1866.] JAMIE80N CAITHNESS. 265 



its course ; but for a mile or two above Halkirk pieces of shells are 

 more common, and occasionally an entire valve may be met with. 

 So thickly packed is this drift with small stony rubbish that in many 

 places almost every handful of mud contains several fragments. 



Along the banks of the Haster Burn, near Wick, large stones are 

 more common in the drift, and there are even some considerable 

 boulders ; but notwithstanding the coarse stony nature of the deposit, 

 this is one of the best localities for fossils, fragments of shells being of 

 frequent occurrence dispersed in the unstratified rough stony mud ; 

 and in the course of a single visit to this stream, in company with 

 Mr. Joseph Anderson of Wick, I got an entire valve ofAstarte horealisy 

 and one or two specimens of Turritella and Nat lea nearly perfect. 



At the south branch of the Dunbeath stream, the sections are 

 similar to ihose on the Thurso river, and pieces of shells about equally 

 common. In the bed of the Forss the drift is veiy full of stones, and 

 shells are exceedingly rare ; otherwise it resembles that of the loca- 

 lities just mentioned. 



Pig. 3. — Section at Wick Bay. 



i-^-;r-;i-7r:x? 



1 . Reddisli-brown clay with boulders. 



2. Dark pebbly silt with bi'oken shells. 



3. Old Red Sandstone. 



At Wick, however, it is somewhat different ; in the banks beside 

 the harbour (at Pulteney town) the drift is 50 or 60 feet deep. 

 The lowermost two- thirds of it are a sandy mud, or silt, of a very 

 dark grey colour, solid and firm as if much compressed ; and although 

 there are a good many small pebbles dispersed through it, yet they 

 do not form a large proportion of the mass, and there is an absence 

 of big stones. Fragments of shells are in many places not uncom- 

 mon, and are scattered through it in an irregular manner, not 

 occurring in horizontal lines or seams. There is, in short, no dis- 

 tinct stratification, although in some places there is an approach to 

 it, owing to patches of a more sandy nature occurring ; it is an 

 imstratified pebbly silt, the greater part of the mass consisting of 

 fine sand. The upper part of the bank, on the other hand, is of a 

 browner, more ferruginous colour, much coarser in quality, with 

 more muddy sediment and few or no shells ; it is also full of stones 

 and large ice-worn boulders of sandstone, quartzose, mica-schist, 

 and granite, on which the glacial scoring is well marked. One of 

 these granite blocks is 12 feet in length. I cannot say that 

 there is any clear sharp line of separation between this coarse upper 

 stuff and the dark siltier matter beneath ; for although in some places 

 the distinction is pretty well marked, in others they seem to gra- 

 duate into each other. Where the rock rises in the cliff, the dark 

 silty portion thins out, and the coarse brown mud full of boulders 

 rests immediately upon the ice-worn surface of the Caithness flags. 



VOL. XXII. PART I. U 



