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Difficulty: MediumDrainage Patterns and River Basin Analysis

A topographical map extract shows a series of streams radiating outward from a central dome, with subsequent tributaries capturing flow along concentric ring valleys formed on eroded sedimentary layers. Which drainage pattern is illustrated by this stream arrangement?

  1. Annular patternAnswer
  2. B
    Radial pattern
  3. C
    Centripetal pattern
  4. D
    Trellis pattern

Answer

Annular drainage pattern
Annular drainage develops on maturely dissected domes where alternating concentric bands of hard and soft rock are exposed. Main streams flow outward from the dome, while tributary streams carve circular, ring-like channels along the softer rock belts.

Step-by-Step Solution

1
Analyze the structural landform and elevation description in the stem.
Identified a dissected dome structure with elevated center and concentric belts of contrasting rock hardness.
Geological structure dictates the structural control governing drainage network development.
2
Evaluate stream geometry and flow direction.
Streams flow outwards from the high central region, while tributary streams follow curved concentric bands of weaker rock.
Differential erosion creates circular valleys where tributaries flow along rings around the central dome.
3
Match the observed stream geometry to standard genetic drainage patterns.
The ring-like or circular pattern around a central upland is classified as annular drainage.
Annular pattern is defined by concentric ring-like stream paths formed on breached domes or maturely dissected structural domes.

Key Concept

Annular Drainage Pattern and Structural Controls
Estimated Time:1m 15s
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Topics

Drainage Patterns and River Basin Analysis

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