6 GEOLOGICAL MEMOIRS. 



the ocean, but was a constituent part of the great Arabio-Ponto- 

 Caspian or mediterranean lake. At one place the boundary of its 

 basin is decidedly known, and has been described by Herr Stur *, 

 who states that " the dividing-line of the pleistocene plateaux is not 

 only such a one for the Rivers Bug and Dneister, but it is at the 

 same time part of the great dividing-line between the Black Sea and 

 the East Sea. South of this limit all the strata are covered by Loess, 

 while north, on the plain, sand, black soil, and erratic blocks are 

 spread. The same dividing-line acted as such even previously to 

 the Pleistocene period." The lowland of Hungary was a great bay 

 of a Pleistocene lake, and was connected with it by the " narrows " 

 (or " straits ") of the Iron-gate, in the same manner as the Euxine 

 is, by the Bosphorus, connected with the Sea of Marmora. 



The author then enters into the details of the configuration of the 

 bottom of this lake, of which some remains are to be met with. 

 Such are certain hills, commonly called tumuli, but of which only a 

 small number are real tumuli, the greatest number being geological 

 mementos of the Pleistocene period. He is acquainted with about 

 130 tumuli erected by man, but with above 600, in Hungary alone, 

 which have been formed by successive depositions of the same strata 

 as those which form the lowland of that country. The left bank of 

 the Theiss may be considered a classical ground for the study of 

 these remarkable formations. Guided by the geological tumuli, and 

 the law of their distribution, he points out that the original depres- 

 sions are remains of the bottom of the Loess-lake, and of the depres- 

 sions formed subsequently by denudation. This statement refers 

 especially to one of the bays of the Pontic depression, and perhaps 

 has a further bearing upon the question of the probable form of the 

 bottom of the Pleistocene lake. 



Three great depressions may be distinguished, which were divided 

 by two longitudinal elevations. Of those basins the middle (the 

 Caspian) was the deepest. The water of the lake having been by 

 some means carried off, the dividing-lines were rendered dry ; and 

 they act as natural barriers between the basin of the Aral and the 

 Caspian Seas on the one side, and between the basin of the latter 

 and that of the Euxine on the other, to the present day. The level 

 of the Caspian is reported as being, in some places, only 23 feet 

 above the level of the Black Sea. 



Inauguration of the Recent Period. — Having sufficient proof that 

 the Loess, notwithstanding its local uniformity, is in most cases 

 stratified, it follows that it was deposited in water, and was not the 

 result of any form of ice-action ; and, the strata being nearly hori- 

 zontal, the water must have occupied the adjacent depression of 

 Europe and Asia after the formation of the general configuration of 

 the territory. 



The general outline of the land was formed during the period of 

 the trachytic and basaltic eruption which also destroyed the Congeria- 

 sea. The end of this period is marked by great movements of 



* Jahrbuch der k. k. geol. Reichsanstalt. Wien, 1860 (On the Pleistocene 

 Plateaux in Gallicia). 



