304 A. Wand/he — Study of Cape Neddick Gabbro. 



Summary. 



The striking features of this Cape Neddick locality 

 are: 



1. The intrusive apparently occupies a zone of tension 

 the emplacement having been effected by lateral creep 

 and by bodily thrusting apart the enclosing walls. 



2. Stoping and marginal assimilation are both indi- 

 cated but seem to have been rather insignificant processes 

 during the emplacement of the gabbro. 



3. The gabbro shows a banded phase that is best 

 explained by the rhythmical reduction of pressure within 

 the gabbro by the escape of volatile components during 

 consolidation. 



4. Differentiation by crystal settling seems indicated 

 and the basic phase seems later to have intruded the acid 

 phase. 



5. The contact actions indicate the tendency of the 

 quartzite near the contact to approach a quartz diorite in 

 composition, the gabbro in turn becoming siliceous by 

 absorbing quartzite. 



