470 E. A. DALY LITCHFIELDITE AXD SODA-SYEXITES OF MAINE 



bon dioxide was one of the gases involved. Chlorine participated in the 

 formation of the sodalitic schliers; water in the formation of lepidome- 

 lane and other minerals. The influence of gases is further illustrated in 

 the thorough impregnation of the schists by the litchfieldite magma for 

 distances of 5 to 15 centimeters from the contact of schist and intrusive. 

 The origin of the magmas is a problem which can not be intelligently 

 discussed without additional information concerning the petrography of 

 the schist terrane and without a solution of the present mystery as to the 

 nature of the terranes beneath the visible sediments. Further observa- 

 tions on the igneous history of the whole region are also necessary. Any 

 future attack on the problem must include the consideration of three 

 possibilities: (1) The magmas may be purely juvenile. (2) They may 

 be purel}^ resurgent, due to "selective solution" (Lane) among certain 

 components of the visible schists , or underlying formations. ( 3 ) The 

 magmas may include both juvenile materials and resurgent materials — 

 that is, country rock dissolved by juvenile magma. The cause of the local 

 deficiency of silica, signalized bV the crystallization of nephelite, cancri- 

 nite, and sodalite, is a related question. The small size of each of the 

 undersaturated bodies is not a feature favorable to the prevailing dogma 

 that nephelite syenite is a differentiate of a primitive magma specially 

 rich in alkalies. 



