of the Older Stratified Rocks of Devonshire and Cornisoall. 259 



of the Silurian and Carboniferous Systems ; a fact which at 

 once defines their true place in the sequence of British rocks. 

 The hypothesis he seems most inclined to adopt is the fol- 

 lowing : — That the calcareous and slaty system of South 

 Devon is the newest, being above the carbonaceous system; 

 and that the carbonaceous system is newer than the grey- 

 wacke north of Barnstaple. In this way the calciferous band, 

 " extending from Torbay, &c., into South Cornwall, would 

 be in a higher part of the greyvvacke series, and might be 

 even equivalent to the beds known as the old red sandstone." 

 —{Report, &c. p. 149.) 



We agree with the concluding remark ; but not for the 

 reason hypothetically stated, viz. : that South Devon is in a 

 higher part of the greywacke series ; for we place the North 

 and South Devon groups on the same parallel, and consider 

 the culm-measures as unequivocally superior to them both. 



So long as we were unprovided with a typical suite of fossils 

 from the older system of Devon, it was impossible to propose 

 for it any name ; but now, having discovered a great many of 

 its fossils, and that too in regions wherein the red arenaceous 

 character gives way to the slaty impress, and a very different 

 mineral aspect; the necessity of adopting a new name becomes 

 apparent, and we propose the term " Devonian System" as 

 that of all the great intermediate deposits between the Silurian 

 and Carboniferous Systems. The " Devonian System" is 

 so far unexceptionable, that it may be applied, without any 

 contradiction of terms, to rocks of every variety of mineral 

 structure which contain the characteristic series of organic 

 remams. 



When these organic remains are described, we shall then 

 have a regular descending order of the older fossiliferous 

 strata in the three great lower systems which pass into each 

 other, the Carboniferous, Devonian, and Silurian. Whether 

 the still lower slaty rocks to which one of us applied the term 

 Cambrian, may or may not contain, in their inferior parts, 

 distinct tvpical fossils, is a problem not yet solved, though as 

 far as our labours have gone, we know that many of the shells 

 which characterize the lower Silurian group, exist also (even 

 at considerable depths) in the great upper Cambrian group, 

 and tlierefore the line we have provisionally drawn between 

 the Silurian and Cambrian Systems may, eventually, be fixed 

 by some natural grouping of fossils at a different level. 



We proposed the use of the terms Silurian and Cambrian be- 

 causewe believed that their adoption, (L. & E. Phil. Mag., vol. 

 vii, pp. 4G, 483,) when applied to well-defined mineral masses, 

 might tend to clear away the obscurity which we were per- 



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