12 THAPS AND INTERTRAPPEAN BED« 



measured. Yet that long intervals of time, in some cases, at least, 

 elapsed between the different lava flows of which this immense thickness 

 is composed, is shown by the local accumulation of freshwater deposits 

 abounding in remains of animals and plants.* In each of these cases 

 a lake must have been formed, and have become tenanted by a 

 large number of different species of mollusca, &c., a very slow pro- 

 cess. In some places, near Baroda, I met with large accumulations of 

 rounded pebbles, not only of metamorphic and sedimentary rocks, but of 

 the trap itself, intercalated between beds of basalt and amygdaloid, so 

 that denudation must have taken place to a considerable extent in the 

 intervals between successive floWs.t These accumulations appeared to 

 have been deposited in hollows excavated in the underlying trap beds, 

 and as currents of water must have been necessary to move such pebbles 

 and to round them, it is only reasonable to conclude that these hollows 

 were river beds, cut into the surface of the consolidated trap flows, and 

 refilled by gravel and detritus, all in the interval between successive 

 feruptions. It should, however, be added that these signs of long inter- 

 vals are confined, so far as I have as yet observed them, to traps very 

 low down in the series. 



9. — Intertrappean beds, — I have already had occasion to advert to 

 the sedimentary beds intercalated with the traps. These have been 

 described by various writers, but especially by Dr. MalcolmsonJ, Dr. 

 Carter§, Mr. HislopU, and Mr. J. G. Medlicott*i[. The first described 



* I shall show presently that these were accumulated in intervals between trap flows, 

 and not, as held by Mr. Hisolp and Dr. Cartel', previously to the commencement of the 

 volcanic outbursts. 



t This has been observed by Mr. J. G. Medlicott also ; Memoirs of Geological Survey 

 of India, Vol. II, p. 208. 



X Geol, Trans., Ser. 2, Vol. V, p. 549, &c. 



§ Jour. Bombay Br. Roy. As. Soc, Vol. IV, p. 174, &c. 



11 Quar. Jour. Geol. Soc, Vol. XI, p. 356, and Vol. XVI, p. 151. 



•([ Memoirs Geol. Surv. Ind., Vol. II, p. 19P. 



{ 148 ) 



