680 T. M. READE ON A SECTION OF BOULDER-CLAY 
Prof. Hull’s lead, divide the Drift into three parts (viz. Lower 
Boulder-clay, Middle Drift or Interglacial Gravels, and Upper 
Boulder-clay), I was much struck by the section. If it had occurred 
in Lancashire there is no doubt it would at once have been set 
down as a very good example of the “ Interglacial Gravels” and 
‘‘ Upper Boulder-clay.” 
I had not many minutes to examine the section, but I picked up 
during the time I was there a few of the shells and shell fragments. 
These I submitted to Mr. R. D. Darbishire, F.G.S., of Manchester, 
who has determined the following species :—Astarte elliptica, A. 
compressa, Leda pernula, Mactra elliptica, Natica, and Mytilus. 
On comparing these with my list of shells from the Boulder-clay 
about Liverpool*, I find that during several years’ close search 
Astarte compressa only occurred in great rarity in the numerous 
localities I examined; and according to Mr. Darbishire’s list it is 
“‘very rare” at Blackpool. Astarte elliptica was frequent in some 
localities and rare in others. Leda pernula, supposed to be a typical 
arctic shell, was very rare in the localities where it was found. 
There is thus, according to shell-evidence, nothing to give an 
‘“« Interglacial” character to these gravels as compared with either 
the so-called Upper or Lower Boulder-clays of the north-west of 
England. My opinion has long been against this tripartite classi- 
fication, and I have pointed out more than once that it rests upon 
no intelligible basis. The examination of the Irish Drift still further 
confirms me in the opinion that the marine Boulder-clays of the 
north-west of England and Ireland are but phases of one long se- 
quence of events uninterrupted by changes of climate. 
Prof. Hull has applied the same classification of “‘ Lower Boulder- 
clay,” ‘‘ Middle Sands and Gravels,” and “ Upper Boulder-clay ” 
to the Drift of Irelandt. It is quite evident, however, if the 
Boulder-clays of Galway Bay, as represented by the sections at 
Blake Hill, and the Fermoy valley in county Clare on the opposite 
coast, as well as the innumerable islands of Drift in Clew Bay, are 
members of the ‘“‘ Lower Boulder-clay,” it is quite a different thing 
from the Lower Boulder-clay of Lancashire. The latter is marine, 
the former contains no evidences whatever of marine conditions. 
On the north shores of Belfast Lough, beneath the celebrated 
raised beach, are to be seen sections of a Boulder-clay that corre- 
sponds in appearance with the marine Boulder-clays of the north-west 
of England. Large glaciated blocks of travelled stone, some of 
which I could have matched with erratics taken out of the Bootle 
Dock excavations, are to be seen on the beach washed out of the 
low cliffs of purple Boulder-clay, which is evidently, as in Cheshire 
and Lancashire, largely reconstructed from the Triassic Marls. I 
did not notice any shell-fragments in the Belfast Boulder-clay ; but 
my time was limited, and in Lancashire it often requires close ex- 
‘amination to detect them. 
* Quart. Journ. Geol. Soe. vol. xxx. p. 27. 
t See Geol. Mag. dec. 2, vol. iv. pp. 38, 39. 
| Physical Geology and Geography of Ireland, pp. 79-95. 
