132 ROYAL SOCIETY OF CANADA 



Bald or Sagamook Mountain, the prominent eminence overlooking 

 Xictor Lake at the head of the Tobique river, and the second about four 

 miles to the southeastward, from the " Green range " of mountains, 

 near the sources of the Nepisiguit. 



Porpihyry. Section 5765. Bald or Sagamook Mountain. " Tilie 

 thin section is composed of large and small phenocrysts of microcline, 

 a number of orthoclase, many smaller lath-like individuals of acid 

 plagioclase, felspar, grains of magnetite and a few zircons lying in a 

 microerA'stalline ground. 



The abundant feldspar phenocrysts are often bent or broken or 

 otherwise show the effects of strain to which the microcline structure 

 of some of them is probably due. The ground surrounding many of 

 the phenocrysts and in spots throughout the section is exceedingly fine- 

 grained and stained reddish. Very distinct spherulitic structures are 

 common and usually have been developed around larger grains of the 

 graund or a small grain of iron ore or zircon. Much of the ground is 

 nearly cryptocrystalline in grain, but, where it is coarser, it is seen to 

 be a granular aggregate of quartz and feldspar, the latter probably 

 chiefly orthoclase. Green biotite occurs in small, irregular flakes 

 through this ground. 



The rock appears to be a rather acid variety which, were it not for 

 the absence of quartz-phenocrysts, would be classed as a quartz-porphyry. 



Section 5760. Green Eange., Nepisiquit river. Porphyrite Tuff. 



The thin section is composed of a very fine-grained, nearly crypto- 

 crystalline ground in which lie a number of feldspar individuals and 

 large and small, irregular or angular fragments of at least two varieties 

 of valcanic rock. 



The individuals of feldspar are of both orthoclase and plagioclase 

 feldspar, and usually have rectangular outlines. Several of the plagio- 

 clase grains have been fractured and their component parts slightly 

 separated, showing that the rock has been subjected to strain. 



The more noticeable of the rock fragments are very dark from some 

 pigment, and consist chiefiy of small lath-like feldspars, probably plagio- 

 clase. The more abundant variety of rock fragments occurs' in forms 

 greatly varying in size and shape. They are generally of a light yellow 

 colour and often contain much chlorite. Between crossed niçois they 

 are seen to be composed of a fine grained granular aggregate apparently 

 chiefly of feldspars. The grain of this latter variety varies somewhat, 

 tut is always considerably coarser than that of the ground.^* 



One other area of undoubted Silurian rocks requires notice as being 

 marked by the evidences of volcanic activity. This is the vicinity of 

 the Baie des Chaleurs. Here rocks of igneous origin are met with in 



