VARIETY OF STRATA NOW FORMING. 335 



there will arise a stratum far to the west which, though oc- 

 cupying the same position relatively to other beds, formed 

 of like materials, and containing like fossils, will yet be per 

 haps a million years later in date. 



But the illegitimacy, or at any rate the great doubtful- 

 ness, of many current geological inferences, is best seen 

 when we contemplate terrestrial changes now going on : 

 and ask how far such inferences are countenanced by them. 

 If we carry out rigorously the modern method of interpret- 

 ing geological phenomena, which Sir Charles Lyell has done 

 so much to establish — that of referring them to causes like 

 those at present in action — we cannot fail to see how im- 

 probable are sundry of the received conclusions. 



Along each line of shore that is being worn away by 

 the waves, there are being formed mud, sand, and pebbles. 

 This detritus, spread over the neighbouring sea-bottom, 

 has, in each locality, a more or less special character ; de- 

 termined by the nature of the strata destroyed. In the 

 English Channel it is not the same as in the Irish Channel ; 

 on the east coast of Ireland it is not the same as on the 

 west coast; and so throughout. At the mouth of each 

 great river, there is being deposited sediment differing 

 more or less from that of other rivers in colour and quali- 

 ty ; forming strata that are here red, there yellow, and 

 elsewhere brown, grey, or dirty white. Besides which va- 

 rious formations, going on in deltas and along shores, there 

 are some much wider and still more contrasted formations. 

 At the bottom of the ^goean Sea, there is accumulating 

 a bed of Pteropod shells, which will eventually, no doubt, 

 become a calcareous rock. For some hundreds of thou- 

 sands of square miles, the ocean-bed between Great Britain 

 and North America, is being covered with a stratum of 

 chalk ; and over large areas in the Pacific, there are going 

 »n deposits of coralline hmestone. Thus, throughout the 



