8 TRAPS AND INTERTRAPPEAN BEDS 



orio-in such as the intertrappean '' frog beds" of Bombay, and the num- 

 mvxlitics of the Rajpipla hills. The ouly departure from absohit^ hori- 

 zoutality to be seen in the traps of the Deccan is frequently no more 

 than may be due to the lenticular form of the beds. Yet the separate lava 

 flows are of no great thickness, the average in two sections which I 

 measured, upon the railway on the Bhore and Thull Ghats, was apparently 

 64 and 87 feet respectively, but really less, for the distinction between 

 the beds could, in most cases, only be distinguished by lithologieal charac- 

 ters • and when, as must frequently have been the case, two or more beds 

 of similar appearance and composition occurred together, they were fre- 

 quently measured as one. Indeed many of the more amygdaloidal flows 

 appeared to be made up of smaller flows from 6 to 10 feet thick, distin- 

 guished by being highly amygdaloidal above, less so in the middle, and 

 marked towards the base with long sub -cylindrical vertical pipes, of 

 small diameter, filled with zeolite ; the more amygdaloidal character of 

 the upper part of each stratum being apparently due to its having been 

 orio-inally more vesicular near its surface. But even supposing that 

 these apparent distinctions are accidental, some distinct crystalline 

 flows in both sections do not exceed 15 feet, and even assuming the 

 average to be that given above, it is evident that the lava must have 

 been poured out in a very liquid state to have spread so evenly over a 

 surface so nearly horizontal. I think it worthy of consideration 

 whether some of the beds, especially the more earthy ones, may not 

 have been volcanic muds, and not true lavas. 



6. Volcanic foci. — The absence of distinct volcanic foci has often 

 been noticed. Of course cones of loose scorise would be too easily re- 

 moved by denudation to be left, and if the nuclei of the volcanoes were of 

 basalt (and they probably were so) similar in character to some of the lava 

 flows, it would be extremely difficult to recognise them. Still it is curious 

 that so few should have been met with. I have, I think, seen one or two 



( 144 ) 



