206 The Agecroft Valley. 



It is unnecessary, accordingly, to do more here than to 

 refer to that little book, and to add that for the geolo- 

 gist, no less than for the botanist, the valley of the Irwell 

 has very considerable attractions. The great ridges we 

 found at Greenfield, &c., though so much loftier, are 

 immensely more ancient than any exposed portion of the 

 country here, which ranks probably with the youngest, so 

 to speak, that is anywhere to be met with in the neigh- 

 bourhood. With the remainder of the chain of hills to 

 which they belong, (commonly called the "Pennine,") 

 those great ridges form the eastern margin of an enor- 

 mous and very irregular stone basin, tilted up in such a 

 way that the opposite or western edge is concealed far 

 beneath the surface of the ground, nobody knows exactly 

 where, but bearing away towards the Irish sea ; and it is 

 within or upon the floor of this great basin that all the 

 other Manchester rocks and strata have their foundation. 

 In different portions of its huge lap are deposited the 

 coal strata, (themselves often much elevated from the 

 level on which they were originally deposited, and this* 

 at various periods ;) then, in ascending order, in some 

 parts there are deposits called "Permian;"* above 

 these, in turn, comes the Trias ; and over all, (except on 

 the higher hill-ranges,) is the superficial deposit called 

 " Drift," or sand, clay, and gravel, both stratified and 

 unstratified. This comes of the astounding fact that the 



* On account of their being extensively and typically developed 

 in that portion of central and eastern Russia named " Perm." 



