W. SH0KE ON THE GLACIAL DEPOSITS OF WEST CHESHIRE. 389 



manner in which the shells were distributed in the Boulder-clays, 

 and how the Gastropoda filled with silt containing Microzoa are 

 found in a matrix of red clay. That the Gastropoda so filled are 

 spread over a wide area I am able to affirm, having obtained them 

 from various localities in Boulder-clays in Lancashire, Cheshire, 

 Flintshire, Denbighshire, Shropshire, Staffordshire, and the Isle of 

 Man. With regard to height above the sea, the Gastropoda con- 

 taining silt with Microzoa are as common to the Boulder-clay of 

 Macclesfield, which overlies the Middle Sands and Gravels, and that 

 at Arnfield, Cheshire, above 600 feet up on the flanks of the Pennine 

 Chain, as they are at the sea-level in the Lower Boulder-clay of 

 Dawpool*. Among the Foraminifera Rotcdia Beccarii and Bulimina 

 pupoides are the most persistent species, being found in the Gastropoda 

 from the Boulder-clay of Macclesfield and Arnfield to that of all the 

 counties above mentioned. They are two of the most common 

 littoral species of our shores. The Scandinavian facies of the fauna 

 from the Upper and Lower Boulder-clays establishes that the climate 

 would be cold enough for the formation in winter of coast-ice on the 

 then shores, while the employment of ground-ice for the distribution 

 of the shells in the Boulder-clays does away with the difficulty of 

 the deposition of the finer particles of the clay, as the water might 

 be sufficiently still in the depths of the sea for its accumulation, 

 while the ice-rafts from the coasts were floating upon the surface, 

 discharging as they melted their freights of sand, broken shell, 

 gravel, and striated erratics gathered from the more distant beaches. 

 This would account for the fauna being littoral and sublittoral, and 

 of species whose habitats are among seaweeds, rocks, and sands 

 being mingled confusedly together in a common matrix of clay. 



The mingling of northern and southern forms together in the 



drifts demands some explanation. From an analysis of the fauna of 



these deposits in Lancashire and Cheshire, it appears that northern 



shells are more common in the clays, and rarer in the Middle Sands 



and Gravels, while, on the other hand, southern shells are rare in 



the Clays and more common in the Middle Sands and Gravels. If 



we turn to the physical aspect of the drift, it will help us to clear 



up the difficulty. Thus, the Lower Boulder-clay at its junction 



with the Middle Sands and Gravels is most generally eroded, and 



bears the marks of having once been far more extensive than at 



present. The Lower Boulder-clay contains a Scandinavian fauna ; is 



it not therefore more than probable that the Scandinavian shells of 



the Middle Sands and Gravels have been derived from the Lower 



Boulder- clay? and thus we have, as at Leylands, Trophon Fabricii 



with Mactra glauca, and again, at Macclesfield, Astarte borealis with 



Area lactea. Again, if we examine the gravels, we find them largely 



composed of the granites, porphyries, limestones, and grits which 



* Mr. R. D. Darbishire, B.A., F.G.S., gave me some silt &c. containing 



Foraminifera which he had gathered from the beach at Gorteen, Connemara, 



Ireland. My mother, Mrs. Shone, on examining this debris, observed that the 



fry of the Gastropoda, which abounded in it, were all filled with this Forami- 



niferal silt, and only awaited the formation of ground-ice on the shore to repeat 



the phenomenon of the Gastropoda of the Boulder-clays. 



