Chap. XI.] 
OLD RED SANDSTONE OF CAITHNESS. 
255 
3 
of the east coast have been formed, mica-schists 
prevail in Easter Eoss ; whilst as we proceed 
northwards into Sutherland, particularly in the 
Scarabin Hills, quartz-rocks predominate. Now 
the quartzites of these mountains present just 
the same bedding, and alternate with schists, as 
in the western parts of the country, where the 
Lower Silurian fossils have been discovered. 
Thus, in descending from the Scarabins to- 
ss .s wards the sea, we meet with a regular suc- 
■B g cession of crystalline or subcrystalline, light- 
_g.§ coloured, thin-bedded quartzites with argil- 
laceous wayboards, and presenting all the 
jj "i aspect of a sedimentary origin, which, rising 
| 8 ® a ^ high angles to the summits, are followed on 
■§ -g I their eastern flanks by other siliceous courses 
& <§» a (some micaceous), of various colours from 
dull purple-brown to grey. At certain spots 
"gp © | these quartzose rocks are broken up and pene- 
"fj'c -51 trated by granite. It is upon the edges of 
g these rocks, as ranging from the Ord of Caith- 
J «5s m ness by the Scarabins to the Morvein Hill, that 
the base of the Old Red series of Caithness 
^Ph % rests, the conglomerates composing the last- 
;|o j? mentioned of these mountains occasionally 
^ | | rising, along this fringe only (as Hugh Miller 
^ £ has we H remarked), to higher altitudes than 
^ a the older crystalline rocks. 
.3 A Let us now consider the overlying series in 
§ S § a * rue ascena ^i n S order, by proceeding from 
'i § the inferior red sandstones and conglomerates, 
8 | through the central masses of dark-grey flag- 
^2 stones and schists, to the higher sandstones 
<s % which stand out in the northern headlands of 
*5 Caithness and the Orkney Islands. The ac- 
| companying diagram indicates this succession 
I in a general and compendious manner, the 
e g many detailed flexures and breaks in the strata 
being omitted. 
Ph In describing the different parts of the 
ssi § lowest member of the Old Red Sandstone, it 
^ e would be superfluous to enumerate all the ex- 
amples of splendid and massive conglomerates 
and sandstones, particularly those of Easter Ross, which, reposing on the 
