646 



B O L C A. 



Bolca. friction on every part of the stone, is considered a 

 "" v ' strong presumption also, that its whole substance has 

 absorbed a great proportion of animal matter. 



Admitting the truth of the general principle, on 

 which these theories are founded, there are still many 

 difficulties to be surmounted, and one of the most 

 important lies in the structure of Bolca. This hill is 

 not a homogeneous mass; it consists of various sub- 

 stances, in unequal proportion, and forming four 

 classes, according to geologists, among which are 

 marl, spar, basalt ; coal and amber ; pyrites and he- 

 matites ; marine plants, insects, fishes, and the re- 

 mains of terrestrial animals in a state of petrifaction. 

 The petrified, substances do not lie in horizontal 

 strata; horizontal so far as would result from the 

 deposit of pulverised matter on an uneven surface ; for 

 the masses of stone wherein they are contained are 

 imbedded in the sides of the hill : they seem de- 

 tached and apart from the other parts composing it, 

 and rest in various degrees of inclination. But per- 

 haps this may be accounted for, by supposing, that 

 subsequent to their formation, they were exposed to 

 some violent disturbing cause, which affected their 

 original position. There is no necessity that such 

 disturbing cause should have approached tlie a;ra of 

 their formation ; on the contrary, appearances indi- 

 cate that it has existed at a time very remote from it. 

 If the fishes were suddenly destroyed by some perni- 

 cious vapour, absorbed by the water where they 

 swam, or by some lethal quality otherwise imparted 

 to it,^ they must have remained for ages in their ori- 

 ginal state. The open mouth and distended fins ex- 

 hibited by them, naturalists have conjectured denote 

 immediate suffocation ; after which they were invol- 

 ved by the component matter of the stones contain- 

 ing them, and themselves converted to stone. But 

 that the deposit was made on a surface at rest, is 

 evinced by the laminar structure of all the strata ; 

 their whole leaves are parallel to each other, and per. 

 fectly flat ; where their continuity is interrupted, the 

 extremities are sharp and cleanly cut off, as if by frac- 

 ture in their horizontal position. Though the time 

 requisite for complete petrifaction is unknown, we 

 may presume that it is slowly accomplished ; and if 

 we are to credit the correctness of an observation, 

 that in 1500 years wood was not affected above a 

 quarter of an inch in depth, the period must almost 

 exceed the bounds of calculation. Therefore it is 

 not unlikely that two great epochs are to be counted 

 in the formation of Mount Bolca and its singular 

 fossils : first, that which occasioned the sudden de- 

 struction of an infinity of living beings, and their un- 

 disturbed envelopement and investiture at the bottom 

 of the sea, by the substance diffused; and secondly, 

 the disturbance of that deposit from its original level, 

 which may probably have been accomplished by 

 some violent convulsion of the earth. But the one 

 may have followed the other at an immense interval 

 of time. Had it happened soon after the animals in 

 question perished, their tender and corruptible sub- 

 stance would have soon been so essentially altered, as 

 to preclude all possibility of recognising them at the 

 present day. Surely we need not anticipate objec- 

 tions from the force required to implant the huge 

 calcareous masses in the sides of Bolca. If rocks are 



projected from burning craters, mountains raised, or 

 islands formed in unfathomable seas, what power is 

 there which violent convulsions of the earth are un- 

 able to overcome ? 



The curiosities afforded by Bolca, had, centuries 

 ago, attracted the notice of ingenious and speculative 

 minds; and thence the peasantry and labourers of the 

 neighbourhood have gained a livelihood by procuring 

 them. Blocks of moderate size are detached from 

 the face of the quarries ; and being brought out and 

 set on edge, are split asunder with sharp hammers or 

 wedges. The workmen then examine the leaves, to 

 discover whether there be organic remains of fishes 

 or other substances ; and should they discover any 

 such, which are generally shattered from the rude- 

 ness of the operation, they collect them with the 

 greatest care : the pieces also that adhere to the 

 stone, are cautiously separated from it. When their 

 daily occupation is completed, the workmen carry 

 the collections they have made to their own houses, 

 where they are- kept until delivered to their employers 

 in Verona. The pieces are taken thither in baskets, 

 and either given to the owner of the soil, or privately 

 sold to dealers in such productions, or to naturalists 

 desirous of acquiring them. It is said that the pur- 

 chaser, who obtains the fossils in this state from the 

 workmen, is then obliged to employ a skilful lapidary 

 to search out and arrange the pieces composing each 

 specimen, and cement them on another stone of the 

 same kind. So much art and accuracy are some- 

 times used in doing this, that it is scarcely possible to 

 discover the places of junction ; and it is thus that 

 the specimens are prepared for sale, or for cabinets. 

 As a greater or less proportion of the brown matter 

 of the bones, fins, and other parts of fishes, some- 

 times adhere to one side in splitting the stone, and 

 sometimes to another, or is frequently divided be- 

 tween both, the more valuable specimens consist of 

 duplicates ; for when the pieces are well and skilfully- 

 put together, their prominences correspond with the 

 cavities in the opposite half. Most of the specimens 

 hitherto extracted have come from one principal 

 quarry in the side of the hill, called Pescaia by the 

 inhabitants of that territory; but there are several be- 

 sides, supposed to be of later discovery, all equally 

 abounding in petrifactions. The people, however, 

 who attempted to form excavations being poor, and 

 no funds being specially appropriated for this curious 

 research, which would have been attended with con- 

 siderable expense, nothing important followed. The 

 soil where the quarries lie, has belonged to different 

 owners, who were solicitous to obtain its contents. 



The variety and singularity of the fossils discover- 

 ed on the surface and in the recesses of this hill, af- 

 ford so much scope for philosophical contempla- 

 tion, that unusual care has been taken to collect and 

 preserve them. Extensive cabinets, from which all 

 other varieties were excluded, have thence been form- 

 ed of them alone ; and these have passed into the 

 hands of successive owners, along with a right to ex- 

 plore the soil, in the same manner as we are wont to 

 transfer the richest territorial property. The first 

 cabinet of the productions of Bolca with which we 

 are acquainted, was collected by a person distinguish- 

 ed in the pharmaceutical art, Francesco Calceolari, 



Bolca 



