512 MR. A. HARKER ON ROCKS 



§ V. Conclusion. 



Although the rocks of this district are so greatly disturbed, an 

 oxamination of the richly tbssiliferous deposits indicates beyond 

 doubt, in most cases, the original order of succession of the strata. 

 We find that, though in general the deposits are similar to those of 

 the adjoining Lake District, there are important variations in detail, 

 especially with regard to the Coniston Limestone group, and we feel 

 convinced that a study of this Cross Pell area is absolutely neces- 

 sary to the right understanding of the sequence of events which 

 marks the history of the Lower Paleozoic rocks of the North of 

 England. 



EXPLANATION OF PLATE XVII. 



Fig. 1. Map of the Cross Fell Inlier on the scale of one inch to a milec 

 Fig. 2. A portion of the same on the scale of two inches to a mile. 

 Fitf. 3. Section in Swindale Beck on the scale of six inches to a mile. 



APPENDIX I. — Peteological Notes on Pocks /rowi the Cross Fell 

 Inlier. By Alfred Harker, Esq., M.A., E.G.S., Fellow of 

 St. John's College, Cambridge. 



1. Skidd AW Slates. 



It will not be practicable here to deal with more than the leading 

 rock-types of a rather complex area. Further, as my own acquaint- 

 ance with the district is slight, and most of the specimens studied 

 were collected by Prof. Nicholson and Mr. Marr, these notes will 

 not aim at being more than merely descriptive, and must be 

 regarded as only supplementary to the field-work embodied in the 

 foregoing paper. 



The general character of the Skiddaw Slates is known from the 

 descriptions of numerous writers on the Lake District. In parti- 

 cular, the occurrence in the group of subsidiary volcanic rocks has 

 been indicated on the Geological Survey maps and in Mr. Clifton 

 Ward's Memoir. It will be sufiicient here to notice certain modifi- 

 cations of the slate-rocks due to metamorphic agencies, and to 

 describe two or three examples from the volcanic portions of the 

 group. 



The evidences of dynamo-metamorphism in the Skiddaw Slates 

 of Brownber, &c., have already been pointed out by Mr. Marr. 

 Judging from his specimens, the rocks thus modified still part along 

 the surfaces of original deposition, as marked out by alternations of 

 purely argillaceous and more gritty bands ; but on the wavy 



