and some other Stratified Deposits in the North of Scotland. 295 



tified, in some localities fine-grained, compact, and of a deep red colour : in 

 others a coarse aggregate of pale-coloured felspar and gray quartz ; whilst, at 

 the points of junction with the secondary strata, it is usually in a decomposed 

 state. In external character as well as in that internal structure which resists a 

 fresh fracture, it strongly resembles the syenite of the Malvern Hills, (described 

 by Mr. Leonard Horner,) to which it presents a further analogy by splitting 

 under the hammer into cuboidal fragments, the interstices of which are some- 

 times coated with oxyd of iron. 



The surface of the greater portion of the valleys is covered with vast quan~ 

 titles of diluvial gravel, principally derived from the adjacent mountain ranges, 

 and diversified with numerous conical and tabular eminences. The strata 

 beneath this diluvium are only occasionally visible ; sometimes in low clifis 

 upon the coast, at other times where the plains are intersected by a stream ; 

 and an acquaintance with many of the beds, is only to be acquired by an 

 examination of the reefs exposed at low water. (See PI. XXXI. fig. 1.) 



The relations between the superior strata and the red conglomerate cannot 

 be observed in the Brora district ; because the lowest beds of the former dip- 

 ping under the sea, are considerably above the base of the series, which will 

 elsewhere be described, in contact with the red conglomerate on another part 

 of the coast. 



The junction, however, between the granitic rock and the superior strata is 

 seen in several places along the interior boundary of the valleys, where the 

 sandstone and shale rest highly inclined or dislocated upon the edge of the 

 mountain range. A striking example is afforded near Clyne church ; where 

 a stream forcing its way down the mountain side has cut several deep chasms, 

 exposing alternations of stratified primitive rocks, nearly vertical and much 

 contorted, consisting of quartz-rock and chloritic and micaceous schist, which 

 last is accompanied by small portions of specular iron and galena. The granitic 

 rock is here and there seen in the bed of the rivulet ; whilst, at the base of this 

 defile, the sandstone and shale of the coal-field rising gradually from Inver- 

 brora, are suddenly elevated in the proximity of the same unstratified rock, 

 which affects the primitive strata in the higher part of the ravine. (See Sec- 

 tion on the line C, D. PI. XXXI. fig. 1, and also fig. 2.) 



I now proceed to detail more particularly the structure of the first of the 

 three valleys before mentioned. 



The district of Brora is about eight miles in length from Golspie to Coly- 

 burn, and about two miles and a half in its greatest breadth, where it is inter- 

 sected by the river Brora ; which flowing in a north-easterly direction from 

 the loch of the same name, cuts through the diluvium of the plain, and pre- 



VOL. II. — SECOND SERIES. 2 Q 



