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Prof. J. Jolv on the Radioactivity of 



are calcareous. It is not probable that these synclinal folds 

 extend very deeply. The tunnel next enters the highly 



metamorphosed rocks of: the St. Gothard Massif. These 

 extend for 7i kilometres, and include the most varied schists 

 and intrusives ; all showing the effects of intense dynamical' 



