1869.] HULL— GEOLOGY OE CHESHIRE. 171 



In constructing some of the railways of South America the gra- 

 nite was found to be so soft, from decomposition, that it could be 

 cut with the pick and spade ; and this softened granite, when washed, 

 produced gold. 



Prof. T. Rupert Jones considered that, by means of Dr. Suther- 

 land's communication, the Laurentian and Silurian rocks were now, 

 for the first time, to be recognized as existing beneath the Dicynodon- 

 rocks of the Natal ridge. 



Febrttary 10th, 1869. 



Moreshwar A'tmarani Tackhadakar, Esq., 3 St. George's Square, 

 Primrose Hill, N.W., and Henry Spicer, Jun., Esq., 22, Highbury 

 Crescent, N., were elected Fellows of the Society. 



The following communications were read : — 



1. On the Evidences of a Ridge o/ Lower Carronifehotjs Rocks cross- 

 ing the Plain of Cheshire beneath the Trias, and forming the 

 boundary betvjeen the Permian Rocks of the Lancashire Type on 

 the North, and those of the Salopian Type on the South*. By 

 Edward Hull, Esq. M.A., F.R.S., District Surveyor of the Geolo- 

 gical Survey of Scotland. 



It has generally been supposed that the Triassic plain of Cheshire, 

 almost encircled as it is by coal-fields, is itself a great repository of 

 coal-bearing strata having few or no interruptions to its continuity, 

 except towards the southern margin, where the Triassic and Permian 

 rocks, overlying at intervals thin and marginal representatives of 

 the coal-measures, approach the Cambrian and Silurian districts of 

 Shropshire. I myself for a long while held and defended this view ; 

 nor was I aware until recently that it had ever been controverted. 

 I am informed, however, by Mr. Jukes, that in a discourse which he 

 delivered before the British Association in Birmingham, " On the 

 Position and Extent of Coal-measures beneath the Red Rocks of the 

 Midland Counties," in 1865, he expressed his opinion of the proba- 

 bility of ridges or bosses of rocks older than the coal-measures 

 underlying the Trias of the plain of Cheshire and Salop, and 

 throwing the Upper Carboniferous beds into detached coal-fields. 

 These views were illustrated by large diagrammatic sections ; unfor- 

 tunately no report of this lecture is published in the Transactions of 

 the Association. 



"With my own mind fully imbued with the idea of a continuous 

 sheet of coal-measures stretching beneath the New Red Marl from the 

 southern margin of the Lancashire coal-field as far south, at least, as 

 the Lias of Frees, near Whitchurch f, I last winter (1867) was 



* Communicated with the consent of the Director G-eneral. 



t In this direction the old rocks which formed the original margin of the 

 Carboniferous basin may be expected to occur in promontories projecting north- 

 wards under the Trias and Permian beds. (See Map, p. 183.) 



