60 TOWN GEOLOGY. [n. 



by, or altered by volcanic heat,, and almost all found in 

 the Lake mountains), 37 per cent. 



Silurian grits (the common stones of the Lake 

 mountains deposited by water), 43 per cent. 



Ironstone, 1 per cent. 



Carboniferous limestone, 5 per cent. 



Permian or Triassic sandstones, i.e. rocks imme- 

 diately round Liverpool, 12 per cent. 



Now, does not this sample show, as far as human 

 common sense can be depended on, that the great 

 majority of these stones come from the Lake 

 mountains, sixty or seventy miles north of Liverpool ? 

 I think your common sense will tell you that these 

 pebbles are not mere concretions ; that is, formed out 

 of the substance of the clay after it was deposited. 

 The least knowledge of mineralogy would prove that. 

 But, even if you are no mineralogist, common sense 

 will tell you, that if they were all concreted out of the 

 same clay, it is most likely that they would be all of 

 the same kind, and not of a dozen or more different 

 kinds. Common sense will tell you, also, that if they 

 were all concreted out of the same clay, it is a most 

 extraordinary coincidence, indeed one too strange to be 

 believed, if any less strange explanation can be found 

 that they should have taken the composition of 

 different rocks which are found all together in one 

 group of mountains to the northward. You will surely 

 say If this be granite, it has most probably come 

 from a granite mountain ; if this be grit, from a grit- 

 stone mountain, and so on with the whole list. Why 

 are we to go out of our way to seek improbable 

 explanations, when there is a probable one staring us 

 in the face ? 



