THE PROGRESS OF GEOLOGY 411 



secondary causes; as if the death of some individual in 

 whose fate they are interested happens to be accompanied 

 by the appearance of a luminous meteor, or a comet, or the 

 shock of an earthquake. It would be only necessary to 

 multiply such coincidences indefinitely, and the mind of 

 every philosopher would be disturbed. Now it would be 

 difficult to exaggerate the number of physical events, many 

 of them most rare and unconnected in their nature, which 

 were imagined by the Woodwardian hypothesis to have 

 happened in the course of a few months: and numerous 

 other examples might be found of popular geological theo- 

 ries, which require us to imagine that a long succession of 

 events happened in a brief and almost momentary period. 



Another liability to error, very nearly allied to the former, 

 arises from the frequent contact of geological monuments 

 referring to very distant periods of time. We often behold, 

 at one glance, the effects of causes which have acted at times 

 incalculably remote, and yet there may be no striking cir- 

 cumstances to mark the occurrence of a great chasm in the 

 chronological series of Nature's archives. In the vast inter- 

 val of time which may really have elapsed between the 

 results of operations thus compared, the physical condi- 

 tion of the earth may, by slow and insensible modifications, 

 have become entirely altered; one or more races of organic 

 beings may have passed away, and yet have left behind, 

 in the particular region under contemplation, no trace of 

 their existence. 



To a mind unconscious of these intermediate events, the 

 passage from one state of things to another must appear so 

 violent, that the idea of revolutions in the system inevitably 

 suggests itself. The imagination is as much perplexed by 

 the deception, as it might be if two distant points in space 

 were suddenly brought into immediate proximity. Let us 

 suppose, for a moment, that a philosopher should lie down 

 to sleep in some arctic wilderness, and then be transferred 

 by a power, such as we read of in tales of enchantment, to a 

 valley in a tropical country, where, on awaking, he might 

 find himself surrounded by birds of brilliant plumage, and 

 all the luxuriance of animal and vegetable forms of which 

 Nature is so prodigal in those regions. The most reasonable 



