312 Supplement to the Comparative Estimate 



from above, would shoot out in branches of similar stalagmite, in 

 striving to percolate downwards through it ; or, if the mud were 

 firm enough to support it, would form a crust on its surface. In 

 the mean time, the animal substances, occupying the interior of 

 the cave, would continually diminish by decomposition, and hav- 

 ing been defended by their integuments from rolling or trituration 

 during their transport, and from the time of their Hist immersion, 

 such portions as had not decayed and perished, would neces- 

 sarily exhibit surfaces wholly untriturated ; moreover, because all 

 the bodies were immersed simultaneously, in one vast united mass, 

 no alternations of animal and mineral matter could have taken place. 



Crevices and fissures in cavities lying near the surface would na- 

 turally be produced by the drying of a mineral paste saturated 

 with wafer, and suddenly and permanently exposed to the action 

 of air and heat ; or, if the enclosed bodies were in very large num- 

 bers, the gases evolved by their decomposition might have dis- 

 tended the soil of the sides whilst yet soft and yielding, and even 

 have forced their way through the weakest part, so as to form 

 channels and orifices bearing no geometrical proportion to the ori- 

 ginal bulk of the bodies themselves. 



"This operation, and its general effect upon the bodies, would 

 only be a vast enlargement of that which we so commonly witness 

 on a minute scale, in limestone rocks containing shells. In those 

 rocks, in consequence of a similar process of exsiccation producing 

 contraction and compression of the mineral mass, we sometimes 

 observe the shells to be broken, sometimes altogether crushed, and 

 sometimes again entire and freely moveable within their little 

 cavities ; and we often perceive the sides of those cavities to be 

 coated with small crystals produced by the filtered fluid, as in the 

 large cavities by stalactite. Now ' that which is so readily ima- 

 gined on a small scale,' observes justly Dr. Mac Culloch, ' is as ea- 

 sily transfcred to a larger ; since, in the operations of nature these 

 terms are of no moment* .' We obtain, therefore, from what has 

 been here exposed, a strong philosophical probability that the ac- 

 cumulated and mingled masses of tropical and other animals, 

 whose bony fragments have been found in Germany and in Eng- 

 land, assembled in vast congeries in the interior of one and the 

 same class of secondary rocks; containing also in their substances, 

 in numberless instances, fragments of shells and other marine organic 

 remains ; were there enveloped, after transportation and deposition, 

 by the substance of the rock during its pristine state of fluidity in the 

 bottom of the primitive sea: just as the shell was unquestionably 

 involved by the same substance during its pristine state of fluidity, 

 and in no other manner ; that the cavity in which they are found, 

 was originally moulded upon the general surface of the aggregated 



* Geologicai Description of the Western Islands of Scotland, vol. ii. p. 10. 



