JN THE MUD OF THE LEVANT. 99 



instance, near Clermont, where this process is 

 still going on, the lime being partially dissolved 

 and rendered soft, — the quartz alone remaining 

 unattacked.* Carbonated water has, in all pro- 

 bability, produced some of the changes which the 

 calcareous organisms of strata still retaining much 

 carbonate of lime, but without any visible organic 

 structure, have undergone. 



The pisolitic structure of many Oolitic rocks 

 has been referred to. It occurs more commonly 

 than is generally imagined. Sir R. I. Murchison 

 found it in extensive Miocene deposits in Southern 

 Russia. Similar appearances are presented by 

 beds of the same age in Styria and Hungary.f 

 It is more or less common amongst all the 

 Oolitic strata, and is seen in the Carboniferous 

 rocks of Indiana, U.S. 



On examining; thin sections of oolitic lime- 

 stone from Bristol, Durdham Down, Yorkshire, 

 and Skerry, I found that the granules in these 

 specimens, composed of the well-known concentric 

 layers, were imbedded in a crystalline matrix. 



* Principles of Geol. Vol. i. p. 317. Second Edition, 

 t Annual Address to the Geol. Soc. By Leonard Horner, 

 Esq. 1846: p. 49. 



