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 metamorphic 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 
