54 Notice of Hayden^s Geological Essays. 



or Mammoth-Thorns of deer, and other animal as well as 

 vegetable remahis, are found in many parts of our alluvial 

 districts, both near and remote from the sea; and evincing, 

 completely, that they could never have been deposited and 

 covered by any of the ordinary processes of alluvion. 



These facts, it is well known, are common to the alluvial 

 regions of other continents; and Mr. Hayden has adduced 

 many examples in relation to this part of the subject. 



The author has suggested some ingenious thoughts as to 

 the processes of petrificanon. We feel and acknowledge, 

 that there is a difficulty in accounting for the preservation of 

 animal and vegetable substances, by petrifaction or other 

 similar changes ; but as we see the process, actually going 

 on, at the present day, and some very perishable substances 

 preserved either by petrifaction or incrustation; — as at 

 Knaresborough in Yorkshire ; at the baths of St. Philip in 

 Italy, and in many other places, we perceive that the thing is 

 actually possible, and whatever may be the difficulties of the 

 subject, they appear to us less than those that attend the 

 bold assumption that petrified bodies have been invested by 

 earthy substances in the gaseous state, or that even our plan- 

 et may have been formed by gaseous emanations from the 

 sun. 



Mr. Hayden believes that, from the opposite polar re= 

 gions, there were currents which combined to produce the 

 deluge, and he conceives, that their ravages are distinctly 

 recorded in the naked and rocky state of the land in the 

 higher latitudes, of both hemispheres, the loose earth having 

 been, as he imagines, swept away and transported to other 

 regions. 



Mr. Hayden objects to the received ideas, as to the forma- 

 tion of soils and loose earth, by the decomposition of rocks, 

 which he believes to be much less extensive and rapid, than 

 has been generally imagined. This is probably true in a 

 degree, but still we cannot but think that he has underrated 

 these agencies. The decompositions, arising from the un- 

 intermitted activity of galvanic electricity, evolved by the 

 juxta position of strata and fluids of different kinds, is prob- 

 ably a potent cause, and is not, Vv'e believe, adverted to by 

 Mr. Hayden.* 



* This cause would, however, it is true, operate principally in the infe- 

 rior of the eaj'th. 



