FOUND NEAB BLACKPOOL. 133 



The above tables shew that the surface till of Manchester 

 differs from that of Blackpool in having a much smaller pro- 

 portion of granites, igneous rocks, slates, silurians, and striated 

 stones, and a much greater proportion of coal measure rocks. 

 This, as might have been expected, if we assume a force 

 moving, from the north-west to the south-east, for one-half the 

 distance between Blackpool and Manchester, as may be seen 

 by looking at a geological map, is over the great Lancashire 

 coal-field. The two rival theories put forth to account for the 

 phenomena found in the till, namely, the iceberg and wave of 

 translation, or a combination of them both, might each account 

 for the difference; but the beds of stratified silt, both at 

 Manchester and Blackpool, present appearances which no 

 wave of translation can account for, as they must have been 

 deposited in moderately still water. The striated and polished 

 surfaces of the stones seem to indicate the action of glaciers, 

 or rubbing of a mass of ground ice over a rocky bottom. 



The lower bed of till, composed nearly of one-third its bulk 

 of stones, presents appearances such as are not seen in the 

 upper beds either at Manchester or Blackpool, for the majo- 

 rity of the rocks found in it bear marks of strias, or have 

 polished surfaces. Some of them are stuck into the clay right 

 on their edges, and others at every variety of angle. Although 

 the rocks here are far more numerous than in the till at 

 Manchester, or in any of the beds superior to the silt at 

 Blackpool, still I have met with more large specimens, say 

 those exceeding two tons, at the former place than at Black- 

 pool. 



With the exception of the lias and chalk specimens, the 

 coasts of Cumberland and Furness could supply nearly all the 

 rocks now found in the deposit. But how have they been 

 carried to the place where they are now met with, scored, 

 polished, angular, partly rounded, and placed on end, as they 

 now are ? Their present conditions seem to require the con- 

 joint action of glaciers and icebergs to produce them. Now 



