Monday, June 3, 2013

Going Hiking In Pangaean India

I have been thinking unhappy thoughts ever since I came upon this map of Pangaea with today's political boundaries overlaid on it.

Where would I have going hiking in Pangaean India?

1) The Himalayas, crown jewel of hikers arose begining early Cenozoic and reached their bewitching heights in the mid Miocene -Pliocene.

2) The Western Ghats, the poor man's Himalayas, arose in the Cenozoic too after the breakup of India from Madagascar (88 mya) and Seychelles (66 mya). They represent heights reached due to an initial high rift flank, amplified by denudational isostacy and crustal upwarp due to intraplate stresses propagated southwards from the Himalayan collisional zone.

3) The Eastern Ghats, a line of mountains parallel to the east coast of India also arose much later than Pangaea forming during and after the breakup of India with Antarctica about 130 mya.

4) The Vindhyan and Satpura mountains in central India are composed of Proterozoic and late Paleozoic -Mesozoic rocks resp. but much of today's relief also represents topography rejuvenated since mid Cenozoic, ultimately related to stresses from the Himalayan collision.

5) The Aravalli mountains in Rajasthan is a Proterozoic orogenic belt but probably didn't have much topography during Pangaean times.

For most of the time period from Cambrian to Carboniferous the Indian shield was a tectonically stable area. Pangaean India was a place where a vast peneplain had developed over most of the Indian shield in response to long lasting denudation. This cycle of deep weathering and erosion lasting tens to a hundred million years would have stripped and ultimately flattened the Aravalli and south Indian orogenic mountains, exposing mountain roots and lower crustal rocks like granulites and charnokites. The result would have been a subdued topography with a flat horizon as far as the eye can see, occasionally interrupted by gentle rolling hillocks made up of more resistant lithologies like quartzites and charnokites. 

Subsequent episodes of uplift and erosion has destroyed this flat topographic surface from all over the Indian peninsular region but some remnants of this peneplain termed the Gondwana surface can be observed at around 2400 m mantling the granulites of south India around the popular hill stations of Ooty and Kodaikanal in the Nilgiri mountains.  It has been lifted to these heights during Cenozoic uplift of the Western Ghats.

The only places of considerable relief would have been the emerging Permo-Triassic rift basins of the Satpura, Pranhita Godavari and Mahanadi belts in the central and eastern part of  country. A horst graben structure would have resulting in a ridge and flat valley type topography. Not particularly attractive for a challenging hike. Plus it was really swampy and hot in those rift basins.

I wouldn't have liked to live in Pangaean India. I am too spoilt by views like this one, which appeared only in the Miocene.

Photo: Nanda Devi and Namik Glacier in the Kumaon Himalayas, November 2012.


  1. It would have been fun hiking in Antartica
    God knows what secrets it hides below its ice today

  2. Antarctica has significant Precambrian terrain... so schists, gneiss, granulites and also Gondwana rift basins like eastern India. :) so Pangaean Antarctica may have been similar to India over large areas.. flattish topography!

  3. The photo and the pose remind of the famous Mallory quote

    "Because it's there"