386 H. E. Strickland, Esq., on the Geology 



The formation may be described as a mass of argillaceous schist, compact 

 brown sandstone, and compact dark blue limestone, passing into each other 

 by insensible gradations. The argillaceous schist predominates greatly over 

 the other two rocks, and frequently exhibits an oblique or slaty cleavage. 

 The whole formation bears a close analogy to the lower Silurian and upper 

 Cambrian series, exhibited in Wales and Devonshire. From its resemblance 

 to the type of northern Europe, Andreossy* and an American travellerf re- 

 ferred it to the transition series on mineralogical grounds alone ; and this 

 opinion is now confirmed by the discovery of organic remains, analogous to 

 those of the Silurian rocks of Britain. This fact is interesting, from the ex- 

 treme rarity of fossils in deposits of this early age in the southern parts of 

 Europe. 



The stratification of these rocks is in general much disturbed and con- 

 torted ; and in other cases it is very obscure and difficult to detect. Hence 

 it would require a closer examination than I was able to give, to establish the 

 prevailing strike of the formation. 



Organic remains appear to be extremely local, and were noticed in only 

 two localities. The first of these is in the ravine above Arnaout-keui, a vil- 

 lage about four miles from Pera, on the European side. The rock is an argillo- 

 calcareous schist, splitting at an angle, oblique to the stratification. Impres- 

 sions of various Brachiopoda and joints of Crinoideae occur in it, lying in the 

 planes of stratification. The substance of the shells has perished, leaving a 

 brown dust; and the casts are in general much distorted by the compression 

 and consolidation of the strata. 



These remains were first noticed by M. Fontanier;};, who mistook the shells 

 for Pectines, and thence inferred that this was a secondary formation. Had 

 he examined them with more care, he would probably have agreed with AJ. 

 Andreossy, who, without the assistance of organic remains, referred these 

 rocks, as already stated, to the transition era. 



The only other locality, where organic remains were seen, is on the hill called 

 the Giant's Mountain, on the Asiatic side of the Bosphorus, about fifteen 

 miles from Constantinople. It is singular that of three authors (Andreossy, 

 Fontanier, and the author of " Sketches of Turkey"), who have noticed with 

 more or less exactness the geology of this hill, not one has remarked the nu- 

 merous and interesting fossils which occur there. 



The lower part of the hill consists of compact limestone, thickly bedded, of 



* Memoire sur le Bosphore. 8vo. Paris. 



f Sketches of Turkey, by an American. New York. 8vo. 1833. 



% Voyage en Asie Mineure. Paris. 8vo. 



