DEFORMATION OF ROCKS 629 



nioclritinu,' itself easily to its new position, and by recrystallization 

 has taken on a massive character. The thin belts of gneiss 

 within the limestone have been broken to fragments. The frag- 

 ments in the limestone matrix have ground against one another 

 until they became well rounded. They are disseminated through 

 the limestone. As the layers of gneiss are thicker and more 

 numerous near the base of the limestone, this part of the forma- 

 tion appears as a limestone containing numerous bowlders and 

 smaller fragments of gneiss resting upon a gneiss formation. 

 Thus an unconformable contact was inferred when the area was 

 first examined, but an extended and close examination of the 

 region showed all stages of transition, from the phase of the 

 rock which appeared to be a true conglomerate to that in which 

 the thin layers of gneiss are interstratified with limestone. Sim- 

 ilar phenomena have been observed in the Original Laurentian 

 area and in the Marquette district of Michigan. 



C. R. Van Hise. 



