■;4 Geological Dclinpation of South America, 



'cvspcrscdin this sandstone. The shells themselves arc half 

 broken : whole rocks consist merely ot" such remains re- 

 duced to powder. Mv fellow-traveller, Bonpland, discovered 

 in them shells of the genus I'iima,. \'enus, and OstFea, of 

 which living specimens are still met with on that coast; an 

 obscrvation'of great importance to gcofogy. Every thing 

 shows that this stratum, which 1 have seen only at the di- 

 stance of nine or ten miles from the present- coast, is of very 

 modern origin, and that the lluid in which it was produced 

 had been in a state of violent motion, 'ihc petrified sliells^ 

 in a nu(ch older stratun\ of compact limestone are scarcer 

 -md inuch dittcrently stratified : they aie anonVia, terebFatu- 

 Tites, Sec. placed together in families^ and in such a manner 

 that it is seen that thev have lived (as those of Mount 

 .SalivCj'lhe Heinbcrg near (juttingen, of Jena, and Geneva) 

 on the spot where they are now ibund petrified, 'i'hcv are 

 not iuterLfpcrscd throughout the v.'hok mass of the lime- 

 stone ; they arc only peculiar to certain strata. Many roek& 

 may be examined without finding any of these petrifactions j 

 bnt where found they are in great quantity, and present 

 themselves ehiefiy on great h.cighls ; peculiarities which 

 tiicv have in connnon with the shells found in the lime- 

 stone of the high Alps of SwisscHand and Salzburg, which 

 is identic with ihe hardened nsarl of Thuringia, a limestone 

 v>hich lies above the vcrv old sandstone. 



I must observe also, that, besides the new sandstone 

 stratum with a calcareous base, of which 1 have already 

 spoken, the petrifactions do not often occur ; and I was 

 particularly astonished to find no single belemnites or am- 

 monites which are so common in all the mountains of 

 Huropc. The Llano of Orinoco, and that even of Kio 

 Negro, are covered with a coarse grained breccia {nagel- 

 Jiuhf) which contains no petrified shells, and perhaps covers 

 the other alluvial strata with petrifactions. But this breccia 

 contains on the other hand petrified trunks of trees, which 

 .ire sometimes luund of the lengtli of a toise, and of the 

 diameter of two feet. They seem to belong to a kind of 

 Malphigia. 



The sandstone which contains all kinds of marine ani- 

 mals (the quarry of Punta del Barrigon near Arayais of this 

 sort) never exceeds the height of from 30 to 40 toises- In 

 several places it forms the bottom of the Gulph of Mexico 

 (Cabo Blanco, Punta Araya). In the compact limestone I 

 never saw petrified shells above the height of 800 toises ; 

 but other verj- new^ testimonies prove the residence of the 

 vvaicr at much greaicr heights. Slate found on the Silla de 

 ■^ Caracas, 



