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THE GEOLOGIST. 



remains ; it was impossible to ascertain all the conditions which in- 

 volved the appearance of any particular form of life ; and we never have 

 risen, nor can rise, to such laws. With respect to the identification of 

 strata in distant countries by organic remains, in the absence of direct 

 evidence, he considered this evidence was as strong as we could expect 

 to obtain ; having proved its correctness in this country, we applied it 

 to more distant tracts. Assuming, in the first instance, a coincidence 

 between the conditions and organic types of our own country and that 

 which we examine, if in this investigation we meet with nothing contra- 

 dictory, we extend the value of our inductive process. Amongst the 

 lower rocks of that part of America described, there was a carboniferous 

 and pentremite limestone, an intermediate group, and a Silurian group, 

 all bearing a remarkable analogy to those of our own country. The 

 series, as a whole, was more calcareous and, therefore, we might not 

 expect the same tranchant diflferences which the alternation of masses 

 of shale and sandstone had produced with us. An illustration of these 

 local differences occurred in the interpolation of the calcareous beds, of 

 which the crumbling colleges of Oxford were built, between the Oxford 

 and Kimmeridge clays of the south of England. At Cambridge, these 

 clays formed one uninterrupted deposit of mud, 2,000 feet thick. In 

 England all the work was done ; the long tiresome narrative like an 

 old chronicle full of enormous detail— like a book, too, some of the 

 leaves were torn out, and others so defaced that no mortal man could 

 read them. To supply this, we looked to other countries ; and, believ- 

 ing that nature has no starts, or blanks, seek to supply the deficiencies 

 in our own series, by an examination of those of other countries. In 

 reference to the economical importance of the district which formed the 

 subject of the memoir, Mr. Sedgwick remarked, that this country pos- 

 sessed inexhaustible mineral treasures, and the finest inland navigation 

 in the world, and pictured the influence it might be expected to exert, 

 in the coming period of time, its effect on the fortunes of the civilized 

 world, when all the intellect of the most active and energetic men on 

 that part of the earth should be brought to bear on these treasures ; and 

 he rejoiced that men, with Enghsh feeling and Enghsh blood, should 

 be bringing them into operation. 



Sir H. T. De La Beche remarked, that the principal groups of strata 

 were separable all over the globe, and the physical conditions which 

 produced those deposits and governed the changes of organic hfe must 

 have been the same over large portions of the globe also ; he assumed 

 a similarity of condition, not perfect identity; those deposits were 



