52 PICTURESQUE SKETCHES 



CHAPTER IV. 



THE INTRODUCTION OF FISHES, THE CHARACTERISTIC ANIMALS OF 

 THE SECOND FOSSILIFEROUS PERIOD. THE DEVONIAN OR OLD 

 RED SANDSTONE SYSTEM OF FORMATIONS. 



IT would seem that, during the whole period of the 

 deposit of those many thousand feet of strata which 

 make up the silurian series in Wales, Cumberland, 

 and other parts of the world, there was no contem- 

 poraneous formation going on in the district now oc- 

 cupied by Scotland, or in that which at present forms 

 the south-western counties of Cornwall and Devon- 

 shire in England. Further south, however, the silu- 

 rian rocks are met with again, as in Brittany ; and, as 

 I have already mentioned, they exist in great abund- 

 ance in various parts of Scandinavia, but owing to 

 some cause, probably because those portions of the 

 earth were then elevated above the level of the sea, 

 and so were not capable of receiving any extensive 

 additions, there does not appear to be in the British 

 islands any regular and complete passage from the 

 slates and sandy beds of the older and non-fossili- 

 ferous period, to similar deposits immediately resting 

 upon them. In Belgium, Russia, and Germany, such 

 a continuity may be traced. 



The existence of a break in the continuity of strata 

 occurring thus early, and extending over an important 

 geological period, but evidently local and confined to a 

 small district, is a phenomenon well worthy of remark, 



