Old Red Sandstone. 1 1 1 



The first patch lies between Fyvie and Penman Bay in 

 Aberdeensbire ; the second forms both shores of Moray 

 Firth and Dornoch Firth, and stretches a long way up 

 the Great Valley of the Caledonian Canal, through 

 which at one time I have no doubt it passed all the 

 way to the Firth of Lorn, between Oban and the island 

 of Mull ; and the third forms the greater part of Caith- 

 ness. On the west coast a large tract of hilly ground 

 between the neighbourhood of Loch Awe, Oban, and 

 Kerera is chiefly formed of Old Red conglomerate. 



For the first compendious account of the Old Red 

 Sandstone of Scotland the world is indebted to Hugh 

 Miller, whose wonderful faculty of graphic description 

 enabled him, unassisted, to describe the rocks and the 

 remarkable forms of fish they contain, which till his 

 time were almost altogether unknown. Something, 

 however, still remains to be done, before the precise re- 

 lations to each other of some of the parts of the 

 Old Red Sandstone of Scotland are clearly established. 

 The researches of Professor Greikie and other officers of 

 the Geological Survey, have shown that, south of the 

 Grampian Mountains, there is an upper set of strata, 

 lying in basins unconformably on the lower Old Red 

 Sandstone. 



Conglomerate often lies at the base of any part 

 of the series that rests directly on the ancient slates 

 and gneissic rocks, and occasionally thick conglo- 

 merates are intercalated among the sandy strata on 

 various horizons, as, for example, on Moray and Cro- 

 marty Firths. These beds are sometimes thin, and 

 sometimes of enormous thickness. Some of these con- 

 glomerates are clearly volcanic breccias and ashy beds ; 

 as, for example, on part of the Ochil Hills, south of the 

 Firth of Tay, and from thence stretching westward at 



