BOULDER-CLAY AT BRIDLINGION QUAY. oL7 
transported masses they may, lke the rest of the boulders, be of 
any, or all ages. I think, however, there is sufficient evidence to 
show that this is not so, and that all the masses containing marine 
remains (at any rate all that have yet been examined) must be, 
at least roughly, contemporaneous. For, if the beds were of dif- 
ferent ages, or derived from widely separated localities, we might 
expect to find clear and ready proof of this in the fauna; whereas, 
although the species present vary considerably in the different 
masses, the general facies is in every case distinctly the same and 
always arctic. Nor, with the exception of the doubtful Rissow, 
respecting which see notes appended to the list in the Appendix A, 
are any species found save such as might form part of the same life- 
group, though there is some discrepancy in the depths at which some 
of the shells now live. 
There is also the evidence of the matrix of the shells. I regard the 
fine tough blue clay as having been a true glacial mud, deposited ona 
sea-bottom, and the green sand, with its contained pebbles, as having 
originated either in the dispersion and disintegration of morainic 
material or in the destruction of preexisting glacial beds. The ex- 
istence at the time of a sea-bottom strewn with travelled boulders 
is shown by the occurrence in the Basement-clay of numerous blocks 
of various kinds of rock bored by Saaicava, Pholas, or Cliona, the 
borings in the former of these cases sometimes still containing the 
shells and Foraminiferous sand. I also think, from the well- 
rounded and water-worn appearance of most of the smaller boulders 
and pebbles in the Basement-clay, that most of these have suffered 
aqueous erosion at some period of their history after their detach- 
ment from their parent rock and before their incorporation in the 
clay, and that they are the relics of an old shore-line. 
On these grounds I conclude that, though the beds are not in 
place, they have for the greater part had a common origin, and are 
all of one age, which the fauna shows to be glacial. 
It remains to be considered whether this point of origin has 
been near the place where they are now formed, or at some un- 
known distance,—that is, whether the masses are the remnants of 
beds which once existed on this spot, ploughed up and destroyed by 
the passage of ice over them; or whether they may have been far 
transported and here abandoned by the ice in its progress. 
The evidence, though strongly leaning towards the latter of these 
views, I regard as still inconclusive. [or as we nowhere see far down 
into the Basement-clay, and have no knowledge of what takes 
place below the shelly masses (that it is the “‘ Basement” bed at all 
being a surmise), by no means are we able to satisfy the suspicion 
that actual beds in place may occur lower in the section; the pre- 
sence of the supposed freshwater patch, which at first seems to negative 
this idea, could be explained by supposing the existence of a series 
of early glacial marine and freshwater beds like those in Norfolk. 
On the other hand, in strong support of the view that the masses 
may be far-travelled, is the fact that masses of Secondary beds, 
which must have been carried for long distances, and also of chalky 
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