Rev. P. B. Brodie — Sand-pit near Rugby. 321 



the list (except one species) picked off the Crosby shore either by 

 myself or my sons. Species and genera the most diverse in habitat 

 are thrown up on the shore, and the same may just as readily have 

 happened in the glacial sea in glacial times. Again, it is urged that 

 there are shells whose habitats now are southern, mixed up with 

 boreal types, and that they could not have lived together in the same 

 sea. The only shell of southern type that has anything approaching 

 a wide distribution in the Drift is Venus chione, and that is now 

 found living in Carnarvon Bay. The southern types of shell appear 

 to be more frequent (though only two species are recorded from 

 Gloppa) in the High-level sands and gravels than in the Low-level 

 Boulder-clay and sands ; and this is consistent with the amelioration 

 of the climate which set in with the submergence. Some Tertiary 

 shells are now only boreal in their habitats, notably Tellina calcarea,^ 

 a common fossil of the Scotch drift ; yet it hardly would be con- 

 tended that any part of the Tertiary period was colder than the 

 present. The fact is we are ignorant of the causes that govern the 

 distribution of molluscs, and are not in a position to say that it is 

 solely temperature. At Cape Cod, in latitude 42°, arctic and southern 

 forms are now dredged up alive from the same bottom. Finally, 

 the great majority of the mollusca of the Drift are now found living 

 in the Irish Sea. Not only so, but the most common species of the 

 Drift of the north-west of England are the most frequently found 

 now on the sandy shores of Lancashire. If a few boreal forms were 

 introduced among the living molluscous fauna of the Irish Sea, and 

 two or three southern types less freely, we should have a pretty close 

 reproduction of the fauna of the Drift. The shells of the Drift are 

 little distinguishable in condition from those of recent molluscs, 

 which I believe are lineal decendants of those that occupied the 

 Irish Sea in Glacial times. 



The remarkable equality of maximum level of the high-level 

 sands and gravels with shells scattered over an area 190 miles wide 

 from east to west points towards deposition by the sea rather than 

 by land-ice. 



With this I must for the present conclude, for though I have far 

 from exhausted the illustrations and arguments gained in the field 

 during the last twenty years, the reasonable limits of space prevent 

 me from expanding them. Enough, I trust, has been said to show 

 that the Glacial deposits, being fairly interrogated, speak strongly 

 in favour of a glacio-marine origin. 



VI. — A Sand-Pit at Hill Morton, near Eugbt. 

 By the Rev. P. B. Brodie, M.A., F.G.S. 



DURING a recent visit of the Warwickshire Naturalists' and 

 Archaeologists' Field Club to Rugby, a very interesting section 

 was examined at Hill Morton. It consists, for the most part, of 

 brown and light-coloured sands, exposed near the London and 



^ " Occurs in every Tertiary bed up to the Red Crag " (Jeffreys, British Conchology, 

 vol. ii. p. 390). 



DECADE III. TOL. IX. — NO. VII. 21 



