Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/318

 the complete history of one of these accumulations. A pool of water is peopled by myriads of little animals, with whose exuviæ 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 exuviæ, 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 marle is not common to all the Scotch lakes, it might be worth inquiry what peculiar circumstances favoured its production; 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, distant 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 pudding stone. Whin-dykes, and veins of barytic spar, occasionally tinged