578 THE UPPER SILURIAN. 



the Nepisiguit which belong to New Brunswick, and the high lands 

 of Rimouski and Gaspe which belong to the Province of Quebec. 



This belt of very ancient rocks was probably a physical barrier even 

 as early as the Upper Silurian period ; for on passing it we find in the 

 valleys of the Restigouche and the neighbouring streams beds of 

 highly calcareous and fossiliferous Upper Silurian rock identical in 

 character with those of Gaspe, and differing both in mineral character 

 and the assemblage of fossils from those which we have just been 

 studying. The southern limit of this Upper Silurian area, in so far 

 as it is known, may be seen on the map ; and its structure may be 

 learned from the following description by Professor Hind of the sec- 

 tion at Cape Bon Ami, near Dalhousie. The section is in ascending 

 order, and the dips are to the northward at an angle of 45°. 



1. Trap. 



2. Calcareous shales. 



3. Trap or trappean ash, more or less stratified, and with veins of 

 carbonate of lime and quartz. 



4. Calcareous shales and honestones, weathering buff or pale yellow. 



5. Trap, vesicular, hard and black, weathering red. 



6. Calcareous shale and Mmestone, with honestone. Many layers 

 are fissile and shaly, weathering buff, others ai*e hard and silicious. 

 The limestones contain Favosites Gothlandica, Strophomena rhom- 

 boidalis, etc. In the upper part of this series there appears to be a 

 conglomerate 14 feet thick, capped by honestone 36 feet thick. 



7. Massive trap. 



8. Limestone highly fossiliferous. Among its fossils are Favosites 

 Gothlandica, F. polymorpha, F. basaltica, Strophomena rhomboidalis, 

 S. punctulifera, Calymene Blumenbachii, Atrypa reticidaris. 



9. Trap, highly ferruginous* 



It is instructive to observe the large amount of bedded trap or 

 volcanic ash in the above section. This accords with the presence 

 of large quantities of apparently interstratified igneous rock in the 

 Kingston group and in the Cobequid Mountains, as already noticed. 

 Such interstratified volcanic matters are abundant in some parts of the 

 Silurian of Great Britain. They are comparatively rare in other parts 

 of Nova Scotia, though beds of this kind occur in New Canaan. 

 Similar traps occur in Gaspe, but they are absent from the typical 

 Upper Silurian of New York and Western Canada. Their presence 

 indicates the recurrence of volcanic eruptions at frequent intervals 

 during the Upper Silurian period. 



A collection of fossils from the beds at Dalhousie and its vicinity 

 * The total thickness of the above series is not stated by Professor Hind. 



