254 SILUKIA. [Chap. XI. ! 
disposed to consider the Old Red Sandstone a kind of local formation I* 
only, have been unwilling to regard it as the full equivalent in time 
of the Devonian rocks of other countries. 
The massive conglomerates and intercalated red sandstones of the north- 
east coast, which occupy a great thickness of strata in Easter Ross, Cro- 
marty, the Black Isle, and adjacent parts of Inverness-shire, and which, 
flanking the Oolitic tracts of Dunrobin and Brora, range northwards from j 
Sutherland into Caithness, are very distinct in mineral character and rela- 
tions from the ancient Cambrian conglomerates and grits of the west coast. 
Whilst the latter underlie all those quartzites and limestones which are j 
now known to be of Lower Silurian age, the great pebble- and boulder-beds i 
of the east coast and its inland recesses never assume the subcrystalline 
character of some of the western masses. On the contrary, they overlap 
all such rocks ; and, often containing gigantic boulders, invariably derived j 
from some adjacent crystalline rock, they graduate into, and alternate with, 
masses of grit and sandstones as sectile and as well fitted for building- 
purposes as many freestones in the British Isles. Indeed, at places, the 
red sandstone associated with the conglomerate assumes so variegated a 
character, with green spots and stripes, or earthy concretions, that, in 
early days, German geologists, unacquainted with the exact relations of 
the deposit, and judging from mineral characters only, would have referred 
such rocks to the ' Bunter Sandstein.' 
The reader who desires to become better acquainted with the different 
varieties of such conglomerates and sandstones may peruse the descriptions 
given of them by Jameson, Boue, and the earlier writers, as well as by 
M'Culloch, Sedgwick, and myself. 
Among the various authors who have described them, the lamented 
Hugh Miller stands preeminent. Born upon the Old Red Sandstone of 
Cromarty*, he has shed a bright lustre over this deposit of his native 
tract, and has expounded with a surprising sagacity the wonderful organ- 
ization of many of its fossil Fishes, and thrown the clear light of zoology j 
upon these old pages of geological history. 
The term Old Red Sandstone having thus been rendered classical, the 
name may well be retained as a synonym for the great group, of inter- 
mediate age between the Silurian rocks beneath and the Carboniferous 
formation above it, which, in those countries where it assumes more cal- 
careous, schistose, and slaty characters, is termed ' Devonian/ 
Among the older crystalline rocks which, rolling over from the west, 
constitute the masses out of which the red sandstone and conglomerate 
* See Hugh Miller's remarkable work, 'The the adjoining property of Bed Castle, varieties of 
Old Red Sandstone,' in the dedication of which to the building-stone have long been quarried. Ross- 
myself he alludes to our both being born upon shire now affords, indeed, so many quarries of 
the Old Red Sandstone. In physical geography, building- stone, both bight and dark red, and 
Cromarty, the birthplace of Miller, forms a part sometimes ribboned or spotted, that in proceeding 
of the peninsula of Ross-shire known as the Mull- from Inverness to Sutherlandshire by Dingwall 
Buy, or the Black Isle, in which my paternal and Tain the traveller has ample evidence of the 
estate of Taradale is Bituated, and where, as in varied nature of the rook. 
