On the Boulder Clay of Caithness. 399 



organisms, &c. ; and when finally stranded, quantities of the 

 mud, sand, stones, and organisms of the Caithness shores 

 were mingled with them. As the icebergs dissolved the 

 burthen was dropped in a pell-mell manner. The ice pro- 

 tected the materials, and prevented the sea from levelling 

 and arranging them, and giving the deposit a stratified 

 appearance it otherwise would have done could it have acted 

 on it. The gradual dissolving of the bergs gave time to the 

 clay to solidify, and thus it was preserved when its carrier 

 and protector was no more. Once firm, especially in deep 

 water, little injury could be done to it. It suffered most in 

 shallow water, and when exposed to the frosts and wet of 

 winter ; and, although not so much affected by summer sun- 

 shine and showers, even then portions of it would doubtless 

 be carried away. The story of the voyaging and gatherings 

 of the icebergs is well told by the contents of its left bur- 

 then ; for Crag, as seen by its shells, &c. ; Gault, Chalk, and 

 Green Sand by the flints, corals, and Foraminifera, with 

 portions of the Chalk, both hard and soft, some so soft that 

 it may be used for writing with ; Lias and Oolite by the 

 belemnites, ammonites, fossil wood, septaria, &c. ; Silurian 

 by its metam orphic limestone, quartz, and other rocks ; 

 Cambrian by its gneiss, &c, granite, porphyry, &c. ; and 

 then the abundance of the Old Eed Sandstone torn up and 

 mingled with all the others by the ponderous icebergs, as 

 they grated and thumped before finally resting, form a 

 curious but suggestive collection. The organisms are en- 

 tombed in a stubborn and hard material ; it has, however, 

 been made to give up its ancient dead, and to show that at 

 the time of its formation life was as abundant as now, 

 and that, with few exceptions, the same species found in it 

 are now living in the present seas, many around our own 

 shores, some few in the Arctic Seas only, and probably one 

 or two may be extinct — I say may be, from having been 

 taught great caution by so many of those said to be extinct, 

 having been from time to time dragged from ocean's depths 

 by our active dredgers. I feel now it is best to say probably 

 extinct. Several species of Foraminifera (not mentioned 



