Geological Society of London, 575 



across, surrounded by a sahlband, and consists of granular iron 

 pyrites, with a very small mixture of copper pyrites, some silica, 

 and traces of lead and zinc, and covered near the surface with a 

 thick gossan, varying from 20 to 160 feet. It is worked at five 

 localities — St. Domingo, Tliarsis, Coronada, Rio Tinto, and Buitron. 

 At the latter place it is estimated that there are 4,000,000 tons of ore 

 above the level of the present adit. 



Geological Society of London. — Nov. 11th, 1868. — Prof. T. 

 H. Huxley, LL.D., F.R.S., President, in the chair. 1. '' Note com- 

 paring the Geological Structure of North-western Siberia with that 

 of Russia in Europe." By Sir R. I. Murchison, Bart, K.C.B,, G.C 

 St.S., F.R.S., Y.P.G.S., &c. 



Count A. von Keyserling had communicated to the author the 

 following facts : — The district between the rivers Lena and Jenissei 

 is occupied by Upj)er Silurian rocks of the same type as those found 

 in the region of Petchora, and by Carboniferous rocks containing 

 seams of coal. The chief Secondary deposits are of Oolitic or 

 Liassic age, and agree with those of the Petchora region, which is 

 the next adjacent tract on the west to the Siberian region in ques- 

 tion. Similar rocks are found in Spitzbergen. The banks of the 

 Jenissei are covered with Post-pliocene accumulations similar to 

 those found near Archangel. It is thus seen that the vast, slightly 

 undulating, and to a great extent horizontal and unbroken forma- 

 tions, each of which occupies so wide an area in European Russia, 

 are repeated on the eastern side of the Ural Mountains. In this 

 range of mountains only are to be found igneous and erupted rocks. 



In conclusion, Sir Roderick referred to the discovery of fossili- 

 ferous white Chalk in parts of the great Sarmatian plain by M. 

 Grewinck. 



Discussion. — Sir Roderick Murchison, in explanation of the paper, 

 referred to a geological map of Russia, and gave a general sketch of 

 the bearing of the paper on the previously known geology of that 

 country. He mentioned the discovery by M. Grewinck of beds of 

 brown coal containing amber, and overlying true Chalk. The amber 

 in the Baltic had been supposed to have been washed out of beds 

 beneath the sea ; but Count Keyserling has suggested that the 

 amber may have been brought down by the rivers from the interior, 

 and deposited in the Baltic. Sir Roderick also called attention to 

 the absence of igneous rocks in Russia to the west of the Ural 

 Mountains. 



2. " On a section of a Well at Kissingen." By Prof. Sandberger, 

 For. Corr. G.S. 



Taking as a starting-point a bed of dark-blue limestone, the author 

 proceeded to describe the various beds passed through in sinking the 

 Schonbern well, both as regards their petrological characters and 

 chemical constitution. He considered that this bed is on the same 



