CHAPTER XXXVIII 

 THE NORTHERN DRIFT. 



1 . On a Northern Drift containing granite bowlders and sea shells of existing 

 species, which covers large parts of Lancashire, Cheshire, Shropshire, Staf- 

 fordshire and Worcestershire ; prefaced by a sketch of the probable condition 

 of the surface before and during its deposit, comprising a short account of the 

 local detritus which the northern drift covers and with which it is partially in- 

 termixed. 



Quitting the Silurian region, which is covered with local detritus only, and pass- 

 ing its northern or eastern limits, we enter districts where a large portion of the accu- 

 mulations are associated with others which have been transported from Cumberland, 

 and probably even from Scotland. 



The former hydrographical condition of this tract cannot, however, be considered 

 without assuming the following positions, which are established in the sequel. 1st. That 

 the granitic and other detritus derived from the north, constitutes, wherever it is found, 

 the uppermost part of the drifted matter, and contains sea shells of existing species. 



2nd. That this granitic and shelly detritus never enters into the region occupied by 

 the Silurian drift, but sweeping round its northern face, extends in an elongated deltoid 

 form along its eastern flank, either covering or mixing with the local drifts with which 

 it comes into contact. 



By the term northern drift is, therefore, simply meant an accumulation of materials, 

 the chief mass of which had a northern origin ; for here, as in the region of Siluria, there 

 are also evidences of local drifts. Now, though we may be unable, on all occasions, 

 rigorously to define the demarcation between the local drifts and the northern drift, 

 yet from structure and composition there can be no doubt that all these accumulations 

 were formed by long- continued aqueous action; and that the northern granitic detritus 

 with marine shells of existing species indicate the last of such operations. Evidence 

 will hereafter be adduced to show, that while this northern drift was accumulating, 

 that is, during the latest period at which the region was submarine, not only was Siluria 

 above the waters on the west, but also a large portion of England on the east. The 



