GEOLOGY 221 



These show that the lower limestone is of Silurian age, about 

 the horizon of the Niagara. 



Similar conditions prevail in the cliffs at Beechey island, 

 where a large collection of fossils was obtained from the lower 

 limestone beds, while others, picked up loose, but evidently 

 fallen from the cliffs above showed that the upper beds passed 

 close to if not into the Devonian, as stated in Appendix IV. 



Similar Silurian limestones constitute the island of Corn- 

 wallis, to the westward of North Devon, while in the remaining 

 Parry islands farther west the Silurian strata are lost beneath 

 the Devonian and Carboniferous rocks of those islands. 



DEVONIAN. 



The work of the older geologists, which was summarized by 

 Haughton and later by Dawson, took no account of the Devon- 

 ian in their divisions of the Palaeozoic rocks of the islands north 

 of Lancaster sound. All the lower limestones were classed as 

 Silurian, while the overlying sandstones were placed in the 

 Carboniferous. Fossils of Devonian age were collected, by the 

 expedition of 1876, from the northern part of Ellesmere, but 

 their occurrence and relations were only finally settled by Schei 

 as given above. From his observations it is plain that the upper 

 part of the limestones and the lower 1,000 feet of the overlying 

 sandstones are of Devonian age. The early explorers were not 

 trained geologists, and it could hardly be expected that they 

 would discover the thin bands containing fossils in tjiese great 

 thicknesses of barren beds. Owing to this supposed lack of fos- 

 sils the rocks were separated into Silurian and Carboniferous 

 almost wholly on lithological differences, the limestones being 

 classed as Silurian and the sandstones as Carboniferous. 



There is no doubt that Devonian rocks are included in the 

 Carboniferous of the western Parry islands, but as they occur 

 only in the cliffs underlying the Carboniferous beds that cover 



