98 A. JR. Sunt — Age of the Dartmoor Granites. 



I would venture to submit this preliminary point to geologists 

 before making any attempt to discuss the volcanic theory of Dartmoor 

 in detail. 



^^B ^^m ^mii 



"Diagrammatic Eeconstruction of Dartmoor. 



It must be understood that this sketch is diagrammatic and has no pretensions 

 to scale, and that it is mainly suggestive and purposely made as simple in its con- 

 ditions as possible. All below the horizontal line, which represents datum, is purely 

 hypothetical ; and all above the curved line, which indicates generally the present 

 surface contour of the Moor and bordering rocks from north to south. This super- 

 structure has been removed. A, represents Carboniferous rocks ; B, Devonian ; 

 C, Granite ; D, Felsite ; E, Volcanic Material and Ejectmenta. The wedge-like 

 intrusion of the granite has tilted and broken through the upper or Carboniferous 

 rocks, and has thrust as well as heaved the lower or Devonian." 



My own pre-Devonian hypothesis was first advanced at the 

 Tavistock meeting of the Devonshire Association ; on which occasion 

 the following epitome of my paper, with the valuable comments of 

 the President, Mr. W. H. Hudleston, F.E.S., appeared in the 

 " Western Morning News." As reporters could have made nothing 

 of so technical a subject, I conclude that the President's remarks 

 were personally revised for the Press, as was my own abstract. 



^'Tlie Age of the Granites of Dartmoor and the English Channel. 



Mr. A. E. Hunt read a paper on the Eelation of the Granites of 

 Dartmoor to the Granites of the English Channel. The author drew 

 attention to the following points of difference between the granites 

 of Dartmoor and those trawled in the English Channel : — The 

 Dartmoor granites were characterized by fracture, by the frequent 

 presence of tourmaline, and were not gneissose. The Channel 

 granites indicated compression, were sometimes hornblendic, and 

 were associated with gneisses. The Dartmoor granites were inter- 

 sected by injected and infiltrated veins. No veinstones (though such 

 were very durable) had been forthcoming from the Channel. The 

 quartzes in the Dartmoor granites and in both classes of veins con- 

 tained fluid inclusions of brine, with cubic crystals of salt. No salt 

 had been detected in the Channel granites. Chiastolite occurred on 

 the borders of Dartmoor, kyauite in the Bolt schists bordering the 



