./. IK Dana — Sedgwtok and Murchison. L78 



Mr. Warburton of any intentional injustice — qnite the con- 

 trary; for I know that he gave bis best efforts to the abstract. 

 Bat he had undertaken a task for which he was not prepared, 



inasmuch as he had never well studied any scries of rocks like 

 those described in my papers." Sedgwick here nsee Protozoic 

 in the Sedgwick sense, not, as above in the Morchison sense. 



I g wick again in 1854, speaks of "the tampering with the 

 names o\' my reduced map." But these explanations of his 

 should take the harshness out of the sentence, as it was in 1843 

 to L846 out of all his words. 



The paper has further interest in its long lists of fossils in 

 two tables: I, "Fossils of the Older Palaeozoic (Protozoic) 

 Rockfi in North Wales, by J. W, Salter and J. de 0. Sowerhv/' 

 showing their distribution; and II, "Fossils of the Denbigh 

 flagstone and sandstone series/' 



Thus, until 18-±r>, no serious divergence of views had been 

 noted by Sedgwick. This is manifested in his paper on the 

 Slate rocks of Cumberland, read before the Geological Society 

 on the 7th and 21st of January, 1846,* which says, on the last 

 page but one: "Taking the whole view of the case, therefore, 

 as I know it, I would divide the older Palaeozoic rocks of our 

 island into three great groups : 3d, the upper group, exclu- 

 sively lj>/>r/' Silurian ; 2, the middle group, or Lower Silw- 

 rian^ including Llandeilo, Caradoc, and perhaps Wenlock ; 1, 

 the first group, or Cambrian;" differing in this arrangement 

 from Murchison only in the suggestion about the Wenlock. 

 The italics are his own. He adds : 



" This arrangement does no violence to the Silurian system of 

 Sir R. Murchison, but takes it up in its true place; and I think 

 it enables us to classify the old rocks in such a way as to satisfy 

 the conditions both of the fossil and physical as well as mineral- 

 ogical development." 



But before the year 1846 closed not only the overlapping 

 of their work was recognized but also the consequences ahead, 

 and divergence of opinion began. 



In December a paper was presented by Sedgwick to the 

 Geological Society on "the Fossiliferous Slates of North 

 Wales, Cumberland, Westmoreland and Lancashire,"f which 

 contains a protest against the downward extension of the Silu- 

 rian so as to include the Cambrian. It is excellent in spirit 

 and fair in argument. Many new facts are given respecting 

 sections of the rocks in South Wales and North Wales, in some 

 of whicli occur the Lingnla flags, and characteristic fossils are 

 mentioned. In describing some South Wales sections, Sedg- 



* Q. J. Geol. Soc, ii, 106, 122, 1846. f Ibid., iii, 133, Dec, 1846. 



