On the Lower Silurian Rucks of Cumberland. 401 



and to suggest that the Harrogate roadstone probably corresponds 

 to the Main, or 12 fathom, limestone at the top of the Yoredale 

 series. These results, the arguments and facts in support of them, 

 and the inferences obtainable from their consideration were given 

 by the author in this paper, which was illustrated by a horizontal 

 section from Wharfe, on the S.E., through Harrogate, to Nid on the 

 N.W. 



February 22, 1865. — W. J. Hamilton, Esq., President, in the Chair. 



The following communications were read : — 



1. " On the Lower Silurian Rocks of the South-East of Cumber- 

 land and the North-East of Westmoreland." By Professor R. 

 Harkness, F.R.S., F.G.S. 



The district described in this paper consists of a narrow band of 

 country on the western side of the Pennine Chain ; it possesses 

 external features which indicate a geological structure different from 

 that of the Pennine escarpment, and from that of the adjacent 

 country on the west, from which it is separated by the Pennine 

 fault. Prof. Harkness described the Lower Silurian rocks occupy- 

 ing this narrow tract in some detail, and showed them to consist of 

 Skiddaw Slates, with interstratified greenstone porphyry and ash, 

 and a band of fossiliferous shale. He also gave, in illustration of 

 the structure of the country, a section from Melmerley Scar to 

 Pkomanfell, and one from Milburn to Dunfell, together with a geolo- 

 gical sketch-map of the narrow Lower Silurian tract in question. 

 In conclusion the author described a fault which brings the Skid- 

 daw Slates against the Coniston Limestone, and another, which 

 cuts through the Lower Silurian rocks of the district, having a 

 course at right angles to the former, and nearly parallel to that of 

 the Great Pennine fault. 



2. " Note on the Volcanic Tufa of Latacunga, at the foot of Coto- 

 paxi ; and on the Cangaua, or Volcanic Mud, of the Quitenian 

 Andes." By R. Spruce, Esq. 



The Volcanic Tufa described in this paper is not only used for 

 building-purposes, but also by the smiths instead of charcoal, as 

 when heated to redness it emits considerable heat, but very little 

 flame. The author then described the large deposits of Volcanic 

 Mud, called Cangaua, which are met with throughout the central 

 valley of the Quitenian Andes. This mud is compact, slightly 

 argillaceous, and more or less saline, and occurs in rock-like masses, 

 yielding very slowly to atmospheric agency, or even to running 

 water. 



3. " On the Discovery of Flint Implements in the Drift at Milford 

 Hill, Salisbury." By Dr. H. P. Blackmore. 



Since the discovery of Flint Implements in the Higher-level 

 gravel at Fisherton on the west of Salisbury, a large number of 

 very excellent weapons have been obtained from the Drift-gravel of 

 Milford Hill. This deposit is of the same age as the Fisherton 

 beds ; but it is situated on the opposite side of the Avon, imme- 

 diately to the east of Salisbury. 



