256 SILUKIA. [Chap. XI. j 
crystalline rocks of Ben Wyvis and other mountains, constitute the base of 
this series. Exhibitions of such rocks may be seen in the Hills of Moy near I 
Brahan Castle, and again in ascending the Orron, Connan, and Alness j 
Rivers ; and they range thence eastwards all along the southern flanks of 
Ben Wyvis and its associated mountains, and, traversing the Kyles of Dor- 
noch, extend through the eastern parts of Sutherland into Caithness. 
On this coast, beginning at the north side of the mouth of the Beauley j 
Loch, there is a most splendid exhibition of the coarsest of these conglo- 
merates, chiefly made up of granite and gneiss, on the shore between Kes- I 
sock Perry and the House of Drynie, and along the mouth of Munlochy, j 
particularly at the point called Craigie How. Thenceforward to the north 
they appear at intervals, and are exhibited at Ben-a-Bhraggie, close to 
Dunrobin, and in the ridge extending to Golspie and the Ord of Caithness, 
and there forming the base on which the Oolitic deposits of Brora are 
deposited, as described by me in 1826 *. 
In Boss-shire the banks of the Biver Alness, particularly near Ardross 
Castle, the seat of Mr. A. Matheson, M.P., exhibit intercalated masses of 
the red oxide of iron, amid conglomerates and sandstones. Other splendid 
examples of such conglomerates are seen in the deep narrow gorge in 
which the Alt Grant flows. It is in these beds, particularly near Mount 
Gerald, that the bituminous mineral called Albertite has been found, appa- 
rently in lines of joint, and also at several places along the south-eastern 
flank: of Ben Nevis, and in the associated schists of StrathpefFer. This 
Albertite has possibly been derived from the conversion of the Fishes and 
associated marine Plants of the deposit into bitumen, which, exuding from 
the beds, has flowed into the chinks and vertical fissures of the rock, and 
has there been indurated. The tenuity of these linings of the joints : 
renders it highly improbable that this mineral will ever be found in suffi- 
cient quantity to render it of commercial value, like the Albertite of New 
Brunswick. 
Though in many of these localities, particularly in Boss-shire, these 
conglomerates are of vastly greater dimensions than in their extension into 
Caithness, there is no tract in which their relation to the overlying richly 
fossiliferous deposits is so well seen ; and hence the section selected as a 
type is that which proceeds from the maritime promontory called the Ord 
of Caithness, where granite has been powerfully intruded among the older 
rocks. There, and in the recesses extending south-westward from Brae- 
more along the edges of the quartz-rocks of the Scarabin Hills, are ex- 
posed fine masses of conglomerate and sandstone dipping north-eastwards 
at a low angle. The same conglomerates form, in fact, the inland girdle 
of Caithness, rising up on the west from beneath the great flagstones of 
that low undulating country, and separating those strata, so replete with 
fossil Pishes, from the above-mentioned crystalline rocks. 
* Trans. G-eol. Soc, 2nd series, vol. ii. p. 293. • 
