159 FKiniOH : CEOT.OGY AND COAL RESOURCES OF KOREA, C. i>. 
an intrusive character ; but at one point, where a stream cuts 
across the line of outcrop of these vesicular lavas and associated 
altered sediments, it is found that these curious rocks do not 
continue in depth, typical massive Barakar sandstone being at once 
exposed. The evidence of the streaiii suggests a superficial distri- 
bution for the lavas. This agrees with the vesicular and, sometimes, 
almost pumiceous character of the lava and conflicts with its linear 
distribution and the altered character of the immediately associated 
sediments. In the short time at my disposal, I examined all 
the evidence that was immediately available, but was unable to 
reconcile the conflicting evidence with either hypothesis. Under 
the microscope the rock is seen to show extremely numerous felspar 
microlites in a colorless to black glassy matrix, often vesicular. 
In the most coarsely crystalline variety, the laths are found to 
be labradorite with an extinction of 39° referred to the albite 
twinning. They are set in a glassy matrix containing skeleton 
magnetites, but no augite. The rock seems, therefore, to be an 
unusual variety of andesite, corresponding in composition to the 
groundmass of typical andesites, the ferromagnesian silicates being 
absent. 
On the Kaoria Nala and its tributaries, I found several other 
obscure occurrences of this series of vesicular lavas and included 
sediments, usually in the form of loose blocks ; but for want of 
time I was unable to track the fragments to their respective 
sources and thereby possibly obtain the key to the solution of 
the problem. 
It must be noticed that if we ascribe a superficial origin to 
these rocks we are confronted with one of two alternatives. Either 
the lavas were extruded during the course of deposition of the 
Barakar sandstones at a fairly low horizon in the series, or they 
were erupted in recent times after denudation had cut down 
the Barakars to their present level. So far as I am aware there 
is no evidence of volcanic activity anywhere in India in the whole 
of the Gondwana period until Rajmahal time, nor does the alter- 
native of a recent age seem in the least degree possible. If we 
adopt the hypothesis that these rocks, in spite of inconsistencies, 
are intrusive, then we are provided with a possible source in the 
volcanic intrusions of Deccan Trap age, of which, as already related, 
there is abundant evidence in the form of the doleritic sill and 
dykes. It is true that the Chirmiri rocks are of andesitic not 
