ANNIVERSARY ADD1U":SS OF THE PRESIDENT. 145 



of the Phlegrccan fields than of Etna and Vesuvius. If this 

 surmise bo true, we may expect yet to recognize many little necks 

 scattered over the volcanic district and marking the positions of 

 some of these vanished cones. 



One of them, which has not before been noticed, may, I think, 

 be shown to have stood near Grange at the mouth of Borrowdalc. 

 In the little Comb Beck, the JSkiddaw Slates are pierced by a mass of 

 extremely coarse agglomerate, forming a rudely circular boss. The 

 slates are greatly disturbed along the edges of the boss, so much so, 

 indeed, that it is in some places difficult to draw a line between them 

 and the material of the agglomerate. That material is made up of 

 angular blocks, varying in size up to three feet long, stuck in every 

 position and angle in an intensely indurated matrix formed 

 apparently of comminuted debris like the stones. The blocks con- 

 sist of a finely stratified shale, which is now hardened into a kind of 

 hornstone, with small felsitic fragments. I could see no slags or 

 bombs of any kind. There is no trace of cleavage among the blocks, 

 nor is the matrix itself sensibly cleaved. That this is a small 

 volcanic neck cannot, I think, admit of doubt. It has been blown 

 through the Skiddaw Slates, and is now filled up with the debris of 

 these slates. Its formation took place before the cleavage of the 

 strata, and its firm position and great induration enabled it to resist 

 the cleavage which has so powerfully affected the slates and many 

 members of the volcanic group. 



It was the opinion of my predecessor, Sir Andrew Eamsay, and 

 likewise of Mr. AVard, that the Cumbrian volcanic action was 

 mainly subaerial. This opinion was founded chiefly on the fact 

 that, save at the bottom and top of the series, there is no evidence 

 of any interstratified sediment of non-volcanic kind. The absence 

 of such interstratification may undoubtedly furnish a presumption 

 in favour of this view, but, of course, it is by no means a proof. 

 We might conceive that the eruptions followed each other so con- 

 tinuously on the sea-floor and at so great a distance from land that 

 no deposition of sand or mud from the outside could sensibly aff'ect 

 the accumulation of volcanic material. I confess that the well- 

 defined stratification of many of the fine tuff's is rather suggestive 

 to my mind of submarine than of subaerial accumulation. At the 

 same time, there seems no reason why, here and there at least, the 

 volcanic cones should not have risen above the water, though their 

 materials would be washed down and spread out by the waves. It 

 is worthy of remark that in the exposures of the Eorrowdale 



