206 Hughes— Silurian Rocks of Casterton Low Fell. 



V. — Note on the Silurian Eocks of Casteuton Low Fell, 

 KiKKBT Lonsdale, Westmokeland. 



By Thomas McKenny Hughes, B.A., F.G.S. 



I SHOULD not have presumed to publish, an opinion as to the 

 geological position of the rocks of Casterton Low Fell without 

 having examined the typical region of Coniston and Windermere, 

 had not Mr. Woodward thought it desirable to notice the occurrence 

 there of a species of Ceratiocaris and asked me to furnish him 

 with a note on the bed from which I obtained it. Having therefore 

 collected all the evidence I could in that limited and complicated 

 area, I now, with the permission of the Director of the Survey, send 

 him some extracts from my notes, which may be of interest, as 

 showing the character and relations of the rocks there seen. 



The Silurian Eocks of Casterton Low Fell, and Barbon Low Fell, 

 are bounded on the West and South by a great fault which brings 

 various parts of the Old Eed, Carboniferous, and Permian, against 

 the Silurian Eocks. This may well be seen in Barbon Beck, near 

 the church ; where the Old Eed is faulted against the Carboniferous 

 Limestone, and this again, in less than fifty yards, is faulted against 

 the Silurian Eocks. The faidt runs in a southerly direction bending 

 round to the S.S.W. by Whelprigg, where the Old Eed Conglomerate 

 is seen, not in contact with the Silurian, but very close by it. From 

 this point the boundary is entirely obscured by drift till we come to 

 Leek Beck where the Permian beds are thrown against the Silurian. 

 Here again they are not seen in contact, but they occur near one 

 another in such a manner that we cannot explain the phenomena by 

 the unconformity of the Permian on the Silurian. On the East and 

 South East of this the ground is entirely covered by drift, but pro- 

 ceeding up the stream to BuUpot we soon find evidence of a great 

 double fault, like that seen on the other side of the hill in Barbon 

 Beck, running North and South, and bringing the Yoredale Eocks 

 against the Mountain Limestone, and that in a few yards more 

 agaiast the Silurian. These two sets of faults are connected by a 

 series of transverse faults, running nearly W.N.W. and E.S.E. on the 

 South side of Barbon Beck. Thus it will be seen that the Silurian 

 rocks of the area under notice are cut ofi" all round by enormous 

 faults, and therefore that their age must be determined by the evi- 

 dence we can obtain within that area, I have frequently searched 

 for fossils ia company with Mr. Gibbs, Fossil Collector to the Survey, 

 and also with Mr. Hindson, and Mr. Haythornthwaite of Kirkby 

 Lonsdale, but the number, both of species and of individuals, that 

 we were able to obtain, was small. 



The accompanying section is drawn from the Permian beds in 

 Leek Beck, due North, to beyond the second of the set of faults on 

 the North slope of Barbon Low Fell, about a quarter of a mile Soiith 

 of Barbon Beck. 



The first beds seen are dark grey coarse flags ; the dip is at first 

 irregular, but afterwards tolerably steady in a North- Westerly direc- 

 ^on at from 20° to 30°, and thip dip prevail^ with small minor 



