INTRODUCTION. 11 



Classified List of Formations in Extra-Peninsular Territories belonging to 



India. — contd. 

 (H. B. Medlicott and W. T. Elanford, 1879) — contd. 

 Permian and Car- Salt Range Carboniferous limestone. Damudas of Sikkim and 

 bom'ferous. Bhutan '? Infra-triassic of Hazara ? Kiol limestone of 



Pir Panjal ? Krol limestone and Infra-Ki'ol of Western 

 Himalayas ? Killing series of North-Western Himalayas 

 and Kashmir. Maulmain group of Burma. 

 Silurian l . . Obolus beds of Salt Range. Attock slates of Upper Punjab ? 

 Slates and traps of Pir Panjal and Kashmir ? Muth and 

 Bhabeh series of North-Western Himalayas. Blaini and 

 Infra-Blaini of Simla ai'ea ? 

 Infra-Silurian . Salt marl of Salt Range ? Gneiss of Pir Panjal and Ladak. 

 Upper gneiss of Zanskar range. Shillong series of Assam 

 lulls ? Mergui group ? 

 Lower or central gneiss of Himalayas. Gneiss of Assam and 

 Burma. 

 Those formations about which at the time there appeared to be reasonable 

 doubt as to their positions in the list are marked with a note of interrogation. 

 1 Silurian is here used in its old sense as including the Ordovician and Cambrian. 



The second edition of the official Manual, prepared by Mr. 

 R. D. Oldham and issued in 1893, showed the progress which had 

 been made during the next fourteen years in extending the survey 

 over new ground, and in adding precision to the correlation of 

 the isolated outcrops of Indian formations with one . another and 

 with the European scale. In consequence of this progress in 

 knowledge it was found possible to make a much more complete 

 grouping of isolated formations in chronological order instead of 

 maintaining the geographical divisions, although possibly some of 

 the groupings were undertaken prematurely. 



The new edition of the Manual introduced greater precision in 

 the treatment of nearly every division of the rocks, the progress 

 of knowledge and removal of difficulties being shown by the reduc- 

 tion in the bulk of the work. The small number of changes made 

 in classification, however, showed that the work of the Survey 

 as organised by Dr. T. Oldham had proceeded on sound scientific 

 lines. Among the " Metamorphic and Crystalline rocks " the old 

 division into the granitoid gneisses of Bundelkhand and the 

 schistose and banded forms of Bengal was maintained by 

 R. D. Oldham and extended to other parts of India. At the 

 time the igneous nature of the granitoid types was only just 

 beginning to be appreciated. The old division into Lower and 

 Upper Transitions was abandoned in favour of regarding the 

 foliated and seinHoliated schistose forms to be " Transitions," such 



