Professor Ramsay's Address. 511 



cated. Such shrinkage and crumpling, however produced, when 

 most intense and on the greatest scale, is always (where I know it) 

 accompanied by the appearance of gneissic or other metamorphic 

 rocks, and of granite or its allies ; and it has often been the custom 

 to attribute the disturbance of the strata in such mountain ranges 

 and their metamorphism into gneiss, crystalline marble, and the like, 

 to the intrusion of granite. But my opinion is that with regard to 

 gneiss and granite the first has been produced by processes of meta- 

 morphism which I cannot now enter upon, and without any necessary 

 connection with the intrusion of granite, while granite itself is often 

 simply the result of extreme m.etamorphism, having passed through 

 and beyond the stage of imperfect crystallization, characteristic of 

 gneiss, into that state of more perfect crystallization which marks 

 well-developed granite. If this be so, then, so far from the intrusion 

 of granite having produced such mountains as those I speak of, both 

 gneiss and granite would rather seem to be results of the forces that 

 formed the mountain chains, I cannot tell how, but possibly connected 

 with the heat produced by the intense contortion of such vast masses 

 of strata, the parts of which now exposed by denudation were then 

 deep underground. There is, however, a difficulty here, perhaps 

 insuperable, and which my knowledge does not enable me to grapple 

 with ; viz., that if the shrinkage that contorted the strata was slow, 

 the heat resulting from it might never have attained sufficient inten- 

 sity, to haA'C produced, with the aid of alkaline waters, those common 

 metamorphic masses, known as gneiss, granite, syenite, etc., and 

 others less commonly recognised as metamorphic, such as some of 

 the quartz poi-phyries, for the heat thus generated may have escaped 

 as fast as it was formed. But I cannot now enter on these details. 



It has often been customary to speak of the Cumbrian mountains 

 as a great dome, forces from below having heaved up the strata 

 towards a central point, from whence the main valleys radiate as 

 great rents produced by that upheaval. But the strata of Cumber- 

 land are not dome-shaped in the true geological sense. If it were 

 so, the strata ought to dip from the centre. But instead of that 

 we find Lower and Upper Silurian strata from the equivalents 

 of the Llandeilo flags to the Ludlow beds though contorted, yet 

 forming an ascending series all across Cumberland from Cocker- 

 mouth to Ambleside, with an average south-easterly dip. There is, 

 indeed, nothing cone-Kke in the manner of their arrangement, and 

 the igneous rocks associated with the Cumbrian strata have partaken 

 of disturbances of the same ages as those that heaved up the Silurian 

 rocks of Wales. Afterwards the whole series was planed across by 

 marine denudation before the age of the Old Eed Sandstone of the 

 area ; and then, but chiefly at later periods, the valleys were scooped 

 out from a great tableland, especially after the removal by denuda- 

 tion of the Carboniferous rocks which at one time probably cased and 

 concealed the whole of the Silurian strata. In this manner the 

 character of the mountains of the country was produced, the harder 

 masses being apt to form the heights, craggy, yet often rounded by 

 glacial denudation. 



