134 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Dec. 17' 



affinity between the rocks of these areas. There is, however, in the 

 former, so far as we yet know, an absence of the genus Hast rites, 

 which is well represented in the south of Scotland ; but we miss in 

 the Scotch deposits the genera Diehograpsus and Tetragrapsus, which 

 make their appearance in the Skiddaw slates. But with reference to 

 the fossils from this series, their nature and the evidence they afford 

 as to age are discussed in a note which Mr. Salter has kindly added 

 to this memoir. 



If we take into consideration the direction of the strike of the 

 strata in the north of England and in the south of Scotland, we 

 find in this a great conformity, the prevalent strike in both countries 

 being W.S.W. and E.N.E. ; and, with reference to the dips, the di- 

 rection generally obtaining north of the Border is N.N.W., while to 

 the south thereof the most common inclinations are S.S.E. The 

 physical geology of the older rocks of the north of England and 

 south of Scotland supports the conclusion that the disturbing forces 

 which acted upon them operated in both areas at the same geolo- 

 gical epoch ; and also, judging from the arrangement of the meta- 

 morphic rocks of the Highlands proper, that the strata of the north 

 of Scotland owe their elevation to the same period. 



The general arrangement of the older rocks of the north-west of 

 England shows that not only have the Lower Silurians been sub- 

 jected to elevations producing a W.S.W. and E.N.E. strike, but also 

 that the succeeding Coniston limestone, Coniston flags, Coniston grits, 

 Ireleth flags, and Kendal group of Professor Sedgwick — deposits occu- 

 pying the horizons of the Caradoc, the Llandovery, the Wenlock, and 

 the Ludlow series of Sir R. I. Murchison — were elevated at the same 

 time as the older Silurian deposits. 



In Cumberland and Westmoreland, the older palaeozoic rocks are 

 succeeded unconformably either by the Upper Old Red Sandstones or 

 by the Carboniferous strata, both of which have strikes totally at 

 variance with the older rocks ; and consequently we are led to infer 

 from this evidence that the elevations of the Silurian series, both in 

 the northern and southern Highlands of Scotland and in the north 

 of England, took place during the earlier portion of the Old Red 

 Sandstone epoch. 



Denudation has removed from the northern Highlands probably 

 all the Upper Silurians (the metamorphic character of most of these 

 rocks does not allow of their being assigned to very definite Silurian 

 zones), and in the southern Highlands nothing remains of the older 

 palaeozoic rocks except the Lower Silurian series. In that portion 

 of the north of England which most nearly approximates to the 

 Silurian area of the south of Scotland, we have also only the lower 

 members of this series represented, while further to the south, denu- 

 dation not being so powerful, the whole of the Upper Silurian rocks 

 occur. 



The eastern edge of the older palaeozoic rocks of Cumberland and 

 Westmoreland had suffered a considerable amount of denudation 

 antecedent to the deposition of the Upper Old Red series, for, in these 

 latter, fragments of Skiddaw slates are, in some localities, very abun- 



