40 TOWN GEOLOGY. [i. 



full. It has at some time or other been dry enough 

 to let a whole copse grow up inside it ? 



And if you found as you will actually find along 

 some English shores under the sand hills, perhaps a 

 bed of earth with shells and bones ; under that a bed 

 of peat; under that one of blue silt; under that a 

 buried forest, with the trees upright and rooted ; under 

 that another layer of blue silt full of roots and 

 vegetable fibre; perhaps under that again another 

 old land surface with trees again growing in it ; and 

 under all the main bottom clay of the district what 

 would common sense tell you ? I leave you to discover 

 for yourselves. It certainly would not tell you that 

 those trees were thrust in there by a violent con- 

 vulsion, or that all those layers were deposited there 

 in a few days, or even a few years ; and you might 

 safely indulge in speculations about the antiquity of 

 the sestuary, and the changes which it has undergone, 

 with which I will not frighten you at present. 



It will be fair reasoning to argue thus. You may 

 not be always right in your conclusion, but still you 

 will be trying fairly to explain the unknown by the 

 known. 



But have Rain and Rivers alone made the soil? 



How very much they have done toward making it 

 you will be able to judge for yourselves, if you will 

 read the sixth chapter of Sir Charles Lyell's new 

 "Elements of Geology," or the first hundred pages 

 of that admirable book, De la Beche's " Geological 

 Observer ; " and last, but not least, a very clever 

 little book called "Rain and Rivers," by Colonel 

 George Greenwood. 



But though rain, like rivers, is a carrier of soil, it 



