72 The Lowt:r Devoxian Deposits of Maryland 



manifest, that the rocks now under consideration, were the immediate and 

 natural precursors of the coal era, and stood therefore in the place of the 

 Old Eed Sandstone of other regions. The highly important deduction, 

 however, of Mr. Lonsdale, that the fossils of the South Devon limestones, 

 as collected by Mr. Austen and others, really exhibited a character inter- 

 mediate between those of the Silurian system and of the carboniferous 

 limestone, M-as the most cogent reason which induced Professor Sedgwick 

 and myself (after identifying North and South Devon) to propose the 

 term Devonian.^ The inference that the stratified rocks of Devonshire 

 and Cornwall, though of such varied composition, are really the equiva- 

 lents of the Old Eed Sandstone in the regions alluded to, has since, indeed, 

 been amply supported and extended by the researches of Sir Henry De la 

 Beche, Professor Phillips, and many other good geologists." ^ 



Murchison and Sedgwick further state : " The most instructive of the 

 sections published by my colleague and myself to illustrate the general 

 structure of Devonshire, is that of which the diagram in page 256 is a com- 

 piled reduction. It is a section across North Devon from the Foreland on 

 the British Channel, to the granitic ridge of Dartmoor on the south, and 

 exhibits a copious succession of the Devonian rocks between Linton and 

 Ilfracombe on the north, and Barnstaple on the south; the whole dipping 

 under strata of the carboniferous age, on the opposite side of a wide 

 trough of which, or on the north flank of Dartmoor, the Upper Devonian 

 strata again rise to the surface. 



" North Devon has thus been selected as affording, on the whole, the 

 best type of succession of the rocks to which the name Devonian was ap- 

 plied ; because it offers a clear ascending section through several thousand 

 feet of varied strata, until we reach other overlying rocks, which are 

 undeniably the bottom beds of the true carboniferous group.'' 



These great English masters of geology soon realized that to unravel the 

 North Devon sequence presented great difficulties, and they therefore 



' See Reports of Brit. Assoc, for the Advancement of Science, 1836, Bristol 

 meeting. Sedgwick and Murchison, Trans. Geol. Soc. London, vol. v, p. 633, 

 and Phil. Mag., vol. xi, p. 311. Lonsdale, Trans. Geol. Soc. London, vol. v, p. 721. 



^ See Report on the Geology of Cornwall, Devon, and W. Somerset, by De la 

 Beche, 1839, and the Palaeozoic fossils of the same region, by Professor Phillips, 

 1841. 



