October 16, 1914] 



SCIENCE 



539 



can Trap occurred there was a continual 

 unloading of Gondwanaland, and a con- 

 tinual consequent overloading of the ocean 

 bed immediately to the north; that this 

 process went on with a gradual rise on one 

 side and a gradual depression on the other ; 

 and that somewhere near and parallel to 

 the boundary line the crust must have been 

 undergoing stresses which resulted in 

 strain, and, as I suggest, the development 

 of those fissures that let loose the floods of 

 Deccan Trap and brought to an end the 

 delicate isostatic balance. 



During the secular subsidence of the 

 northex-n shore line of Gondwanaland, ac- 

 companied by the slow accumulation of 

 sediment near the shore and the gradual 

 filing away of the land above sea-level, 

 there must have been a gradual creep of 

 the crust in a northerly direction. Near 

 the west end of the Himalayan are this 

 movement would be towards the northwest 

 for a part of the time ; at the east end the 

 creep would be towards the north-north- 

 east and northeast. Thus there would be a 

 tendency from well back in Paleozoic times 

 up to the end of the Cretaceous period for 

 normal faults — faults of tension — ^to de- 

 velop on the land, with a trend varying 

 from W.S.W.-E.N.E. to W.N.W.-E.S.E. 

 across the northern part of Gondwanaland. 

 We know nothing of the evidence now 

 pigeon-holed below the great mantle of 

 Gangetic alluvium, while the records of 

 the Himalayan region have been masked 

 or destroyed by later foldings. But in the 

 stratified rocks lying just south of the 

 southern margin of the great alluvial belt 

 we find a common tendency for faults to 

 strike in this way across the present penin- 

 sula of India. These faults have, for in- 

 stance, marked out the great belt of coal- 

 fields stretching for some 200 miles from 

 east to west in the Damuda valley. On 

 this, the east side of India, the fractures 



of tension have a general trend of W.N.W.- 

 E.S.E. We know that these faults are 

 later than the Permian period, but some of 

 them certainly were not much later. 



If now we go westwards across the Cen- 

 tral Provinces and Central India and into 

 the eastern part of the Bombay Presidency, 

 we find records of this kind still more 

 strikingly preserved ; for where the Gond- 

 wana rocks, ranging from Permo-Carbon- 

 iferous to Liassic in age, rest on the much 

 older Vindhyan series, we find three main 

 series of these faults. One series was de- 

 veloped before Permo-Carboniferous times ; 

 another traverses the lower Gondwanas, 

 which range up to about the end of Per- 

 mian times ; while the third set affects the 

 younger and Upper Gondwanas of about 

 Rhsetic or Liassic age. Although the pres- 

 ent topography of the country follows 

 closely the outlines of the geological forma- 

 tions, it is clear from the work of the Geo- 

 logical Survey of India that these outlines 

 were determined in Mesozoic times, and 

 that the movements which formed the latest 

 series of faults were but continuations of 

 those which manifested themselves in Pale- 

 ozoic times. According to Mr. J. G. Med- 

 lieott, the field data showed "that a tend- 

 ency to yield in general east and west or 

 more clearly northeast and southwest lines 

 existed in this great area from the remote 

 period of the Vindhyan fault. "^^ The 

 author of the memoir and map on this 

 area was certainly not suspicious of the 

 ideas of which I am now unburdening my 

 mind; on the contrary, he attempted and, 

 with apologies, failed to reconcile his facts 

 to views then being pushed by the weight 

 of "authority" in Europe. This was not 

 the last time that facts established in India 

 were found (to use a field-geologist's term) 

 unconformably to lie on a basement of 



"Mem. Geol. Surv. Ind., Vol. II., 1860, Part 

 2, p. 256. 



