RECORDS. 499 



accompanied by ash beds and breccias. Twenty- two analyses 

 of the various types were given. 



The character of the region as a petrographical province was 

 discussed at some length. Chemically it was shown to be rich in 

 alkalies, especially Soda, low in Lime and very low in Magnesia, 

 and rather acid. The low Magnesia was commented on, and the 

 occurrence noted of many minerals in these rocks as varieties 

 poor in this oxide which are usually rich in it, as Lepidomelane, 

 Fayalite and Glaucophane. The usually high ratio of FeO to 

 Fe20.^ was discussed and it was pointed out that in most of the 

 rocks FeO is extremely high, replacing MgO, while in the 

 foyaitic group it is much lower. Iron oxides tend to vary with 

 soda. Soda is constantly higher than Potash, but the molecular 

 ratio varies a great deal, being about i.io in the granitic rocks, 

 higher in the foyaitic group, and very high in the basic, the 

 ratio in nearly every case approximating to whole numbers. 

 This differentiation of Na.,0 was commented on and its impor- 

 tance pointed out. 



Comparisons were instituted with other regions and the great 

 resembance to the rocks of southern Norway were described. It 

 was shown that probably the chemical composition of the magma 

 as a whole approaches that of a Nordmarkite, and that it is rather 

 acid, as in Norway. The relations of the rocks of Essex county 

 to those of the other alkali-rich regions of the Atlantic slope were 

 also discussed. 



The paper was discussed by Professor Kemp and others. 



A. A. JULIEN, 



Secretary pro tern. 



