WORK OP RUSSIAN INVESTIGATORS 71 



epicycles or divisions of tlie present cycle of erosion since the first up- 

 arching of the nearly completely planed mountains of the previous cycle. 



EussiAN Work 



The indefatigable labors of the Russian geologists, notably Karpinsky, 

 Tschernychew, Pavlov, and Nikitin, have brought out the succession of 

 strataand the geological structure of Russia in so many localities that 

 it is now possible to understand the main structural features of the 

 country and to make out much of the physiographic history of eastern 

 Europe. The work of the Geological Survey of Russia was so far ad- 

 vanced in 1892 that a geological map of European Russian was pub- 

 lished. It was slightly amended and added to in the edition of 1897, 

 and this generalized statement gives one a graphic picture of the great 

 geographic features of Russia, the scale of the maj), 1 : 2,520,000, being 

 just right to bring them out, though too small to show details. The 

 topographic maps of Russia, on the scale of 1 : 420,000. are not so good 

 as those of most other European countries, and they do not add much 

 to the conception of land forms obtained from a study of the geologic 

 maps. 



The two great plains — that of central Russia and that which occupies 

 nearly the whole of Siberia — stand out in marked contrast to the smaller 

 surrounding areas of mountains. Central Russia is made up of nearly 

 horizontal deposits from the Permian rocks down to those made by the 

 recent rivers, as they baselevel the country by cutting their right banks 

 and depositing the waste on their left banks. Many of these horizontal 

 deposits are marine, though there have been several periods of land 

 conditions, as, for exam pie, the Triassic or the Recent. This whole region, 

 as shown by its deposits, has oscillated back and forth near sealevel ; 

 now a little above and now a little below. The Siberian plain presents 

 a vast expanse of Tertiary accumulation. 



In contrast with this plain structure of central Russia are four areas 

 of mountain structure, each cut off from the others by large bodies of 

 water. Beginning on the north is the baseleveled area of the old moun- 

 tains of Finland, separated from the Urals by the Arctic ocean. On the 

 west come the Baltic sea and the Carpathian mountains, with their vari- 

 ous outliers, including the old mountains west of Kiev, which are thor- 

 oughly planed down and now almost completely covered with Tertiary 

 deposits. On the south are the Black sea and the Caucasus mountains, 

 while on the east are the Caspian sea and the Ural mountains. The 

 problems of the Caucasus, the Carpathians, and the old mountains of 

 Finland are not discussed in this paper, attention being given only to 



