6 



POST-TERTIARY ENTOMOSTRACA. 



1. WiGK Harbour. 



We examined the fossiliferous Boulder Clay at Wick Harbour and Burn of Haster, 

 for Ostracoda. It is a hard compact mass with striated and polished boulders, similar in 

 composition to that Boulder Clay in the Avest of Scotland, in which we have failed as yet 

 to detect fossils. We are unable to make any physical distinction between the two 

 Boulder Clays now mentioned. 



The Caithness Boulder Clay varies in depth and is generally overlain by shingly gravel, 

 succeeded by surface soil. The fossils are thinly interspersed from top to bottom through 

 the section, and are very much worn and fragmentary. They appear very equally distri- 

 buted, as if the whole mass had been mixed up and kneaded together, and can be obtained, 

 although sparingly, on the face of weather-beaten sections. On some strong valves of 

 Cyprina Islandica glacial strige may be observed. 



Mr. Jamieson gives the following section at Wick Harbour : 



1 . Reddish-brown clay, with boulders ; 



2. Dark pebbly silt, with broken shells ; 



3. Old Red Sandstone ; 



and adds the following description : " In the banks beside the harbour (at Pulteney 

 Town) the drift is fifty or sixty 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 uncommon, and are scattered through it in an irregular 

 manner, not occurring in horizontal lines or seams. There is, in short, no distinct 

 stratification, although in some places there is an approach to it, owing to patches of a 

 more sandy nature occurring ; it is an unstratified 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 twelve feet in length. I cannot say that there is any clear 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 

 graduate into each other. When 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."^ 



We washed 12 lbs. of the dry shell-bearing clay, and found that it lost 4 lbs. 

 through a sieve of ninety-six threads to the inch, leaving 8 lbs. residue, of which 2 lbs. 



1 'Quarterly Jonrnal of Geol. Soc.,' 1866, vol. xxii, p. 265. 



