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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 26, 



erratic detritus, about twenty feet thick, interposed between the rock 

 and the clay, and similar to the sand above the clay. 



A large portion of the materials, both of the sand and clay, have 

 been derived from the strata of the New Red, mixed with detritus 

 from the Carboniferous hills on the east, as well as with a great 

 abundance and variety of granitic and slaty fragments, transported 

 from the north. 



The larger northern boulders appear to belong chiefly to the Upper 

 Sand, but are occasionally found in the Till. This consists of a red 

 clay, containing many small fragments having a northern origin, and 

 much detritus derived from the neighbouring chain. 



I have seen shells in the erratic deposits at four points ; namely, 

 in a sand-pit of the Upper Erratics, about three miles north of Mac- 

 clesfield, on the Stockport road, — about two miles south of Maccles- 

 field in gravelly clay, evidently derived from an adjoining cutting, — 

 in the same kind of deposit in a cutting at the Northrode Station four 

 miles, and in a pit by the Dane Viaduct six miles, south of Maccles- 

 field. The shells were in the state of finely comminuted fragments 

 in the sand-pit on the Stockport road. At the other spots, although 

 still small, they were of sufficient size to permit the recognition of the 

 genera Turrit ella and Cardium. 



In this district, as in others which I have examined on the eastern 

 coast, in Wales, and in Ireland, the variations of soil are dependent 

 on the amount of denudation to which the Erratic Tertiaries have been 

 subjected, and on the depth and composition of the unconformable 

 deposit, or "warp," thrown down on this denuded surface. By re- 

 ference to the Ordnance map, it will be seen, that a tract of very 

 broken ground extends from Alderley Park, by Capesthorn, to Sid- 

 lington and Gaws worth. The numerous hillocks with which the 

 tract is studded are caused by the partial denudation of a ridge of the 

 Upper Sands. Though light soils predominate, this district affords 

 every variety from sand to clay, the sandy soils being chiefly on the 

 summits and steep sides of the hillocks, and the clay in the valleys 

 between them, in which latter the denuding process has reached the 

 Till. The loams, varying in depth and in the proportion of the alu- 

 minous matter contained in them, are spread over the long slopes. 

 The general distribution of sand and clay, dependent chiefly on the 

 Erratic Deposits, is shown, as well as it can be on so small a scale, 

 on the map accompanying Dr. Holland's Report on Cheshire to the 

 Board of Agriculture. 



On the eastern skirts of Macclesfield, the superposition of these 

 sands to the Till is well exhibited. For about four miles south of 

 that town, the Macclesfield canal runs along the upper surface of the 

 Till in a valley, where the Upper Erratics have been much denuded, 

 between the ridge of sand and the carboniferous hills. At a place 

 called Bullgate the canal makes a descent, by twelve locks, which 

 cannot be less than 1 20 feet ; and then runs for a mile, first along a 

 terrace of reconstructed gravel, and then on reddish sand, resting in 

 some places on red marl, in others on dark coal-shales. 



The rocks beneath these deposits appear to have a very irregular 



