between Arch(Bology and Geology. 239 



retaining a large proportion of animal matter, as are those of 

 the moa, Irish elk. and mastodon, found in morasses and 

 turbary deposits ; or they may be permeated by carbonate 

 of lime and have the medullary cavities lined with spar, like 

 the bones of Carnivora found beneath the stalactitic floors of 

 caverns ; or petrified by solutions of iron or other minerals, 

 as are the remains of the extinct quadrupeds in many of the 

 tertiary limestones, and those of the colossal reptiles in the 

 Wealden deposits. They may also be invested with stalactite 

 if buried in fissures or caves of limestone ; or with travertine 

 if exposed to the action of streams highly charged with car- 

 bonate of lime, like the so-called petrifying springs of Derby- 

 shire ; or impacted in ferruginous conglomerate, if deposited 

 with implements of iron, or in a soil charged with chalybeate 

 waters ; and these effects may be produced in the course of 

 a very brief period ; — a few years, or even months, will often 

 suffice for the formation of a compact, durable mass, in which 

 bones, pottery, and coins, and other substances may be 

 imbedded. 



Although^instances of such productions must be familiar 

 to every antiquary, it may be instructive to notice a few 

 examples that have come under my own observation, be- 

 cause they serve to illustrate the nature and origin of certain 

 specimens, which have been regarded by authors of deserved 

 celebrity as genuine petrifactions, of immense antiquity. Thus 

 the eminent mineralogist, Kirwan, quotes from Schneider's 

 " Topog. Min." — " that one hundred and twenty-six silver 

 coins were found enclosed in flints at Grinoe, in Denmark, 

 and an iron nail in a flint at Potsdam."* The first edition 

 of Mr BakewelPs Introduction to Geology,t contains the 

 following circumstantial narrative by Mr Knight Spencer. 

 "In 1791, two hundred yards north of the ramparts of 

 Hamburgh, in a sandy soil, M. Liesky, of that city, picked 

 up a flint, and knocking it against another, broke it in two ; 

 in the centre of the fracture he observed an ancient brass 

 pin ; and on picking up the other half, he found the corres- 



* Phillips's Mineralogy, 2d edit., Article Flint, p. 12. 

 t Published in 1813, p. 338. 



