NEW BRUNSWICK — ACADIAN GROUP. 637 



2. Lower Silurian of the south shore of New Brunswick.— The Acadian 



group. 



The city of St John stands on tlie outcropping edges of a thick 

 band of hard slaty rocks underlying the Devonian beds, which appear 

 at the southern end of the city. These St John rocks were until 

 recently of uncertain age. Believing them to underlie conformably 

 the last-mentioned series, I had supposed them to be Lower Devonian 

 or Upper Silurian, but Mr IVIatthew has ascertained that they are 

 really unconformable to the overlying formation ; and more recently 

 the discovery of fossils by that gentleman and Mr Hartt in the lower 

 part of the series has set the question at rest. 



The general character of the formation is thus given by Mr 

 Matthew :— " It consists of a gray clay slate often sandy, the layers 

 of which present glistening surfaces, owing to the abundance of minute 

 spangles of mica. This rock very frequently becomes very fine in 

 lamination and texture, and dark in colour. Four thick bands of this 

 kind occur, the uppermost of which is a black papyraceous shale. 

 The three bands of coarser shale which alternate with them include nu- 

 merous layers of a fine compact gray sandstone, from a few inches to ten 

 feet or more in thickness ; a few are so highly calcareous as to become 

 almost limestones. The surfaces of the layers in the coarser beds are 

 frequently covered with worm-burrows, ripple marks, shrinkage cracks 

 or scratches— apparently made by creatures gliding through the 

 shallow waters in which they were deposited, and other evidences 

 indicating that the slates are in great part of littoral origin." 



The following section of the series at St John is given by the same 

 observer : — 



,. , ^ , feet. feet. 



' 1. a. Gray sandstone or quartzite 50 



h. Coarse gray arenaceous shale. 



[This and the preceding are passage-beds from the 

 Coldbrook or Huronian group.] 



c. Gray argillaceous shale, rich in fossils : Paradoxides, 



Orthis, Conocephalites, Oholella. \. 150 



d. Black carbonaceous shale, full of fossils: Para- 



doxides, Conocephalitea, Orthis, Discina, Ortho- 

 ceras, and a thin subtriangular shell resembling 

 Theca, all much distorted .... 200 



2. a. Dark-gray shales, with thin seams of gray sandstone 220) 



b. Coarser gray shales, with gray flagstones . . . 200 >- 550 



c. Gray sandstone and coarse shales : JAnfjula, etc., . ] 30 j 



3. a. Dark-gray shales, finely laminated .... 450 ) 

 b. Black carbonaceous and dark-gray argillaceous shales V 750 



more compact than the last 3O0 ) 



4. Shales and flags resembling 2 a and & .... 800 1?') 



Carry forward 2300 



