OF CLACK MAN AN SHIRE. 



composed of a mixture of fine sand and clay, and 

 adjoining the hill-foot, it is very much mixed 

 with stones. Shells of the mya, or fresh-water 

 mussel, are found in it, and also trunks of oak 

 trees. One of these oaks, of very great size, is to 

 be seen north from the Devon iron- works. 



The depth of this soil has not been ascertained, 

 as no pits or bores have been put down in the line 

 of section. From the south boundary of the re- 

 cent alluvial soil of the Devon, to the north 

 boundary of the recent alluvial soil of the river 

 Forth, the rock cover is composed of a stiff red 

 coloured clay, commonly known by the name of 

 Till. It does not seem to follow any general rule 

 as to thickness. In this district, the swelling 

 arable ground south of the Ochills is frequently 

 entirely composed of this till; but this is not 

 without exceptions. We have seen it in thickness 

 from one foot to a hundred and sixty-two feet. 

 This uncommon depth or thickness occurred in 

 the rising ground immediately north from the 

 town of Alloa. 



With respect to the composition of this cover, 

 it appears to be of clay, with sand intimately mix- 

 ed, so as to render it quite impervious to water : 

 with these are mixed great numbers of small 

 smooth stones, such as occur in the beds of river?, 

 and also large smooth boulder-stones, of every co- 

 lour, known by the general name of Whinstone, 

 Besides this mixture, there are to be found a great 



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