114 ROYAL SOCIETY OF CANADA 



the Laurentian was regarded as divisible into a lower and an upper 

 portion which were supposed to be the equivalents of the Laurentian 

 of the Province of Quebec, the lower division representing the Funda- 

 mental gneiss of that province, while the upper was regarded as 

 similar in age to the Grenville series. The former comprises granites, 

 sometimes having a gneissic structure, gabbros, diorites, etc. ; the 

 latter consists largely of crystalline limestone associated with slates, 

 schists and sandstone or quartzite, with which were also included 

 masses of igneous rocks. 



The second great group, known as Huronian, was divided into 

 three parts, the Coastal, Kingston and Coldbrook, having an aggregate 

 thickness of many thousand feet. Large portions are of igneous 

 origin, and the upper part of the Coldbrook was supposed possibly 

 to form transition beds into the base of the Cambrian. Both of these 

 series or systems were so established from the fact that in part at least 

 they were regarded as underlying the fossiliferous Cambrian system 

 proper, or as then understood, and in consequence they were fre- 

 quently known under the general term Pre-Cambrian. The upper 

 part of the Coldbrook comprised a considerable thickness of reddish 

 and purple, sometimes grayish sediments, with certain areas of igneous 

 felsitic rocks, all of which were held to underlie unconformably the 

 gray and dark slates and quartzite of the St. John group or primordial 

 Silurian as developed about the city of St. John. 



The study of this lower portion was next taken up by Drs. 

 Matthew and Walcott, and collections of fossils were made, which 

 shewed that these hitherto somewhat doubtful rocks, which were 

 styled Etcheminian, might constitute the lowest fossiliferous zone of 

 the Cambrian system. They were in consequence removed from the 

 Coldbrook Huronian. A partly igneous series at the base of the 

 recognized Etcheminian was also included in the Cambrian terrane 

 under the name "Coldbrookian." The series as a whole is composed 

 of slates, quartzite, limestone and thin conglomerates and was arranged 

 under four heads known in ascending order above the Coldbrookian, 

 as Etcheminian, Acadian, Johannian and Bretonian, the last passing 

 upward into the lower Ordovician, with a fauna of graptolites, etc., 

 similar to forms found in the Levis division of the Quebec group, 

 as developed at and near Point Levis, opposite the city of Quebec. 

 Throughout all these Cambrian divisions about St. John there is an 

 apparent conformity, except where the arrangement of the several 

 divisions is broken by well-defined lines of faulting. 



The position of the Cambrian on the underlying rocks was found 

 to vary considerably at different points. Thus to the east of St. 

 John the lowest portion rests on the Coastal division of the Huronian, 



