Valley of Oodipoor. 275 



that rain-water possesses the property of dissolving the linnestone 

 rocks over which it flows. To this source many of the recent 

 calc tuffs are traceable ; and the same cause operating at a for- 

 mer period, and for an indefinite length of time, may very pro- 

 bably have given birth to some of our kunkur deposits. 



The kunkur, considered as a formation, seems referable to 

 an era posterior to that which gave birth to our newer marine 

 deposits, but many causes may liave simultaneously contributed 

 to the production of calcareous beds, variously modified, ac- 

 cording to the sites upon which they were deposited, the phe- 

 nomena attending their deposition, and the nature of the causes 

 concerned. Hence we may have lacustrine kunkurs, and 

 kunkurs traceable to the solvent properties of rain and river 

 water, of cotemporaneous formation, with others of a very dif- 

 ferent origin. 



From the extensive distribution of the kunkur formation, 

 from the uniformity in the composition of the cementing medium, 

 the chemical portion of this deposit, and from the great simila- 

 rity in point of texture and appearance between the kunkurs of 

 remote localities, we may infer that one cause at least, of a very 

 general and uniform character, operated in its production. But, 

 while we attribute to this one distinct cause the principal share 

 in the deposition of kunkur, considered as a widely distributed 

 formation, we must at the same time allow that local causes 

 may, in many instances, have modified the character and ap- 

 pearance of the rock itself, or ^ven birth . to cotemporaneous^ 

 beds of calcareous substances, in many respects analogous to the 

 others. Beds, too, of this last description, may have been form- 

 ed at various periods, and many extensive geological changes 

 may have taken place in the subjacent strata, during the aera 

 which gave origin to the kunkur formation, considered on the 

 great scale. 



In making geological inductions, it is a good general rule to 

 inquire, in the first place, whether or not any of the causes still 

 in active operation on the surface of our globe are, on the sup- 

 position of their having been equally active at a remote period, 

 sufficient in themselves to explain the phenomena which happen 

 to engage our attention. If we come to the conclusion that 

 such causes do exist, we need not look for others of a more oc- 



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