AND QUARTZ DEPOSITS OF ASSYNT. 357 
color, non-calecareous,— for they do not effervesce on the appli- 
cation of the most powerful acids,—and containing usually a 
brown oxydized substance in their interior. In the better, at 
least more distinct, specimens, they somewhat resemble frag- 
ments of serpula, or those segments of dentalia which one oc- 
casionally finds in the boulder-clay of Caithness; but they are 
in all probability not the remains of either annelid or mollusc, 
but mere effects of the oxydization, under peculiar circumstan- 
ces, that has discolored the matrix in which they lie. Iron 
pins or nails we find not unfrequently represented on sea- 
beaches where wrecks have taken place, or near some dock- 
yard or harbor, by mere oxydized tubes, hollow within; and it 
is not improbable that to minute, pin-like crystals of some min- 
eral or metal now represented by only the oxydized substance 
enclosed within the hollow, do these little tubes owe their ori- 
gin. I at least wholly failed to satisfy myself that they are 
organic in their character; nor do I suppose that they would 
be by any means the oldest of Scottish fossils, even if they 
were. 
This upper quartz rock forms the highest and most modern 
deposit of the marble districts. Taking the summit of Ben- 
more as its apex, a shaft sunk on the top of that noble hill, to 
the depth of perhaps eight or ten thousand feet, would pass in 
succession through the first or upper quartz, through the lime- 
stone with its associated marbles and flagstones, through the 
second or lower quartz, through the red sandstone, with its 
conglomerate beds; and finally, it would reach the uncon- 
formable gneiss, on which the whole system rests; for as one 
system must these four great deposits be regarded. Where, 
among the other systems of Scotland, I ask, are we to seek for 
its analogue and representative ? 
Let me first remark, that the Lower Old Red Sandstone of 
the east coast of Scotland, as developed in Inverness, Ross, 
