PROCEEDINGS OF GEOLOGICAL SOCIETIES. 



411 



tude to the sea, and eastward of the 69th meridian. It includes the Serrama, 

 (as the mountainous region is termed) and the Llanos or plains to the south. 



The most ancient rocks in Venezuela consist of mica-schists and gneiss, and 

 compose the author's " Caribbian Group," 



These schistose rocks are highly distorted. In the western portion of the 

 district they have a breadth of about thirty miles, and rise to the height of 

 eight thousand feet. 



Gneiss also is present, and is markedly interstratified with the mica-schists. 

 The transition is occasionally gradual ; but more usually it is sudden and 

 abrupt. The gneiss sometimes assumes the irregular structure of granite, but 

 is still distinctly bedded. It is occasionally auriferous. Yery small propor^ 

 tions of copper-ores and argentiferous galena exist in some localities. 



The Serrama also compiises another great group of strata, flanking the 

 " Carribbian" rocks on the south, and in the eastern district rising to a height 

 of more than seven thousand feet, with a breadth of from thirty to forty miles. 

 These consist of sandstones, fossiliferous limestones, and shales, and form the 

 group provisionally termed " Older Parian." 



These Older Parian strata must be nearly eight thousand feet thick. They 

 have been intensely disturbed. Though the fossils can rarely be separated 

 from the matrix, yet some were fortunately obtained from near Cumana — 

 namely, Trigonia; and small Gasteropoda — probably of Lower Cretaceous age. 

 These Lower Parian rocks extend westward into New Granada, and are pro- 

 bably related to the Neocomian rocks of Bogota. Near their junction with 

 the " Caribbian Group" they are often interstratiEed and alternate with rocks 

 of igneous origin. 



The lilanos are entirely formed of conglomerates and sandstones referable to 

 the " Newer Parian Group," In Trinidad a lower and calcareous portion exists. 

 Altogether this group probably has a thickness of nearly four thousand feet. 

 Possils are abundant in the calcareous division, and seem to represent the 

 Lower Pliocene or Upper Miocene series of Europe, 



The upper portion of the Newer Parian series, which is often shaly, contains 

 beds of lignite, frequently admitting of exploitation. The lignite occurs at 

 several localities on the mainland, and also in Southern Trinidad, The ligniti- 

 ferous beds have locally undergone combustion to a great extent, from natural 

 causes, such as the decomposition of pyrites. The result is that the strata 

 have been indurated and baked for a vertical extent sometimes of seventy or 

 eighty feet, the clays assuming various conditions, and presenting the "porcel- 

 lauites" and " therm.antides" of continental authors. 



The asphalt of Trinidad and the mainland is almost invariably disseminated 

 in the upper part of the Newer Parian group. When iti sitic, it is confined to 

 particular strata, which were originally shales containing a certain proportion 

 of vegetable debris. The organic matter has undergone a special mineraliza- 

 tion, producing a bituminous, in place of the ordinary anthraciferous sub- 

 stances. This operation is not attributable to heat, nor of the nature of dis- 

 tillation ; but is due to chemical reaction at the ordinary temperature and 

 under the normal conditions of the climate. After the solution and removal 

 of the bitumen from wood passing into asphalt, the remaining organic structure 

 presents peculiar appearances under the microscope. 



The occurrence of asphalt in New Granada and the Valley of the Magda- 

 lena in all probability indicates the presence of the Newer Parian strata in 

 those districts. 



2. " On the co-existence of Man with certain Extinct Quadrupeds, proved 

 by Eossil Bones from various Pleistocene Deposits, bearing Incisions made by 

 sharp instruments." By M. E. Lartet, Eor. M.G. S. In a letter to the President. 



The author having for some time past made observations upon fossil bones 



