454 MR. E. HULL ON THE DRIFT-DEPOSITS 



however, the superposition of the two formations takes 

 place along a very level and clearly defined line_, as may be 

 observed in a large pit at Openshaw and Clayton Hall. 



The Lower Boulder-clay j or Till. — Over the district south 

 of the Mersey, the Lower Boulder-clay rarely makes its ap- 

 pearance, the country being overspread by the Upper Till, 

 resting on the sand. The Lower Till, however, may often 

 be traced at the bottom of some of the deeper valleys, such 

 as those of the rivers Dean and BoUin and that of the 

 Tame above Stockport. North of the Mersey, at Stock- 

 port, it occupies the tract from Heaton Norris to the 

 Irwell, west of Manchester ; and on the opposite side of the 

 river, from Salford to Leigh. It also crops out at the base 

 of the high banks of sand along the river Roch, from Bad- 

 cliff Bridge upwards for several miles. In the hill- country 

 it seldom or never makes its appearance, as all the Boulder- 

 clay there to be found belongs probably to the upper member 

 of the series. 



The Middle Sand. — This division occurs in great strength 

 at Macclesfield, Prestwich, and Poynton. It forms the 

 banks along the valleys of the Bollin and Dean and Bram- 

 hall Brook. It has a thickness of 50 feet at Stockport and 

 Heaton Mersey, and from the banks of the Tame all the 

 way to Staleyb ridge. Traced from Heaton Norris, it forms 

 a band of slightly rising ground by Beddish, Sandfold, 

 Openshaw, Clayton Hall, and Harpurhey to Blackley and 

 Crumpsall, where it swells out considerably. It covers 

 the country for the most part around Middleton, Boyton, 

 Hey wood, and Bochdale. It forms the high banks along 

 the Irwell and its tributaries, from Pendleton to Bury, 

 Bolton, and up into the hills beyond Sharpies, where the 

 gravel becomes of a very local character, the pebbles being 

 principally formed of Millstone-grit; and it forms a 

 bank of rising ground on its southern outcrop, extending 

 from Swinton westward by Worsley towards Ince in Wigan. 



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