2 GEOLOGICAL MEMOIRS. 



and consequently flooded a larger area. The deposits of the older 

 inundational areas are of alluvial origin, as also are those now being 

 formed ; therefore, in determining the limits between the pleistocene 

 and modern formations, the outlines of the former may prove to the 

 geologist a valuable guide. 



He also describes old, and now abandoned, river-beds ; the best 

 opportunity of examining which is afforded in the tract of land in 

 Hungary between the Theiss and the mountainous western boundary 

 of Transylvania. Similar ancient river-beds are to be found along 

 the Danube, and especially on the plains of Moldavia, where they 

 appear as valleys of erosion having connexion with that river ; and 

 they also occur along the Pruth and Sereth. All these channel-like 

 depressions are now dry, or if they are sometimes conveying water, 

 yet it is in a quantity quite inadequate to the dimensions of the 

 excavation, which are greater than those of the beds of the adja- 

 cent rivers ; and being as regards the direction identical with the 

 latter, they must be regarded as constituent parts of the present 

 river-system : and they may also be considered as relics of a period 

 subsequent to that in which the existing mountains and valleys were 

 formed, but when the water flowed at a higher level, that is, nearer 

 to the surface of the plains, and was also conveyed in a greater 

 number of channels than it is now. The beds of the present rivers 

 were developed from these in such a manner that, as the water sank 

 gradually in a deeper basin, its fall became greater, its current more 

 rapid, and therefore it was enabled to cut out deeper beds. It 

 selected, out of the many shallow channels, those few which offered 

 the least resistance to the excavating power. The ancient river- 

 beds on the left bank of the Theiss are as curvilinear as the modern 

 ones ; while those on the Moldo-Wallachian plains are as straight 

 as the present rivers of that district. This coincidence may be 

 regarded as indicating that the collateral circumstances are the same 

 now as they were during those periods when the ancient river-beds 

 were in full request. 



Dr. Szabo then refers to the chief points of interest in individual 

 localities, not only in the course of the Danube, but in its basin 

 further inland, where, on heights that are now quite unattainable 

 by floods, incontestable traces of alluvial deposits are found super- 

 imposed upon the Loess. The most remarkable of such places are 

 Zimony (Semlin) and Csernavoda. On the former, situated opposite 

 Belgrade, the loose deposits forming, the precipitous sides of the 

 Danube consist, for the most part, of diluvial strata ; in the lower 

 portion of which bones of Elephas, "Rhinoceros, Bos, &c, are met 

 with. The upper portion is the true Loess, and it is covered with 

 newer strata consisting partly of sand of about 15 ft. in thickness 

 and containing pleistocene fossils, partly of clayey materials, from 

 5-9 ft. thick, with fragments of earthenware, bones of Bos and 

 Cervus, charcoal, flint worked by man, and, in some places, fresh- 

 water shells such as Unio pictorum and U. Batavus. The whole for- 

 mation becomes thinner inland, and thicker towards the Danube, 

 where it also becomes abruptly cut off. 



