JF. F. Hume — JVofes on Russian Geology'. 389 



Northern Bone Bed of Kiprianov contains numerous sponges {Poro- 

 spongia, Cribrospongia concentrica) , and has referred these to the 

 Cenomanian. 



In the Chalk Marl he found Ostrea carinata, 0. canaliculata, etc., 

 and referred it to the Turonian, and finally the soft chalk with flints 

 and Belem. miicronata, 0. vesicularis, and 0. semiplana he considered 

 Senonian. (These results must, however, be modified as shown 

 above.) 



2nd. The development of the Cretaceous Basin to the west of the 

 central area may next be considered. Data from borings are very 

 scarce, the only boring of any importance being the Letunofsky 

 one, at Gorbunovka, near Poltava. The Tertiary and more recent 

 beds here attain a thickness of over 670 feet, after which 231 feet 

 of soft, white chalk was passed through. The bore was then 

 discontinued, it being concluded that the Chalk might prove to be 

 thicker than the deposit at Kharkofif. 



While a good deal of work has been lately done with regard to 

 the Tertiary deposits of the Poltava Government, no mention has 

 been made of any exposures of the Cretaceous system in that part 

 of the country. 



We must go to the neighbourhood of the town of Kieff for con- 

 clusive evidence as to the presence of Cretaceous beds on the west of 

 the Poltava Government. I am informed that a bore in the lower 

 part of the town of Kiefi" passed through 30 feet of chalk, but have 

 been unable to obtain the paper in which Prof. Theophilaktoff 

 discusses this occurrence. This bed probably soon thins out and 

 dies away at the great Archaean axis. 



Further to the south (see map) along the course of the Dnieper, 

 between Tripolie and Tcherkass, occur a series of beds of a glau- 

 conitic sandy nature, containing fossils of Cenomanian age, such as 

 Amm. Mantelli, Amm. varians, Exogyra conica, and Janira qidnque- 

 costata. These beds are 80 feet thick, and have undergone 

 considerable step faulting. The main dip is 30° S.W. that is, away 

 from the river. [It would be of interest to know whether there is 

 much trace of faulting along the course of the Dnieper, such as 

 occurs along the Thames valley. Certainly the very high escarp- 

 ment on the right side of the river, which forms such a picturesque 

 object at the town of Kieff itself, might be due in some measure to 

 such earth movements, just as there is a similar escarpment in the 

 central portion of the course of the Donetz, and also on the Volga, 

 the right bank being always the higher side.] The Cretaceous 

 sands above-mentioned are surmounted by the Tertiary sandstones 

 of Butschak and Traktemirov, whose fauna was already well known 

 in Murchison's time. A little further down the river, at Krement- 

 chug, I observed gneisses well marked on the east side of the 

 river, so that the Cretaceous deposits probably do not extend far south 

 of their known outcrop as mentioned above. These beds rest upon 

 Jurassic strata, with which they appear to be comformable. 



3rd. In a direction S.E. from Kharkoff the Cretaceous beds 

 have an enormous extension. Hidden under the Tertiary beds for 



