OF SILUEIAN AND DEVONIAN. S S 



At Arisaig, iu eastern Nova Scotia, is a section of Sihxrian rocks wliich, owing to 

 the fauna which it contains, has been studied with much care. These consist of : — 



Feet. 



A — Grey argillaceous and arenaceous shale 200 



B — Dark shales and ferruginous shales 170 



B' — Shales more compact than B, and of a lighter color '\ 



C — Shales harder than the last, and more calcareous r 500 



D — Grey and colored shales, with limestone bands 3 



870 

 The first of these was referred by Dr. Honeyman, some years ago, to the Mayhill 

 Sandstone, the second to the Lower Ludlow, the third to the Amestry Limestone, and 

 the fourth to the Upper Ludlow. In a late publication he has revised this opinion, 

 and would regard A, B, and B' as Medina and Clinton, or in part of Hudson Eiver age. 

 This would bring his determination of these beds in accordance with Mr. Billings' 

 results in the Island of Anticosti. Further information on the age of these beds may be 

 gathered from the Acadian Geology,' where it is said that "the general assemblage 

 [of fossils] in the Group D is, on the whole, not unlike that of the Clinton, but is of such 

 a character as to warrant the belief that we may have in these beds a series somewhat 

 higher in position." 



In southern New Brunswick there is a series of measures of Silurian age, iu which 

 the succession is, lithologically, not unlike that at Arisaig. On Passamaquoddy Bay the 



following succession has been observed : — 



Feet. 



Div. 1. — Hard grey and olive grey slates argillites 400 



Div. 2.— Black and dark trey siliceous shales, with very distinct alternating color 



bands in the lower half t'-O 



Div. 3. — Grey sandy flags and shales 350 



Div. 4. — Greenish and reddish sandstones and shales 310 



Div. 5. — Dark porphyritic red felsite •>00 



1,980 



The beds in the middle of this series, as at Arisaig, consist of finely laminated dark 

 grey and black shales, and although no fauna has yet been found in them that will 

 definitely fix their horizon, it is approximately determined by the fauna of Div. 3. This 

 has been examined by Mr. H. M. Ami, of the Geological Survey of Canada, and found to 

 correspond to that of the Niagara group." 



Thus, in three districts of Acadia, the lower measures of the Silurian series are 

 represented by bitumenous shales and limestones to the north, and dark carbonaceous 

 shales to the south, which j)i'csumably are contemporaneous, and which, by their fauna, 

 so far as it is known, are of the age of the Clinton groirp. It is in this part of the series 

 (Div. 2) that the fish remains described in this article were found. They occur in the 

 mass of strata included in the 6*70 feet mentioned iu the section at page 165 of the Eeport 

 of the Geological Survey of Canada, IS'TO-l. 



' Page 556. 



^ From earlier and loss complete collections of the fossils of this division, the late Mr. E. Billings referred it, 

 about eighteen years ago, to the Lower Helderberg horizon. The period marked by Divs. 3 and 4 was one of 

 transition with elevation of the sea-bottom, accompanied by volcanic disturbances. Thus resulted much local 

 variation of the fauna, so that the exact age of these division s (and of Div. 5 which is local), is still open to question. 



