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PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



[Dec. 19, 



elation of that great series of rocks which for our northern land was 

 first described by Sedgwick and Murchison, and since rendered clas- 

 sical in the literature of the age by the writings of Hugh Miller. 

 Though it is matter of doubt if any one of the species found in these 

 beds occurs in the system beneath, yet there are genera in common. 

 There are thus links binding them without a gap to the past stage 

 of life and its conditions. Still, in the abundance and variety of the 

 fish-remains, and in the introduction of new forms, as well as in the 

 tokens of a terrestrial surface, we feel that we have entered into a new 

 epoch and a new domain of created existence. There has been in 

 some minds a hesitation to accept these rocks as the basis of the 

 system ; but we think the evidence adduced is conclusive on this 

 point. 



Secondly, the review of the peculiar fauna and flora of these 

 lower beds of the Old Red Sandstone affirms the necessity of subdi- 

 viding the system into formations, and of assigning to the Forfarshire 

 flagstones (with their associated sandstones, cherty limestones, and 

 conglomerates) the place of the Lower formation in this extensive 

 group of strata. The thickness of our Forfarshire beds is enormous, 

 10,000 feet at least. In these rocks we have a facies of animal and 

 of vegetable lifo characteristic and distinct from that of the Upper 

 and Middle formations ; a subdivision is therefore demanded for 

 the purposes of classification. Between the Lower and Middle and 

 Upper beds of the system, there is a marked hiatus : for O&phalaspis 

 has never yet been found but in the Lower formation ; and when we 

 leave that, not only is Crustacean life at once and immensely dimi- 

 nished in its numbers, but its types are completely changed. 



From the recorded observations of Mr. Geikie, there seem to be 

 other areas, of great extent, in Scotland over which this Lower Old 

 Red Sandstone is known to spread ; and its area in England is very 

 considerable. We have thus all the elements of value in constituting 

 a formation in geological classification, namely superficial develop- 

 ment over extensive areas, great (we may say enormous) depth of 

 strata, considerable variety of mineral conditions (in conglomerates, 

 flagstones, sandstones, and cherty limestones), and a peculiar palaeon- 

 tology. 



Thirdly, we claim the right of the Old Red Sandstone as a whole 

 to be admitted and fully recognized as one of the great systems in 

 geology, both on the ground of what has been now advanced and 

 from all previously recorded knowledge of the Middle and Upper 

 formations. The series of rocks called the " Old Red Sandstone " is 

 as large as almost any of the well-marked and acknowledged divisions 

 into which, at the call of Science, the strata of the earth have been 

 made to fall. The system in Scotland alone covers an immense extent 

 of ground. There are large patches of it flanking the Silurian strata 

 in the south of Scotland — inBerwickshire, Roxburghshire, Lanarkshire, 

 and Ayrshire. There is the great development of it in the central 

 district of Scotland, comprehending all the lowland portions of Kin- 

 cardmeshire, Forfarshire, Perthshire, Stirling, and Dumbartonshire, 

 with many an offshoot into neighbouring counties. It stretches on 



