Williams — Geology of Arisaig-Antigonish District. 243 



unravelling the stratigraphic sequence of the Silurian section 

 exposed along the coast at Arisaig — a section unique because 

 of its completeness, fossil contents, and decided European affini- 

 ties. Later workers on the Silurian rocks have been Dr. H. 

 M. Ami* of the Geological Survey of Canada, and Professors 

 Schuchert and Twenhofel.f In 1886 Hugh Fletcher:}: of the 

 Geological Survey of Canada published his final report on 

 Pictou and Antigonish Counties, which gives the best general 

 account of the district so far printed. Dr. Ami carefully 

 described the Devonian strata of the area and published an 

 account of the lower vertebrates obtained from them. Numer- 

 ous other geologists have directly or indirectly added to the 

 information relating to the region about Arisaig, which accord- 

 ing to Honeyman became during his later life a household 

 word in the homes of Canadian geologists. 



Physiography. 



Not only to the geologist and physiographer but to the 

 casual traveler as well, the Arisaig-Antigonish district is a 

 region of interest and delight. Possessing for Nova Scotia a 

 maximum difference of relief, the area presents to the visitor 

 during the summer months a delightfully green expanse of 

 lowlands and rolling uplands, which flank a steep-scarped and 

 generally wooded plateau. Trout streams, often several miles 

 in length, occupy picturesque gorges in the plateau and uplands 

 and flow in gently graded valleys across the lowlands. The 

 plateau in places attains a height of 1000 feet and has an aver- 

 age elevation of about 800 feet. The uplands vary from 200 

 to 400 feet or more in height and the lowlands occupy the 

 lower elevations down to about 50 feet above sea-level, 



The plateau quite definitely belongs to the land forms recog- 

 nized in the Maritime Provinces by R. A. Daly§ as being the 

 remnants of a Cretaceous erosion surface of low relief, and the 

 uplands belong to the secondary erosion surface of Tertiary 

 time recognized by Daly in Nova Scotia. However, because 

 of the resistance offered by the Silurian and Devonian rocks to 

 erosion, the land surface above them was never reduced very 

 nearly to a plain. The lowlands, consisting of stream valleys 

 and seaward slopes, are the product of the earlier erosion cycles 

 plus the differential erosion of glacial and recent time. They 

 are best developed on the soft Carboniferous strata. 



* Ami, H. M., Trims. Nova Scotian Inst. Nat. Sci., i, new ser., pp. 185-192, 

 1892. Bull. Geol. Soc. America, xii. pp. 301-312, 1901. 



f Twenhofel, W. H., and Schuchert, Charles, this Journal (4), xxviii, pp. 

 143-169, 1909. 



% Fletcher, Hugh, Geol. Surv. Canada, II, p. 128P, 1887. 



§ Daly, R. A., Bull. Mus. Comp. Zoology Harvard University, xxxviii, 

 pp. 73-103, 1901. 



