PEOCEEDINGS OF THE SCIENTinO SOCIETIES OE LONDON. 287 



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

 ing tins 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 

 Bomanfell, 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 Grreat Pennine fault. 



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

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

 Andes." By E. Spruce, Esq. Communicated by Sir E,. I. Murchi- 

 son, K.C.B., F.E.S. — 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 Mil- 

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

 by John Evans, Esq., E.E.S., F.Gr.S.— 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 oppo- 

 site side of the Avon, immediately to the east of Salisbury. 



Dr. Blackmore described the materials composing the gravel 

 of Milford Hill, and discussed the nature and power of the forces 

 which had brought them together. He then described the position, 

 thickness, and physical relations of the deposit, stating that the 

 gravel is from 10 to 12 feet thick on the top of the hill, becoming 

 thinner and gradually dying away on the sides. The hill itself is 

 quite isolated, being separated from the surrounding higher land by 

 river-valleys ; its highest point is about 100 feet above the present 

 level of the riAers. 



