icith Geognostical Observations, <SfC. 133 



horizontal stratification of this rock appears. Upon this hill, 

 not far from Mahomet Kourgan, whence we discover the val- 

 ley of Baksan on the Haimacha, we at last see the sandstone 

 rise with a calcareous rock on which it rests, and which is the 

 oldest secondary limestone of the Caucasus. In the valleys of 

 Kichmalka and of Kassaout we have met with a sandstone, 

 which, in the series of superpositions, ought to be the same as 

 the sandstone with ostracites; it is, however, entirely devoid 

 of fossils. In the valley of Kassaout, it is very compact at 

 places on a lower level, where it sometimes contains strata of 

 argillaceous schistus. It is very quartzy at the same place, 

 and does not effervesce with acids, while on the heights it is 

 much mixed with carbonate of lime. 



In an excursion in which we went out of the valley of Kas- 

 saout, in advancing towards the central chains to seek for a 

 lead mine which the Tsherkesses had mentioned to us, we met 

 on the heights which we traversed a very coarse conglome- 

 rate ; rounded peebles of common white quartz, grey brown 

 and black jaspers, and some fragments of argillaceous schistus, 

 are all imbedded in a quartzy cement. 



In spite of the most careful examination, I could not find 

 any fragment of trachyte in this conglomerate. 



When we have reached the boundary of this plateau, we are 

 still separated from the central chain by a wide and deep val- 

 ley, and it is while descending a little towards this valley that 

 we suddenly meet with nearly vertical strata of a particular 

 rock, against which the above-mentioned conglomerate appear- 

 ed to lean. We soon discover ancient works for obtaining the 

 particles of sulphuretted lead disseminated in the rock. In 

 the parts near the conglomerate this rock is also composed of 

 pieces of rolled quartz, cemented by a very ferruginous clay, 

 (not far from this is found much ochre of yellow iron,) in other 

 places the relative quantity of the pieces of quartz diminishes, 

 the paste predominates, and we see it distinctly composed of 

 two substances, feldspar and sulphate of barytes ; it is also the 

 sulphate of barytes which forms the gangue of the sulphuret 

 of lead, and the thin strata of it are traversed by narrow veins 

 of the compact sulphurels of lead and antimony, grey copper, 



