THE CRYSTALLINE ROCKS NEAR ST. JOHN, X. B. 17 



rocks around the city, and especially the igneous ones. 

 The facilities for the stud^^of these have in late years been 

 greatly increased by the use of thin sections of the rock, 

 which can be examined under a polarizing microscope ; 

 thus bringing to light many interesting structures, imper- 

 fectly, or not at all seen in the opaque specimen. 



The pioneer geologist in New Brunswick was Dr. 

 Abraham Gesner, who conducted between 1839 and 1843, 

 under the rrovincial Government, a geological survey, 

 which published a number of reports on the geology of 

 the province, dealing chiefly Avith its economic aspects, 

 the prospects for mining and agriculture. After the 

 union of the provinces, a second and more thorough 

 .survey was made under the Dominion Government, and 

 the results of this survey in southern ISTew Brunswick 

 were published in the Report of 1871, and later ones. 

 The structural geology of this paper is mostly summarized 

 from these reports. The field-work for this part of the 

 pi-ovince was done by Dr. L. W. Bailey and Dr. G. F. 

 Matthew, President of this Society, joined later by Dr. 

 R. W. Ells. The map accompanying this paper will more 

 tully show the geology of the vicinity of St. John, being 

 on a larger scale than that published by the Canadian 

 Geological Survey. 



Saint John is built on the upturned edges of grey 

 Cambrian slates, which underlie most of the peninsula 

 forming the city proper, and the "Valley" to the north 

 of it. At the end of tlie peninsula is a small remnant of 

 very similar slates of Devonian age, separated from the 

 Cambrian by a band of older trap rock. The face of 

 the hill back of the Valley is composed of hard and 

 fine-grained flinty felsites, very much cracked up and 

 jointed ; and behind these lie limestones, quartzites and 

 gneisses, ft^rming a rough, broken country A\hich 



