193 



the most likely. A general survey of the district lies behind 

 us ; we now come to the point when detailed stratigraphie ob- 

 servations should be made. For those who will in the future 

 devote themselves to this work it will probably be an advantage 

 to set out from the view presented here as a working hypothesis. 



Perhaps the most interesting feature about the sedimentary 

 rocks of the district is the very considerable dissimilarity in 

 appearance between the older, pre-Jurassic and the more recent 

 rocks. This is most marked in the occurrence of huge, inten- 

 sively red strata in the former series, but also in its scarcity 

 of fossil remains and the common occurrence of limestones 

 iprobably dolomitic); possibly also in the character of the in- 

 cluded conglomerates. 



For the present I can ofîer no satisfactory explanation of 

 these decided differences and the subject is too specialistic for 

 me to enter into it here. It does not seem as if it were bound 

 up with a formation of the rocks at different depths of the sea 

 during different periods. As to the red colour, its presence in 

 the older strata could be attributed to the formation of latérite 

 in the polar areas only being able to take place during these 

 periods. It would be interesting if something of the sort could 

 be proved, but the conditions seem to point rather to the cause 

 of the differences being of a more local nature. 



What is said here applies, of course, in the first place 

 only to the strata whose age has been determined with cer- 

 tainty. Yet it seems to me that there is no great doubt 

 that the non-fossiliferous series here described, those at least 

 examined by me, really belong in any case to the main division 

 in which I have placed them. As to their reciprocal ages, I 

 refer to the detailed account. 



As far as the stratigraphie conditions are concerned, it is 



difficult to be more precise about the area N. of Davy Sund. 



Nathorst himself lays stress on the possible occurrence at 



Traill I. of more recent (and perhaps also older) strata than 



XXVIII. 13 



