METAMOEPHIC ROCKS OF SOUTH DEVON. 733 



effects of pressure are seen in the general folding of the "beds with a 

 dominant strike from east to west, and in the high dip of the strata, 

 sometimes even vertical, thus indicative of a great thrust along a 

 S. to jN". line, no douht in connexion with that whieh caused the 

 folding of strata in the long axial region, stretching from Devonshire 

 away to the Hercynian range. 



III. In tracing stratigraphical relations among the northern 

 metamorphic rocks, I have pointed out extensive examples of inter- 

 bandings there occurring. Mica- and chlorite-schists alternate in 

 thin layers or thicker beds over a fairly large area in the north, as 

 they do also, perhaps more locally, in other parts, reminding one 

 of the descriptions given by Prof. Bonney, in his Presidential 

 Address *, of rocks in more than one locality, where he asserts 

 the necessity of some material distinctions in the original beds. 

 The mineral bands in these South-Devon rocks may be of an 

 inch or a few inches in width, but often they are to be measured 

 by feet, and, as I have shown, the alternating and generally even- 

 bedded series south of Halwell Wood consist of masses, on an 

 average, some 50 feet thick. The limit of each bed is often abrupt 

 and distinctly marked off from the next in succession, although 

 many gradations can be obtained by collecting from particular and 

 often separated areas. If it should be that we have here an 

 example of a stratification-foliation, this will lead us back to an 

 anterior epoch when the great Channel mountains were not, and 

 will suggest to us the wide problem of the origin of these rocks 

 and the question of a primary metamorphism. 



I cannot conclude without expressing my indebtedness to Prof, 

 Bonney, not only for the help his paper afforded me, but also for 

 valuable suggestions and kind encouragement in this endeavour t© 

 carry on his work in the south of Devonshire. 



* Quart. Journ. Geol. Soc. (1886),. p. 46. 



