458 Sir H. H. Howorth — Geological History of the Baltic. 



Baklandet in Trondhjem, and his discovery was recorded by Sars in 

 1865. Here it was 12^^ metres above the sea. Kjerulf reported 

 similar finds at Klabu, Selbu, and Nidelven in the same province, 

 apparently up to 130 or 150 metres (ibid., 124-9). In [N'odland 

 and at Nidelven it was found by Rekstad. 



I have described the localities where the Yoldia iauna has occurred 

 in eonsidei'able detail because of the important place which it 

 has filled in geological polemics, and because for a long time the 

 deductions based upon it had to be supported by very limited 

 examples. It is now obvious that the fauna was widely spread 

 over the area once occupied by the Christiania Fjord, the northern 

 Cattegat, and the Eastern Gulf, which included the Great Lakes of 

 Sweden. 



Let us now turn to the lesson which these beds have to teach us 

 and which I claim have been completely misunderstood. There is no 

 question about Yoldia and its companions being very high Arctic 

 shells, nor is there any ambiguity in interpreting the evidence caused 

 by the mixture of shells occuriing in other beds or living under more 

 temperate conditions. It is perfectly plain that at the horizon 

 where these shells lived the temperature must have been very low. 

 This is indisputable. There are other facts, however, which preclude 

 the explanation of their surroundings offered by Brogger, and which 

 have led him and many others, including the late Professor James 

 Geikie, to postulate that when they were living Scandinavia must 

 have been under glacial conditions. I especially propose to deal 

 with Brogger's arguments. 



First, then, about the relative position of the Yoldia beds to the 

 later or Tapes beds, and especially in the Christiania Fjord where they 

 occur together. The Yoldia beds in this district do not occur higher 

 than from 40 to 50 metres or a little more above tho^ sea-level, while 

 the later beds in which the molluscs are virtually the same as those 

 now living in^the adjoining sea have been found by Mr. Oven at 

 Grefsen and Arvold, near Christiania, as high as 203 to 208 metres 

 (Brogger, op. cit., 693). I have given a series of other hf^ights 

 attained by them in this district in an earlier page. The Yoldia 

 clay, says Brogger, occurs at the height of 40 to 60 metres in some 

 places. At lower levels, he says, they occur at Nevlung, Laven, 

 Sandefjord, Tonsberg, Asgards Strand, Horlten Moss, and Bade, by 

 the Glommen, etc., on the present shore-line and only a few metres 

 above it. That is to say, in this district the Tapes beds lie far above 

 the Yoldia beds. Elsewhere the two sets of beds occupy the same 

 relative position towards each other wherever they occur together in 

 other parts of Scandinavia. It seems to me inevitable that this 

 involves the conclusion that the Tapes beds emerged from the sea 

 before the Yoldia beds. That is the conclusion Brogger has himself 

 drawn in the similar case of the Ancylus beds and the Litorina beds 

 of Sweden, and it cannot be evaded. 



It is also plain that the molluscs of the upper or Tapes beds, which 

 are rich in the number of species, are, with very slight and negligible 

 exceptions, all of the same forms as those now living in the 

 adjoining seas, while none of those in the Yoldia beds are now 



