60 THE CAMBRIAN. | bull. 81. 



The rocks of this group extend from the American boundary line and cross the 

 tit. John a little above the Meductic, and proceed in a northeast direction toward 

 Barlmrst. * * * 



The strata consist chiefly of grauwacke, grauwacke slate, and clay slate. The grau- 

 wacke may be compared to a very compact sandstone. There are also beds of con- 

 glomerate, containing bowlders and pebbles of almost every variety of rock. The 

 cementing matter is generally calcareous or argillaceous; but it is sometimes silicious, 

 and the beds change imperceptibly into quartz rock. The slates are of different 

 colors; red, blue, and green are often seen. Many of them contain lime, and others 

 will supply roofing slate. 



The local details of the distribution of this series are not given, nor 

 is the locality of the city of St. John mentioned. Portions of the rocks 

 mentioned by Dr. Gesner are, however, now included in the Cambrian 

 group. 



In his third report Dr. Gesner 1 recognizes two series of rocks, both 

 of which are referred to the Silurian age. The upper group consists of 

 limestones, slates, and sandstones, containing the remains of plants, 

 mollusks, etc. The older group is formed of conglomerates, gray slates, 

 sandstones, talcose slates, and the trap beds of Mispeck and Slack 

 Eivers. 



On a map prepared by Dr. James Robb, 2 the geographic distribution 

 of the formations described by Dr. Gesner is outlined, and under the 

 " Cambrian system " we find the indicated distribution of the Cambrian 

 rocks to include Carboniferous, Devonian, Lower Silurian, and Cam- 

 brian as now known. In the text of the volume accompanying the map 

 Mr. J. F. W. Johnston 3 describes the geographic distribution of the 

 rocks and also their general character. He states that the rocks of the 

 Cambrian are distinguished from those of the Silurian by their greater 

 hardness and by their containing less lime. 



In speaking of the rocks referred to the Lower Silurian and Cam- 

 brian, by Gesner and Robb, Mr. J. W. Dawson 4 states that for the dis- 

 tribution of these rocks, as indicated on the map, he was indebted 

 principally to the map prepared by Dr. Robb. Of the rocks he says : 



I do not think that at present there is any good ground for separating the so-called 

 Cambrian rocks from those last mentioned [Silurian], though it is quite probable that 

 they may belong to an older formation, or that they may be older members of the 

 same formation. 



When relating the results of a visit to New Brunswick Prof. W. 

 B. Rogers 5 described, by the aid of a section, the stratigraphic features 

 exhibited at the junction of the older and less ancient groups of strata 

 on the St. John's and Kennebecasis Rivers, a few miles above the city 



1 Third report on the geological survey of the province of New Brunswick. St. John, 1841, pp . 5-11. 



2 [Letter on the geological structure of New Brunswick. 1 Keport on the agricultural capabilities 

 of the province of New Brunswick, by J. F. W. Johnston. Fredericton, 1850, pp. 12, 13. 



3 Report on the agricultural capabilities of the province of New Brunswick. Fredericton, 1850, pp. 

 17, 18. 



4 Acadian Geology, first edition, 1855, pp. 324, 325. 

 'Remarks on the geology of the neighborhood of St. John, New Brunswick. Boston Soc. Nat 



Hist.,Proc, vol. 7, 1861, p. 176. 



