterized by right-angled bends in main streams and tributaries along lineaments.
Bedrock fractures, joint systems, and faults direct the line of weakest resistance for stream incision.
3
Analyze Radial Drainage Pattern
Radial drainage streams flow in all cardinal directions downward from a central peak.
Topographic highs like domes and volcanic summits direct water outward along radial slopes.
4
Analyze Dendritic Drainage Pattern
Dendritic drainage exhibits a random branching tree-like structure without structural alignment.
Uniform rock resistance (lithology) allows equal erosion in all directions.

Key Concept

Geological Controls on Drainage Network Patterns
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