GENERAL INFERENCES. 89 



If the rocks of Dura Den were formed during the epoch of 

 such violent agencies, we, therefore, conclude that the fishes 

 now embedded in their consolidated materials were suddenly 

 destroyed by one of the disturbances of the period, and that 

 their position as confined to a single bed furnishes an additional 

 proof of the rapid collection and silting up of the materials of 

 which the rocks themselves are constituted. Leibnitz, in his 

 Protogeia, has largely dwelt upon these points, which, although 

 geology in his time was in no w^ays systematized, are remark- 

 ably in harmony with the deductions of modern discovery ; in 

 his masterly sketch, especially of the leading geognostic canons 

 of the science, he successfully advocates the intensive energy 

 with which physical causes must have acted in primordial 

 times ; and considers that the disruptions and igneous accumu- 

 lations of the earth's crust, from the disturbances communicated 

 to the incumbent waters, must have been accompanied with 

 diluvial action, the maxim ce secutce inundationes, on the largest 

 scale and the most extensive results. 



6. But upon any view of these interesting speculations, a 

 terrestrial flora, on a scale of magnitude incomparably greater 

 than any in modern times, was now preparing for economic 

 purposes, the uses and the wants of creatures yet to emerge in 

 long after-periods. The dense forests that were to supply the 

 materials of our coal-fields, and the heaths and other herbaceous 

 shrubs that w^ere to secrete the metal in our ironstone, required 

 an extent of jDlains, uplands, and mountain slo{)es which must 

 have surpassed in extent all existing carse, strath, or highland 

 glen in " Caledonia wild," or anywhere in the British Isles. 

 The seas likewise w^ere to undergo mighty changes, both in 

 their deep oceanic troughs and their more shallow littoral ar- 

 rangements. Submarine volcanoes, whose poisonous elements 

 destroyed these shoals of ganoid fishes, were now to eject 

 volumes of calcareous and muddy materials, out of which coral- 

 agency was to elaborate the mountain limestones, and in whose 

 soft banks the countless shell-fish of the period were to burrow. 



