COMPOSITION AND ARRANGEMENT. 133 



olden sea-shore ! the ripple of the receding tide, the wind- 

 ing trail of the shell-fish, the burrow and sand-cast of the 

 sea-worm, the patter of crustacean feet, the pittings of the 

 rain-shower, and the irregular shrinkage cracks of the sun- 

 baked shore-mud. And yet, as surely as these phenomena 

 are witnessed on the muds of existing sea-creeks, so surely 

 were they impressed on the shores of the Old Red Sand- 

 stone, were dried and hardened by the sun, covered over by 

 newer sediments, and thus preserved through all time as 

 evidences that nature's operations have been going forward 

 much in the same way from the remotest of periods. But 

 clear as these physical evidences are of the nature of the 

 Old Red sea-shore, there are facts connected with the great 

 extent and thickness of the pebbly (we may say bouldery) 

 conglomerates that are not so easy of explanation. We 

 know that in many parts of the world there are vast peb- 

 bly and shingly beaches, and that in some instances the 

 rounded blocks are hundreds of pounds in weight; but 

 there is something so peculiar in the aggregation of the Old 

 Red conglomerates, with their striated pebbles, their irre- 

 gular imbeddings of fine-grained sandstones and the like, 

 that they suggest the idea of masses floated and packed up 

 by shore-ice, and perhaps to some such condition their enor- 

 mous accumulations may yet be ascribed.* Be this as it 



* Several years ago we appended the following note to a chapter on 

 the Old Red Sandstone (' Past and Present Life of the Globe'), and see 

 no reason yet to change our opinion : Whoever has examined the boul- 

 dery conglomerates of the Scottish Old Bed, with their large irregular 

 blocks, their peculiar unassorted aggregation, the nature of the cement- 

 ing matrix, and the frequent " nestings " or interlaminated patches of 

 fine argillaceous sandstone, must have had suggested to his mind the 

 idea of ice-action. And this notion must have been strengthened when 

 he turned to the sandstones, and found them imbedding angular frag- 

 ments of rock, shale, and even clay, which could scarcely have suffered 

 transport unless enclosed in drifting ice-floes. The paucity of terrestrial 

 life in certain areas seems also a further corroboration of the idea of 

 glacial influences a hypothesis which seems at first sight extremely 



