STRATIGRAPHICAL FEATURES. 15 



CHAPTER III.-STRATIGRAPHICAL FEATURES. 



(CRYSTALLINE ROCKS.) 



With the exception of the schists and quartzites of the Aravalli 

 system, which are only found along the eastern border of the area 

 under discussion, and are everywhere vertical or highly inclined to 

 the horizon, the rocks met with have suffered very little disturbance 

 since they were first formed, a circumstance which adds considerably 

 to the difficulty of working out their relations with each other, for 

 many of the isolated exposures exhibit only one variety of rock, 

 entirely cut off from all visible contact with those that may be asso- 

 ciated with it, by the surrounding sand. As before mentioned, nearly 

 the whole of the rocks seen are crystalline, and can only be distin- 

 guished from each other on petrological and stratigraphical grounds. 

 The only fossiliferous rocks in the whole of Marwar are the sandstones 

 of Barmer, and the age of these even is a matter of doubt, since the 

 fossils, which almost without exception are plant remains, are in so 

 fragmentary a condition that it is difficult to form any definite conclu- 

 sions from them. 



It is impossible in the present state of our knowledge of the crys- 

 talline formations of India to identify the crystalline rocks of Marwar 

 with those of other localities, and just as the region is sharply cut 

 off by its climate and aspect from the remainder of India, so the 

 geology must be regarded for the present as peculiar to this area. In 

 fact, the most widespread formation that occurs here, the volcanic 

 lavas and tuffs of the Malani series, are so far as is yet known,, con- 

 fined strictly to this part of the country, and have no representatives 

 in other parts of India. 



The formations represented are given in. the following table, the 



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