Geology and Geography. 409 



Section C. — Geology and Geography. 



Professor Jameson in the Chair. 



Lieutenant Murphy exhibited some sheets of the Ordnance Sur- 

 vey Maps of Ireland. 



Mr Nicol read a paper on the structure of recent and fossil woods, 

 in which he described the general results of his investigations. He 

 exhibited an extensive series of specimens illustrative of his obser- 

 vations, and explained his method of obtaining thin sections of re- 

 cent and fossil woods. 



Professor Traill communicated some remarks on the geology of 

 the Orkneys. These islands consist chiefly of sandstone, and of a 

 sandstone flag much charged with clay, belonging to the old red 

 sandstone. Granite also occurs very like that of Sutherland, close 

 grained, and often approaching to gneiss ; and is covered by a con- 

 glomerate. The fossil fishes occur near Skaill in Pomona, about 

 two miles from the junction of the granite with the slate. 



Mr Murchison spoke of the fossil fishes of Caithness, and said he 

 had formerly sent specimens to Cuvier, who had been disposed to 

 refer the families to which they belong to those of Mansfield and 

 the Thiiringerwald. Mr Murchison afterwards visited the spot with 

 Professor Sedgwick, and came to the conclusion, that the strata 

 containing the fishes are referable to a formation as old as the old 

 red sandstone, and perhaps ascending as high as the carboniferous 

 series. 



Professor Sedgwick entered at considerable detail into the nature 

 of the sandstone deposits of the north of Scotland. 



Dr Hibbert considers the fossil fishes in question as belonging to 

 a formation analogous to that of Mansfeld. 



M. Agassiz expressed his opinion t hat the fossil fishes of Orkney 

 and Caithness belong to a period more ancient than the coal mea- 

 sures. 



Mr Lyell agreed with Professor Sedgwick and Mr Murchison in 

 their opinions, and made some remarks on the geology of Forfar- 

 shire. 



Mr Milne read a paper on the geology of Berwickshire, and de- 

 scribed the different fonnations of which that district consists, viz. 

 the greywacke, old red sandstone, coal measures, and trap. He 

 detailed the mineralogical and fossil characters, marking their dif- 

 ferent formations, and in particular alluded to the question as to 



