1897.] NATURAL SCIENCES OF PHILADELPHIA. 453 



penetrating several kilometers into the interior of the country pre- 

 sents Quaternary terraces in gentle echelons. When the confluents 

 of the Volga on the left bank unite with the major stream, their 

 valleys are merged into vast spaces like lacustrine basins which owe 

 their origin to the impeded flow of the melting snows and the strong 

 floods of spring. At the confluence with the Kama the lacustrine 

 enlargement begins in the Volga, twenty-five kilometers above 

 Laichew and extends south to Spassk and the ruins of the old town 

 of Bolgary. In the months of May and June the waters of the 

 Volga and Kama at this junction occupy a basin so extensive that 

 from a steamboat it is occasionally impossible to see the shores. In 

 these cases the level of the water is 12 to 13 meters above the normal 

 level. But in the month of August the two rivers have returned to 

 their original beds and the water level has attained its minimum. 

 It happens frequently at this season that the steamers seeking the 

 sinuous and constantly changing channels run aground. This shal- 

 lowness is most annoying toward Nijni-Novgorod and above. 



The left bank of the Volga between the Kama and Nijni-Novgorod 

 shows no older rocks. Most frequently only recent sediments are 

 seen. In some rare localities are found post-pliocene deposits, clays 

 and sands of the terraces, and between the mouth of the Kama and 

 Kazan Caspian lacustrine deposits. 



The right bank throughout the whole distance is of middle and 

 upper Permian and of Tartarian or Permo-Triassic age. The 

 middle Permian stage, the representative of the German Zech- 

 stein, is composed of limestones and dolomites, partly of oolitic 

 structure, with interstratitied beds of silex, and more or less consider- 

 able deposits or accumulations of Gypsum. This stage, which con- 

 tains almost everywhere many organic remains characteristic of the 

 German Zechstein, rises from beneath the upper stage between 

 Bogorodskoie (the mouth of the Kama) and Kozlovka (opposite the 

 mouth of the river Ilet and 30 kilometers below the town of 

 Sviajsk). The upper stage (P 3 ) or the Tartarian (PT) consists princi- 

 pally of different colored (red, pink, white, greenish and greenish 

 gray) marls, accompanied by thin beds of white limestone, variously 

 colored clays, and sandstone. This bed is very little fossiliferous, 

 and contains only some conchifers. 10 



10 Fifteen years ago the opinion was held by certain Russian geologists that 

 the beds of iridescent marls P. or PT were parallel formations with a part of 

 the beds P 2 ., with passage of the marls into these latter horizontally. Now, 

 thanks to the labors of the Geological Survey and to recent researches of the 

 geologists of Kazan, it is beyond doubt that P 2 and PT are independent stages 

 bedded the one in the other. [L. G., IX, p. 10.] 



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