10 E. R. Rou-orfh—A Great Post-Gkcial Flood, 



the Loess are inconsistent with the facts, and to formulate another 

 theory which it is hoped may prove to be more consonant with 

 them. The only demand I make in limine is that the position shall 

 be examined impartially and untrammelled by a priori theories, which 

 are more agreeable to theological than to scientific modes of reason- 

 ing. Theories which, however supported by great names, are mere 

 tentative hypotheses, excellent as working hypotheses so long as they 

 explain the facts, but to be discarded directly our induction shows 

 them to fail in so explaining them. 



It will be convenient to begin our examination with the Loess 

 or Lehm of German writers. Sir Charles Lyell, in speaking of the 

 Loess, says, " Some skilful geologists, peculiarly well acquainted 

 with the physical geography of Europe, have styled the Loess the 

 most difficult geological problem, although belonging to the period 

 of existing land-shells and the highest and newest by position of all 

 the great formations" (Antiquity of Man, p. 372). 



Much has been written upon the Loess since Sir Charles 

 Lyell penned these weighty words ; but it may be fairly said that 

 the difficulties in regard to it seem greater and more insoluble 

 now than at anj"^ previous epoch of geological inquiry. It has been 

 the fashion to correlate the Loess with the loamy deposits of France 

 and South Eussia and the brick-earths of Britain, etc. This view 

 we believe to be erroneous. Neither in structure nor in origin is the 

 Loess to be compared with the diluvium of the French writers nor 

 with our brick-earths. And in this paper we shall limit the term 

 strictly to the Loess proper, or Lehm, which is otherwise called, 

 according to Von Leonhard, in various parts of the Ehine Valley, 

 Loesch, Schneckenhausel-Boden, Mergel and Briz (Hibbert-Ware, 

 Volcanoes of Neuwied, p. 185). 



The first important fact we have to face is that the Loess of Central 

 Europe and of China is precisely the same in composition, distribu- 

 tion, and contents. The European Loess has been graphically de- 

 scribed by Mr. Geikie, and I cannot improve on his description. 

 He speaks of it as " a yellow or pale greyish-brown, fine-grained, 

 and more or less homogeneous, consistent, non-plastic loam, consisting 

 of an intimate admixture of clay and carbonate of lime. It is 

 frequently minutely perforated by long vertical root-like tubes, 

 which are lined with carbonate of lime, a structure which imparts 

 to the Loess a strong tendency to cleave or divide in vertical planes. 

 Thus it usually presents upright bluffs or cliffs upon the margins of 

 streams and rivers which intersect it. Very often it contains con- 

 cretions or nodules of irregular form, which are known in the Ehine 

 district as Loessraannchen or Loesspiippchen and in that of Danube 

 as Loesskindeln" (Prehistoric Europe, p. 144). With this account of 

 the Loess of Germany may be compared that given by Eichthofen 

 of the Chinese Loess. He says, " The Loess is among the various 

 substances which would commonly be called loam, because it is 

 earthy and has a bi'ownish-yellow colour. It can be rubbed between 

 the fingers to an impalpable powder, which disappears in the pores 

 of the skin, some grains of very fine sand only remaining. By 



