Question 16ElaborateGS1GS1

Post-drift theories based on ocean floor mapping provided new dimensions to the study of distribution of oceans and continents. Elaborate.

Introduction

Continental Drift Theory for Wegener explained how continents had shifted apart from Pangea but failed to explain the cause of such drift.

22 words

Main Body

Post drift theories aimed to explain the cause as well as the features of ocean floor and continent. (1) Convectional Current Theory by Holmes:- The theory explains the mechanism of continental movement through convection cells in the Earth's interior, showing rising limbs of magma and descending limbs.

Ring magma from mantle formed convection cells. Rising limbsdivergence. Descend limbconvergence. (2) Sea Floor Spreading theory by Hess (Sidwell):- mid-oceanic ridges like shallow earthquakes with basaltic vulcanoes; trenches had deep focused earthquakes; sea rocks equidistant from MOR had similar characteristics; Ocean floor had younger strata continental. It showed that new floor was created at MOR due to diverging limbs and the same floor had consumed at trenches.

3Plate Tectonic Theory:- The lithosphere is divided into several tectonic belts that float overwhelmingly. These are continuously moving & hence it lead to several types of interactions. eg: Continental - Oceanic Convergence. There, subduction led to relief features such as volcanoes, fold mountain etc. Thus post drift theories provided us much our current understanding of cause & type of oceanic & continental features.

182 words1 paragraphs

Conclusion

Post drift theories provided us with our current understanding of cause and type of oceanic and continental features.

18 words

Diagram

Convection cells showing surface, rising limbs of magma, descending limbs, and core

Clear progression from weak theory to strong post-drift theories
Includes diagram for visual understanding
Mentions specific scientific mechanism

Open original scan

Page 38

Topper

Hrishikesh Alare

AIR 612022

Subject & Paper

GS1GS1

Topic

Salient features of World's Physical Geography

Distribution of Key Natural Resources and Geological Features

Plate Tectonics and Continental Drift

Writing Stats

222

Total words

Paragraphs