Lieut.-Colonel Sykes on a portion of Dukhun, 429 



the parallels of latitude 16° and l?** N., bear testimony to the trap extending- 

 nearly a degree and a half further south along the Ghats than Mr. Calder 

 supposed. Indeed its southern limit in the Konkun_, Mr. Eraser states to be 

 at Malwan^ fifty miles north of Goa*. Prom the above evidence we have proofs 

 of a continuous trap formation covering an area of from 200^000 to 250,000 

 square miles, a phsBnomenon unexampled in any other country whose geolo- 

 gical structure has been examined. It appears to me, however, that the above 

 are not the absolute limits of the trap. Dr. Buchanan f and Mr. Jones J 

 describe the Rajmahl hills in latitude 25° and longitude 88° to 89° E. as 

 trap ; the latter says the basalt is of amazing thickness. The Rev. Mr. Everest§, 

 in a journey from Calcutta to Ghazipoor, passed four distinct broad beds of 

 trap between the parallels of north latitude 23° and 24°, and longitude 84° 

 and 87°. He states these beds to have an inclination to a common axis, and 

 he thinks it probable they are connected beneath the granite and gneiss. 

 Mr. Royle travelling the same route, observed the same beds. Mr. Everest's 

 diagram shows their longitudinal axis on a line between the Rajmahl hills and 

 the sources of the Nerbuddeh and Soan rivers ; and as the trap of the Vindhya 

 range and Sagar extends towards these sources, it is very probable the rami- 

 fications are connected with the beds (seen by Mr. Everest) and the Rajmahl 

 hills, forming a belt across India from the 73° to the 89° of longitude, ex- 

 tending, in fact, from near the mouth of the Nerbuddeh river to the Ganges 

 at Rajmahl. The southern limit of trap is much lower than is assigned to it 

 by Mr. Calder, as Dr. Voysey describes a basaltic dyke at Seringapatam, in 

 latitude 12° 26'; and Mr. Calder himself mentions partial deposits of over- 

 lying rocks as far south as Cotallum, at the extremity of the great western 

 range, between the parallels of latitude 8° and 9°. Mr. Babington, passing- 

 through Mysore, describes all the black rocks he met with as hornblende pass- 

 ing into basalt. He evidently adverts also to nodular basalty. 



Jge of Trap. 



With respect to the age of the great trap formation of India, it would ap- 

 pear from Major Franklin's Memoir on Bundelkund, that its northern ex- 

 tremities rest on sandstone, which he considers identical with the new red 

 sandstone of England ; the trap would therefore be posterior to the carboni- 

 ferous series and belong to the supermedial order. But the Rev. Mr. Everestf 

 adduces valid reasons for questioning the correctness of Major Franklin's 

 opinion ; and it may be inferred, that he is doubtful with respect to the exact 



* Geol. Trans., 2nd Series, part i. p. 153. t Gleanings of Science, vol. iii. Jan., 1831, p. 1. 



X Phys. Class, As. Researches, p. 165. § Gleanings of Science, vol. iii. p. 135. 



II Geol. Trans., 1st Series, vol. v. p. 225. % Gleanings of Science, vol. iii. p. 211. 



3 K 2 



