MURCHISON ON THE SILURIAN SYSTEM. 1/5 



Salop (Shropshire), Montgomery, and Hereford, through those of 

 Radnor, Brecon, and Caermarthen, and having recognized an outcrop 

 of all the fossiliferous strata above-mentioned, as surmounted by the 

 Old Red Sandstone, I was urged by geologists at home and abroad 

 to give a distinct name to this whole series of fossiliferous beds. 

 Hence the word "Silurian," as propounded early in the year 1835 ; 

 the System, as I then termed it, being divided into Upper and Lower 

 groups*. 



Had I never published a single document beyond the memoirs 

 already mentioned, no one could have disputed my right in the world 

 of science to sustain a nomenclature and classification which was en- 

 tirely my own. I had, in short, propounded a natural system, which, 

 composed of four formations, each characterized by fossils and con- 

 nected by a general or common facies, had in many tracts a clear top, 

 and in one tract of my own region an unfossiliferous bottom (the 

 Longmynd). The same formations were subsequently (1836) shown 

 to exist in the sea cliffs of Pembrokeshire, and to be there also sur- 

 mounted by the Old Red Sandstone f. Unluckily, there lay to the 

 west of my Silurian country a vast slaty region terminating in the 

 highest mountains of North Wales, and of which I never attempted 

 to obtain an acquaintance, because it was entirely under the super- 

 vision of Professor Sedgwick, my colleague in former years. I took 

 it for granted on his showing, that all these harder slaty rocks were 

 really inferior to my softer schists and sandstones, or to quote his 

 own words, " it appeared to me absolutely certain that the greatest 

 portion of the undulating series of North Wales was inferior to the 

 lowest rocks of SiluriaJ." This was from the first his own view, 

 and I relied on it. 



In short, at the Dublin Meeting of the British Association, or some 

 months after I had published the first Silurian Tables, with lists of 

 their fossils. Professor Sedgwick and myself communicated respect- 

 ively our views. I gave a general sketch of the '' Silurian " rocks, 

 and he for the first time used the word ''Cambrian" in a geological 

 sense, and as defining a great group of slaty rocks lying beneath the 

 Silurian, but referring to no fossils §. 



On one occasion (in 1834) I crossed the assumed limit in the Ber- 

 wyn Chain, travelling by the high-road, in his company, to look for 

 a moment at the Bala limestone, which I then believed to plunge 

 under those true Llandeilo flags with Asaphus Buchii which I had 

 recognized on the east flank of that chain. This idea of the order of 

 infraposition has proved to be entirely erroneous, and if I " lost my 

 way " in going downwards into the region of my friend, it was under 

 his own guidance. I am answerable only for Silurian and Cambrian 

 rocks described and drawn as such ivithin my own region. 



Not seeing in that hurried visit any of the characteristic IJandeilo 

 Trilobites in the Bala limestone, I did not then (1834) identify that 



* See Philosophical Magazine, New Ser. vol. vii. p. 46 et seq. 



t Proceed. Geo]. Soc. vol. ii. p. 226. 



X Quart. Journ. Geol. Soc. vol. iii. p. 161. 



§ Report of the British Association, August 1835, Trans. Sections, p. 59. 



N 2 



