The tectonic scene

DYNAMIC HIMALAYA: K. S. Valdiya; Universities Press (India) Ltd., 3-5-819, Hyderguda, Hyderabad-500029. Rs. 160.

THIS EDUCATIONAL monograph seeks to provide basic information on the evolutionary process before the emergence of the giant edifice, Himalaya. In the context of the recent Gujarat earthquake the book gains in significance by explaining the collision and welding of India with Asia. India, according to the text, collided with mainland Asia about 65 million years ago and such a collision caused a multiplicity of deep and steep faults.

The breaking up of the ancient Gondwanaland - comprising what are presently the continents of Antarctica, Australia, India, Africa and South America - was preceded and accompanied by bursts of volcanism, as explained in the chapter ``Era of growing tectonic instability''.

In this context the picture caption of the unique ice stalagmite of tremendous beatitude in the holy cave of Amarnath says it is located in the 230 million-year-old late Triassic limestone of the Zanskar Range.

The well researched book relates the several crusted upheavals of great severity in the Himalaya, young in age, but complex in its structural design. This is well referred to in the preface by the author who records: ``Crustal movements not only squeezed the rock piles into folds and overlapping sheets but also tore them apart and uprooted them from the original sites of the formation''. Besides narrating the whole process of Himalayan formation, the author also points out the several beauties that the ranges have conferred on India - as controller of climate, forestry and biodiversity, energy from hot springs and on top of it all, the mighty rivers.

On earthquake activity, the author says, that the region is geodynamically very active, prone to violent crustal movements. It also carries a warning that the ecosystem is very fragile and often vulnerable to even small disturbances. The explosive growth of population pushing up the demand for fuel wood and timber results in dwindling forests. Several species of plants and animals, according to the author are facing the risk of elimination by the drastic modification of the habitats.

As examples he cites the snow leopard, fishing cat and lynx and among the endangered birds are the bearded vulture, horned pheasant and mountain quail. The drying of springs becoming seasonal in the lesser Himalayan terrain is termed as the most alarming development.

The book is well illustrated with sketches, maps, colour photographs which is certain to meet the objective mentioned by the author, viz. ``to portray a simplified picture of the setting and origin of the Himalaya.''

With more than three decades of his study of the geological profile of the Himalaya, the book, mainly intended for students, can well be of great interest to laymen.

As he points out in the chapter ``Continuing tectonic unrest'' his observation that ``the region is in a strongly stressed state and the build up of strains is manifest in the movements that have taken place and are taking place on the many east-west faults'' is topically relevant in the context of the recent Gujarat disaster.

The book is published in collaboration with the Jawaharlal Nehru Centre for Advanced Scientific Research.

SVK

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