Frof. G. Linnarsson — The Oldest Rocks of N. Europe. 147 



Eophyton Sandstone of Westrogothia. In the Upper Silurian Sand- 

 stones of Gotland I have found markings quite similar to some forms 

 of Cruziana occurring in the Eophyton Sandstone. Even the Eophyton 

 itself occurs at several horizons.^ The other fossils of the Eophyton 

 Sandstone, especially a Brachiopod, which is not rare in its lowest 

 beds, might be identified with more certainty, but I do not know from 

 foreign countries any species which can be suspected to be identical 

 with them, and even their generical relations are not quite settled. 

 The Brachiopod above referred to — ^I have provisionally termed it 

 Lingula or Obolus monilifer — should in all probability form a peculiar 

 genus, judging from the structure of the shell substance. Hyolithus 

 lavigatus and Astylospongia radiata have, as far as I know, no near 

 relatives. Thus the palseontological facts alone do not yet make a 

 parallelism possible between the Cambrian Sandstones of Scan- 

 dinavia and the rocks of other countries ; but, all things considered, 

 I can find no reason for believing these Scandinavian Sandstones to 

 be younger than the oldest English Cambrian rocks, with which 

 they agree in position. The comparatively small thickness of the 

 Swedish Sandstones cannot be considered as an evidence of their 

 belonging to a later and more circumscribed period than the chief 

 masses of the British Longmynd rocks (those without Trilobites); 

 then it is a well-known fact that the Cambrian and Silurian beds of 

 Sweden are in general much thinner than their British equivalents. 

 Thus, for instance, the Olenus Schists of Sweden in most places 

 hardly exceed 40 or 50 feet in thickness, nevertheless they 

 contain equivalents of all the divisions of the British Lingula 

 flags, which are stated to exceed 4000 feet. This proves that at the 

 Olenus period the sediment was accumulated about one hundred times 

 faster in the British area than in the Swedish. It is very probable 

 that even in the oldest portions of the Cambrian era a similar, if 

 not quite so great a disparity occurred in the rate at which the 

 sediment was accumulated in both areas. The thickness of the 

 Cambrian Sandstones of Scandinavia is very variable. In the 

 middle of Sweden it seems to be about 100 feet ; in the north and 

 south it is probably more considerable. In some Norwegian districts 

 the Cambrian Sandstones are calculated by Professor Kjerulf ^ to 

 exceed 2000 feet in thickness, but in others, as near Christiania, they 

 are only thin. In Britain the rocks lying beneath the lowest beds 

 containing Trilobites are supposed to be about 1500 or 1600 feet in 

 thickness, which is fifteen times that of the Scandinavian Sandstones, 

 where they are thinnest. Even if the superiority in the rate of the 

 sediment forming is supposed during the oldest Cambrian period to 

 have been only one-sixth of that during the period of the Lingula flags, 

 it is not, therefore, from stratigraphical reasons, necessary to consider 

 the lowest Longmynd rocks of Britain to be older than the oldest 

 Cambrian Sandstones of Sweden. Still less do the stratigraphical 

 evidences support the opinion that the Longmynd rocks represent 

 a more remote time than the Cambrian Sandst(mes of Norway. 



^ Cf. Zeitsclirift der Deutschen geologischen Gesellschaft, 1875, p. 245. 

 2 Sparagmitfjeldet. Cliristiana, 1873. 



