550 Remarks on the 



But Cuvier declares, and he is no mean authority in such matters, 

 " that these formations must have increased still more rapidly at first, 

 when the mountains furnished more materials to the rivers ;"• so that 

 we should in former times not only have had larger supplies of detritus, 

 but a less depth to deposit it on, and it is therefore obvious, that no great 

 lapse of ages would be required for the formation of our existing strata, 

 even if unsupported by the admitted fact, that the present order of things 

 cannot be older than about 4000 years. 



Nor can I see in the strata of the Delta anything to warrant the con- 

 clusion, that long periods of repose and action have been alternately 

 instrumental to the formation of those deposits, or that risings and 

 sinkings of the mass have occurred. Certainly the alternations of thick 

 beds of sand, with clays and calcareous seams can never authorise the 

 supposition, for we have examples in the coal formation of our native 

 land to shew us, that it is very possible for calcareous strata to alter- 

 nate with sandstones, and yet that they shall have been deposited in an 

 estuary, without the aid of repeated revolutions of salt and fresh 

 waters, as was once the current belief. 



On this head I need only refer to the magnificent work of Mr. 

 Murchison on the Silurian System, extracts from which have appeared 

 in this Journal. 



It is now found therefore, that the opinion which long prevailed 

 among geologists, that the occurrence of alternate beds of marine and 

 fresh-water strata, each imbedding its own peculiar exuviae, was proof 

 that long periods had elapsed during which the sea and fresh-waters al- 

 ternately prevailed, is no longer tenable, for it has been ably shewn by 

 one of the first authorities of the day, that such alternations prove 

 nothing more than the influx of some mighty river charged with 

 the produce of the land, into some estuary of the sea ; and consequent- 

 ly that while the Oceanic waters were depositing those limestones 

 which are termed marine, the rivers were depositing among them other 

 strata which are proper to fresh-waters ; thus they are proved to be 

 of contemporaneous origin although alternating, and a most important 

 blow is thus struck at the progressive system, for the animals of 

 the one formation which were supposed to indicate a period when they 

 alone were living, are found to be contemporaneous with the forms 

 peculiar to the other. 



Such enlightened researches as those of Mr. Murchison must happily 

 tend, ere long, to shake to their foundation the false and pernicious 



* Jameson's, Cuvier's Theory of the Earth. 



