IIAf. XIII 



SCHISTOSE ROCKS 





will carefully examine the undoubted 

 which have tx d among schistose rock*, be will 



in many places be able to uace a complete passage 

 an unmistakable massive eruptive rock into tbe 

 typical acbist Coarse pegmatites, when they have 



n the influence of the tame shearing movements, 

 have been crushed down into fragments, which may be 

 traced getting smaller as they recede from the main body, 



until they disappear in a finely streaked felsitic substance 

 (which might readily be mistaken lor a rhyolite), or in a 



. ; : i :..-: 1 ' , k : < . ' : . 



originally, no doubt, pyroxenic, have been changed into 

 fissile hornblende-schists. Their central parts, where the 

 dykes are broad, may still retain the original massive 

 strut -lure, or may present a series of cores preserving that 

 structure inside, but passing externally into schist ; while 

 the marginal portions may pass into the most com- 

 pletely schistose condition. In the example shown in 



