308 Mr. Warburton on Shell-Mark. 



the complete history of one of these accumulations. A pool of 

 water is peopled by myriads of little animals, with whose exuvise it 

 becomes gradually filled, and thus beds are raised and fitted for 

 vegetation. Water and land plants arise and decay, and in a humid 

 soil a peat bog is formed ; perhaps (as has happened at Logie) the 

 outlet of the water is again choaked, and the same effects renew in 

 the same order. 



The calcareous beds thus formed are, it is true, on a small scale, 

 when compared with those of the Paris or Hampshire basins. Yet 

 contrasting the insignificance of these little testaceous animals with 

 the space occupied by their exuviae, which at Lundie, for instance, 

 is many feet deep and covers an area of seventy acres, the extent 

 of their beds is surprising. The siliceous beds indeed, and the 

 porcelanic limestone of the Paris basin are wanting to this recent 

 formation, and are still problems for geologists to solve ; but in 

 respect of the quantity of shelly matter the analogy is perfect, and 

 the imagination can readily seize the effects produced in a warm 

 and prolific climate with animals of decuple dimensions, and with 

 a liberal allowance of time. 



Since shell marie is not common to all the Scotch lakes, it might 

 be worth inquiry what peculiar circumstances favoured its pro- 

 duction ; whether calcareous salts are particularly abundant in the 

 waters that yield it ; and what are the rocks from which those 

 waters spring, or which form the sides of containing basins. The 

 water of Resteneth is said to be remarkably clear. 



There is no limestone near to Logie, except in a small vein, dis- 

 tant therefrom two miles, at Readie in the parish of Airlie. The 

 predominant rock about Resteneth is a sandstone of a brown, red, or 

 whitish grey colour, which alternates with a coarse ferruginous pud- 

 ding stone. Whin-dykes, and veins of barytic spar, occasionally tinged 



