MEMOIRS 



OF THE 



GEOLOGICAL SORVEY OF INDIA. 



On the TEAPS and intertrappban beds of Western and Central India, hy 

 William T. Blanford, Assoc. Eoy, School of Mines, f. g. s., Sj-c, 

 Deputy Superintendent, Geol. Survey of India. 



CONTENTS. 



1. — Introduction, Previous Observers. 

 2. — Area covered by traps. 

 3. — Petrology. 



4. — Occurrence of volcanic ash. 

 5. — Horizontality of traps. Thickness of beds. 

 6 — Volcanic foci. 



7. — The Deccan and Malwa traps not of sub- 

 marine origin. 



8. — Duration of volcanic period. 

 9. — Intertrappean beds. 

 10. — Distinctions between intertrappeans of 

 Bombay and those of Central India. 

 11. — Theories of formation of the inter- 

 trappean beds. 

 12 — Geological age of Deccan and Malwa 

 traps. 



1. Introduction. — During the five years which have now elapsed 

 since the Geological Survey of India was extended to the Bombay 

 Presidency, a very considerable portion of the immense tract occupied by 

 volcanic rocks in Western and Central India has been examined, more or 

 less closely. Nearly the whole valley of the Taptee and its tributaries, 

 the Nerbuddda valley west of Hoshungabad, and a considerable tract of 

 country around Nagpoor, have been surveyed ; whilst rapid traverses of 

 the country between Bombay and Nagpoor have been made, and the 

 neighbourhoods of Bombay, Poena, Ahmednuggur, Jaulna, Mahablesh- 

 war, Baitool, Chindwarra, and Rajamundry, together with portions of 

 Sind and of Cutch, have been more or less closely examined. 



Until however still more extensive areas of this widely spread series 

 of rocks have been surveyed, no complete general account of them can 

 Memoirs of the Geological Survey of India, Vol. VI, Art, 5, 



( 137 ) 



