124 T. M. READE OJST THE DEIFT-BEDS OF THE 



a typical section at Bootle Lane, as well as given a list of the shells 

 and shell-fragments found in them by me, amounting to 44 species ; 

 this list has been increased by Mr. Shone by his finds at Newton, 

 Cheshire, to 56 species ; 16 species of Eoraminifera were also deter- 

 mined by Mr. D. Robertson of Glasgow, out of one sample of clay I 

 sent him. Ostracoda also occur, and other minute reliquiae of the sea*. 

 My object in these preliminary investigations was to ascertain if there 

 were any organic remains by which the drift-beds might be separated 

 into geological horizons — because,if, as some maintain, two glacial and 

 one interglacial period are represented in these beds, there ought to 

 exist, a priori, some decided distinction in the molluscous fauna. I 

 utterly failed to detect any ; nor is it maintained that any subsequent 

 observations have succeeded, though the observers have been many 

 and zealous, and only anxious to make the discovery. 



The fades of the fauna is of a more northern character than that 

 of the existing Mollusca of the British seas, the typical shell being 

 Astarte borealis, which I found in almost all the localities, though 

 Turritdla terebra is the most abundant. 



I do not place much reliance upon the pakeontological evidence in 

 this case, either as determining age or climate. The Clyde laminated 

 brick-clays contain an assemblage perhaps more distinctly northern 

 than that of my list ; yet these laminated clays can scarcely be consi- 

 dered other than Postglacial, and are certainly of a date long posterior 

 to the beds I am now describing. I have therefore ceased to attach 

 much value to this kind of evidence unless backed up by facts of 

 another and more complete kind f . 



The most distinct and reliable signs which justify us in calling 

 these beds Glacial are the numerous striated and planed erratic 

 blocks, boulders, and pebbles they contain. I have made a large 

 collection of these included rocks from various localities in the 

 neighbourhood of Liverpool %. 



These various rocks occur promiscuously through all the beds of 

 the Low-level Boulder-clay, their proportions changing in different 

 localities ; so that I have found it impossible to separate the beds by 

 the included stones. 



In the Drift of the upper part of the Eibble valley an order of 

 arrangement vertically may be made out, as I have already described, 

 but never in the true sheet of Low-level Boulder- clays and sands. 

 The larger blocks (say, weighing upwards of a ton) are usually fluted 

 in the direction of their longer axes, and are convex in cross section. 



* And in 1882 in samples of clay sands and gravels from the North Docks 

 and Atlantic Docks, described by Mr. Robertson in the Appendix. 



t Mr. Searles Wood has brought forward considerable evidence to prove 

 that the east-coast beds are older than the west-coast deposits ; but my faith in 

 the inferences drawn from the contained shells is much shaken. The east-coast 

 glacial deposits are much more disturbed than most of those described in this 

 paper. On the other hand the erratics of the west coast are more distinctly 

 planed and striated. 



\ Much valuable information on the subject is to be found in Mr. Mackin- 

 tosh's paper " On the Limits of Dispersion of the Erratic Blocks of the West of 

 England/' Quart. Journ. Geol. Soc, 1879, pp. 425-455. 



