i jo pkcceediycrs of tee geological society. 



Sfmmaet. 



I am unwilling to add to the length of this already too long 

 Address by offering a comparison of the phenomena which I 

 have tried to portray to you with those which have been described 

 in other countries. Nor do I propose to enter now upon a discus- 

 sion of the theoretical questions arising out of the array of fncts 

 laid before you. My object has been to present a connected narra- 

 tive of ascertained knowledge regarding the successive epochs of 

 volcanic energy in this country, unencumbered with reference to 

 regions beyond our immediate surroundings. But it will not, I 

 hope, be deemed an inappropriate prolongation of my subject if, in 

 conclusion, I attempt to place before you some of the facts of larger 

 import and wider interest which such a narrative may be made to 

 contribute towards the investigation of the nature of volcanic action. 



1. In regard to the broad features of the distribution of volcanic 

 action, it is important to remember the position of the British area 

 along the western or oceanic border of the European continent. And 

 when we look at the portions of that area which have been the 

 scenes of volcanic activity, we observe how they follow a general 

 linear north and south direction, parallel to the margin of the con- 

 tinental plateau. They are ranged along the greatest length of 

 these islands, from the south of Devonshire to the far Shetlands. 

 A'^et east of a line drawn from Berwick to Exeter thcj^ cease to 

 appear. All through the eastern portion of England, though the 

 geological formations range from the Carboniferous Limestone to 

 the latest Pleistocene deposits, and are abundantly exposed to view, 

 no trace of volcanic rocks has been met with, unless we include in 

 that category the various dykes of the northern counties. The 

 recurrence of eruptions along the western, and their absence in the 

 icast erh tract, are two of the most obvious and striking facts in the 

 history of volcanic action within our region. 



2. Another not less remaikable feature is the persistence of 

 volcanic activity within that western tract. I have brought before 

 you the evidence which shows that from the primeval time vaguely 

 termed Archaean, onward to that of the older Teitiary soft clays 

 and sands of the south-east of England — that is to sa}^, through 

 b}^ far the largest part of geological history, as chronicled in the 

 stratified crust of the globe — this long strip of territory in the west 

 of Europe continued to be inteimittently a theatre of volcanic 

 action. In the great divisions of Palaeozoic and Tertiary time 



