1866.] JAMIESON CAITHNESS. 267 



Fig. 5. — Oil the Thurso Water, near Thurso. 



Sfcream. Farmhouse. W. 



The high, banks on both sides of the stream consist of unstrafcified pebbly clay 

 or gritty mud with a few traces of broken shells. 



from rocks in some part of the county, with the exception of one of 

 granite near Castletown, which he thought was different from any 

 of the Caithness granites, and had probably come from Sutherland, 

 where a similar quality of rock is known to occur. 



4. State of the Shells. — The shells, as a rule, occur in broken frag- 

 ments. The most common kinds are the Oyprina Islandica, Turri- 

 tella ungulina, Astarte horealis, A. elliptica, Tellina calcaria, and T. 

 Balthica. Although broken pieces are the rule, yet exceptions 

 sometimes occur. Thus, during the search that I myself made, I 

 found one entire valve of Astarte horealis, another of A. elliptica, 

 and two small ones of A. compressa, likewise a specimen of Natica 

 nitida and another of JSf. Islandica, both almost perfect. And in 

 the collections of Mr. Joseph Anderson and Mr. Eobert Dick I saw 

 several entire single valves of Astarte and Leda, on which there were 

 occasionally small portions of the epidermis or skin remaining, also 

 entire specimens of Mangelia and Nassa. Mr. Peach has even got 

 a specimen of Anomia with both valves complete, in a fine state of 

 preservation, and this was in the drift containing the usual assem- 

 blage of ice-worn stones and broken shells, the only instance of an 

 entire bivalve that I have heard of. The Tur^itella, which is one of 

 the most common of all the species, although always more or less 

 imperfect, yet frequently occurs in large pieces, some of them not 

 far from being entire. I nowhere observed any instance of the shells 

 being found in an undisturbed condition, nor could I hear of any 

 such having been found ; there seems to be no such thing as a bed 

 of laminated silt with shells in situ. Even the Foraminifera, when 

 seen through the microscope have a rubbed, worn appearance. No 

 clay suitable for the manufacture of bricks and tiles or drain -pipes 

 has been got in Caithnes, it is all too sandy and full of stones. The 

 laminated brick-clays are, in short, entirely absent. 



Many of the shell-fragments show marks of glacial action. It is 

 generally on the stouter pieces of Cyprina and Astarte that these are 

 to be seen, but I found some fragments of Tellina calcaria distinctly 

 marked. Now this is rather a delicate fragile shell, and the fact of 

 its being so marked and yet not crushed to powder, shows how gentle, 

 in some cases, the action must have been that imprinted these 

 markings. Where the shell-fragments are of an elongated form, the 

 scratches run lengthways along them, just as they do on the pebbles. 

 I have one piece of shell, which T picked up myself, not quite an 

 inch long, most beautifully marked with a multitude of fine parallel 

 scratches as if done by the point of a needle, and quite polished even 



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