A HISTORY OF STAFFORDSHIRE than a few feet across, which has been traced from near Keele to a little north of Chebsey. 1 In its course it cuts across and alters rocks of Upper Coal-measure, Bunter and Keuper ages. The mineral constituents are exceedingly fresh, and in many respects the rock closely resembles the South Staffordshire intrusions. . PLEISTOCENE AND RECENT GLACIAL DEPOSITS The third great epoch of which the county presents a complete and most interesting record is that of the Pleistocene or Quaternary Period. There is abundant evidence to show that at this late geological time two great ice sheets were formed by the piling up of snow and ice over the North Sea and the Irish Sea and converged until their margins touched in Staffordshire somewhere in the region of Burton-on-Trent ; at the same period local glaciers descended from the Derbyshire and Welsh hills, spreading out their debris at their feet and mingling it with that carried inland by the two great ice sheets coming up from the sea. Compared with the events recorded in the latest of the solid geolo- gical formations the Rhaetic dealt with in this article, this refrigera- tion, which extended over the whole of northern Europe, happened but yesterday, its close according to some calculations not being further removed from the present day than 10,000 years. At its commence- ment the configuration of the land was much as it is to-day ; all that it accomplished was a little rounding off of surface inequalities by the rasping power of the ice and the filling up of pre-existing hollows or alteration of previous surface drainage by the accumulation of detritus or by barriers of ice. To understand the significance of the phenomena met with in Staffordshire it is essential to bear in mind that the Welsh, Cumbrian, Scotch and Pennine hills were as high at the commencement of the period as they are to-day, and that the chief valleys and plains of central England were in the main blocked out. This being recognized, the course which the ice sheets took will be easily comprehended. The one from the Irish Sea invaded the Cheshire and Shropshire plains, to be there joined by the more local ice flows from the Welsh hills ; the one from the North Sea spread over the eastern counties and pushed its way up the Trent valley, to be joined near Derby by the glaciers sent off from the Derbyshire hills. Such are the broad general outlines of the period. The existence of these moving masses of ice is plainly demonstrated by the character of the foreign material or train of boulders left scattered over the country, and by the ice grooves on the solid rocks radiating outwards from the elevated regions or pointing in the direction of the paths taken by the Irish Sea and North Sea ice. The three largest glaciers have been named : (i) The Arenig Glacier, 1 J. Kirkby, ' On the Trap Dykes in the Hanchurch Hilh,' Tram. North Staff. Field Club, vol. xxviii. (1894). 26
