158 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 15, 



On the north, at the Artillery Lines, the rocks in a descending order 

 are : n, nodular trap ; t, .tertiary deposit, thin and indurated in the 



Fig. 3. — Section at the Artillery Lines, Takli. 



Nag River. 



n. Nodular trap-rock. s. Sandstone. 



t. Tertiary deposits. p. Pegmatite. 



a. Amygdaloidal trap. gn. Gneiss. 



higher position, and thick and soft in the lower ; a, amygdaloid, 

 and s, sandstone. On the south near the river we find : s, the same 

 sandstone ; p, pegmatite, and gn, gneiss. For the sake of clearness 

 I enlarge the section of the rocks on which the Artillery Lines are 

 built (fig. 4). Here, as before, n is nodular trap ; t, tertiary stratum, 



Fig. 4. — The strata at Artillery Lines. 





n. Nodular trap. t. Tertiary beds. s. Sandstone. 



clayey and soft, and s, sandstone. From the argillaceous deposit 

 portions have been taken up into the body of the volcanic rock, and 

 sometimes as high as its surface. Such detached fragments have 

 furnished us with the greater number of the vegetable remains for 

 which Takli is remarkable. Where the trap comes into contact with 

 the base of these masses, it is seen not to be nodular, as it is every- 

 where else, but vesicular. 



Now the question arises, Is the thinner and harder deposit on the 

 slope of the hill in fig. 3 the same as the thicker and softer stratum 

 at the lower level of the Artillery Lines ? I have no hesitation in 

 aflirming that it is ; for in digging through the hill, no deposit but it 

 is met with until the sandstone is reached, — not to mention that the 

 same genera and species of shells are obtained from both. Now as 

 in fig. 4 the single layer of lava has become vesicular or nodular 

 according as it lies below or above the detached pieces of the clayey 

 deposit, so we have only to suppose that part of the same lava-flow 

 at the present site of the hill in fig. 3 went above, and part found 

 its way at the bottom of the deposit, and we discover the reason of 

 the upper trap being nodular and the lower vesicular. The origin 

 of the vesicles in the lower trap would appear to be the exudation 

 of moisture from the stratum under which it was intruded ; while 



