86 Lower Silurian Rocks, Scotland. 



so many noble Fiords between Sleat and Cape Wrath, 

 while on the east there are large tracts of Old Red 

 Sandstone, more or less extending from Thurso in 

 Caithness to the Great Glen, Moray Firth, the river 

 Spey, and yet further east. Fig. 55, p. 287. 



In times within the memory of the writer, all these 

 metamorphic rocks of the Highlands were classed in 

 Wernerian style as Primitive strata, thrown down in 

 hot seas before the creation of life in the world. The 

 progress of research showed that gneiss and other rocks 

 now called metamorphic, are of many geological ages ; 

 and the fortunate discovery of fossils in these strata, at 

 Durness, by Mr. C. Peach, in 1854, showed them to be 

 of Arenig age, a discovery the importance of which 

 was at once seen by Sir Roderick Murchison, who by 

 this means, revolutionised the geology of the greater 

 part of the northern half of Scotland. Feeling anxious 

 to have a second opinion respecting the justness of his 

 new views, he asked me to accompany him on a long 

 tour through the northern Highlands in 1859, when I 

 mapped part of the country at Durness and Loch Eriboll, 

 and the whole matter seemed to me so plain, that the 

 wonder is, that any man with eyes ever dreamed of dis- 

 puting it. In these days no one now thinks of denying 

 the Lower Silurian age of the chief part of the gneissic 

 rocks of Scotland, the features of which have been 

 mapped by Professor Geikie, first in concert with Sir 

 Roderick Murchison, and afterwards personally in more 

 detail. 1 



With regard to the physical geography of the time, 

 little is certain but this, that almost the whole of the area 

 now called Scotland was under the sea, during the time 



1 See ' Geological Map of Scotland,' last edition, by Archibald 

 Geikie, LL.D., F.R.S., 1876. 



