GEOLOGY OF THE CAMPSIE HILLS. 



31 



limestone consist of sandstone, clay, shale, 8tc. ; for 

 the natural position of all of which, see the list of 

 strata and the section. 



Iron-ore is plentifully produced in many parts 

 of this district, and it consists of two kinds. The 

 first is found in thin strata, the beds of which are 

 from four to fourteen inches thick ; and these beds 

 are separated from each other by layers of blue 

 clay strongly tenacious. The second kind is the 

 lenticular shaped or ball-formed iron-ore, which 

 is found imbedded in blue clay, and also in shale, 

 generally in the near vicinity of coal. Upon the 

 southern confines of this district, in the parish and 

 vale of Kilsyth, I examined with much attention 

 one of the mines which is remarkably productive 

 of this lenticular formed ore. I there found the 

 balls imbedded in a soft shale, and regularly ar- 

 ranged in strata ; they rest upon one of their flat- 

 tened sides, and their distribution is nearly lineal ; 

 but in these lines, they are seldom imbedded so 

 near to each other as to come in contact. The 

 balls of each line w^ere generally of the same size. 

 In the deepest strata, the largest balls are found,, 

 and the smaller-sized ones are found in higher 

 strata. The largest which I measured, somewhat 

 exceeded a foot in diameter, and they diminish 

 from this size down to a quarter of an inch. 



The interior arrangement of these lenticular 

 forms, is so well known, that no description is 

 here necessary ; they have, however, afforded a 

 field for considerable discussion, and proofs to aid 



