AP

ANKITA PATILAIR 140· 2025

Question Q.15Discuss the concept of isostasy and explain its role in shaping Earth's major landforms.GS1GS1

DISCUSS the concept of isostasy and explain its role in shaping Earth's major landforms. (15 marks, 250 words)

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AnswerStrengthsGapsKeywords

Introduction

The phenomenon of isostasy is defined as the maintainance of equilibrium in the earth's lithosphere in relation to the various underlying geological forces experienced in all crustal, mantle layers of the earth.

32 words

Main Body

Definition and basic concept:

Isostasy refers to the maintenance of equilibrium in the Earth's lithosphere, controlled by the interaction of various underlying geological forces across crustal and mantle layers.

Factors Impacting Isostasy:

1The maintenance of equilibrium is affected by the maintaining force experienced in [the lithosphere]

Factors impacting isostasy (continued):

2Tectonic movements along constructive and destructive boundaries impact isostasy
3Volcanism witnessed as a result of rising magma alters the lithospheric topography

ROLE IN SHAPING EARTH'S LANDFORMS

(I) Mountains Formation:

1Fold mountains formed at convergent boundaries are a result of isostasy
2The subducting plate compensates for the rising plate [isostatic principle]

[Diagram showing convergent boundary interaction between plates]

(II) Rift Valleys and Block Mountains:

1Rift diastrophism witnessed in the block mountains
2For the rising block mountain [isostatic adjustment occurs]

Valley formation (continued):

Rift Valleys:

1Rift valleys are result of vertical forces on the blocks along fault lines
2Rifts have consequent deep valley formation in ocean topography too
3Sea floor spreading contributes to mid-oceanic ridge and trenches - maintains isostasy
4Divergent boundaries → Trenches undersea

Volcanic Landforms:

1The mantle plumes lead to formation of volcanic arcs and islands

[Diagram showing Black Mountains with Horst and Graben formation]

Repetition of previous section (pages 34-35 appear identical):

Valley formation:

1The rift valleys are result of vertical forces on the blocks along fault lines
2The rifts have consequent deep valley in ocean topography too
3Sea floor spreading contributes to mid-oceanic ridge and trenches maintaining isostasy
4Divergent boundaries → Trenches undersea

Volcanic Landforms:

1The mantle plumes lead to formation of volcanic arcs and islands
275 words17 paragraphs

Conclusion

The phenomenon of isostasy is crucial to study the topography, landforms of the earth showing a socio-economic impact on resident population as well.

23 words

Diagram

Cross-section diagram of Earth's layers labeled: Lithosphere, Mountain, Crust, Asthenosphere, Mantle, Outer liquid core, Inner solid core - showing internal structure relevant to isostatic processes

  • Good definition provided
  • Relevant diagram included
  • Establishes multi-layer perspective

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Page 32

Topper

ANKITA PATIL

AIR 1402025

Subject & Paper

GS1GS1

Topic

Salient features of World's Physical Geography

Important Geophysical Phenomena

Isostasy and landform development

Writing Stats

330

Total words

17

Paragraphs