[AI] For papers by Berendt and his associates see especially the _Jahrbuch d. k. preuss. geol. Landesanstalt_, and the _Zaitschr. d. deutsch. geol. Ges._ for the past few years. Geinitz: _Forsch. z. d. Lands- u. Volkskunde_, i. 5; _Leopoldina_, xxii., p. 37; I. _Beitrag z. Geologie Mecklenburgs_, 1880, pp. 46, 56. Sederholm: _Fennia_, I. No. 7. The upper boulder-clay of those regions is now recognised as the ground-moraine of this latest ice-sheet. In many places it is separated from the older boulder-clay by interglacial deposits--some of which are marine, while others are of freshwater and terrestrial origin. During interglacial times the sea that overflowed a considerable portion of north Germany was evidently continuous with the North Sea, as is shown not only by the geographical distribution of the interglacial marine deposits, but by their North Sea fauna. German geologists generally group all the interglacial deposits together, as if they belonged to one and the same interglacial epoch. This perhaps we must look upon as only a provisional arrangement. Certain it is that the freshwater and terrestrial beds which frequently occur on the same or a lower level, and at no great distance from the marine deposits, cannot in all cases be contemporaneous with the latter. Possibly, however, such discordances may be accounted for by oscillations in the level of the interglacial sea--land and water having alternately prevailed over the same area. Two boulder-clays, as we have seen, have been recognised over a wide region in the north of Germany. In some places, however, three or more such boulder-clays have been observed overlying one another throughout considerable areas, and these clays are described as being distinctly separate and distinguishable the one from the other.[AJ] Whether they, with their intercalated aqueous deposits, indicate great oscillations of one and the same ice-sheet--now advancing, now retreating--or whether the stony clays may not be the ground-moraines of so many different ice-sheets, separated the one from the other by true interglacial conditions, future investigations must be left to decide. [AJ] H. Schröder: _Jahrb. d. k. preuss. geol. Landesanstalt für 1887_ , p. 360. The general conclusions arrived at by those who are at present investigating the glacial accumulations of northern Europe may be summarised as follows:--