INTRODUCTION. 7 



Devonian ?. — The salt marl of the Salt Range was considered 

 to be probably Devonian on account of the observation of Dr. 

 Fleming that it occurred under the Carboniferous (Productus) Lime- 

 stone. 



Silurian. — A brief reference is made to the occurrence of Silurian 

 trilobites and other fossils in the Central Himalaya. 



It will be noticed that, while Greenough's notes, by including 

 the discoveries of Strachey and Fleming, showed a material advance 

 on previous summaries, the classification of Indian formations was 

 still in a primitive state, marked by great deficiencies and striking 

 errors in correlation. 



A more serious attempt to unravel the problems of Indian 

 geologv was made with the employment in 1851 of the distinguished 

 geologist, Dr. T. Oldham. For the first few years of his service 

 Dr. Oldham was occupied on areas supposed to contain valuable 

 deposits of coal and iron ; but. in spite of the fact that his work 

 was intended to be more directly economic, he was able in 1856 to 

 reduce his observations to order, and in that year the regular Geologial 

 Survey was organised, the first part of the now well-known Memoirs 

 was issued, and Dr. Oldham was able to lay the foundation of 

 a stratigraphical classification. With the year 1856, therefore, a new 

 era in the history of Indian geological research was commenced. 



It was at the May meeting of the Asiatic Society of Bengal 1 

 in 1856 that Dr. Oldham made his first contribution to the classi- 

 fication and nomenclature of Indian geological formations. He there 

 proposed to adopt the name Vindhyan for the great group of un- 

 fossiliferous strata stretching across the northern part of the 

 Peninsula, sub-dividing the group into : — 



3. Bundair. 

 2. Rewah. 

 1. Kyrnore. 



He recognised the fact that the Vindhyan formations were older 

 than the threat coal-bearing group of sandstones and shales, which 

 for the time being he regarded as Jurassic in age and distin- 

 guished by the name Damoodah. The sandstone formations of 

 the Pachmarhi hills he regarded as younger than the Damoodahs 



1 Journal Asiatic Society of Bengal, Vol. XXV, pp. 240—254, 1856. 



