70 T. F. Jamieson — Climate of the Loess Period. 



it places beyond all doubt what has been until recently l an undecided 

 point, the extension of the Basement Clay over Flamborough Head, 

 and consequently over a large area in the region to the northward, 

 and this will materially affect the classification of the drifts of that 

 part of the coast. 



In conclusion, it may perhaps be as well to mention that the place 

 where the shell-bed is to be seen is on a steep slope at the top of 

 a chalk cliff, and, though not really dangerous, is certainly not 

 easy of access, and is formidable-looking to any one unaccustomed 

 to clamber about on high places. 



V. — On the Climate of the Loess Period in Central Europe 

 and the Cause which Produced it. 



By T. F. Jamieson, Ellon, Aberdeenshire. 



TTNDEE the name of " Loess " there has been confounded two 

 U kinds of deposit which are due to entirely distinct and 

 different causes. One is the fine-grained sediment left by the 

 muddy water of flooded rivers and streams of all sorts ; the other 

 is the powdery dust and sand carried by wind, which in dry regions 

 often produces large accumulations of this nature. 



It would be well, I think, if the term " Loess " were restricted 

 to this latter deposit, or at all events it would be desirable to have 

 a distinct geological term for each kind. There is no doubt, how- 

 ever, that both agencies have frequently contributed to the formation 

 of these so-called Loess-beds, for in one and the same locality blown 

 dust and watery sediment may be lodged alternately, according to 

 the varying phases of the weather. 



Many years ago Morlot in Switzerland, and Collomb in Prance, 

 pointed out that much of the material to which the term " Loess " is 

 applied in these countries had probably been derived from the 

 muddy streams which flowed from the old glaciers of the Ice-time, 

 for water issuing from the bottom of glaciers is generally loaded 

 with a fine floury sediment produced by the grinding action of the 

 ice upon the mineral matter beneath it. This explanation accord- 

 ingly met with very general approval ; but when the German geologist 

 Eichthofen extended his travels into Northern China and Mongolia, 

 he there found Loess-beds developed on a gigantic scale, and dis- 

 played in such a way as to announce in no obscure language the 

 cause which produced them. In these arid regions the desert winds 

 play an important part in the economy of nature, and carry along 

 great clouds of sand and dust which they drop in more sheltered 

 places where their force begins to slacken. In moist climates 

 the fine earthy powder which is continually forming on the surface 

 of the country by the action of the weather is washed off by the 

 rain and rivers ; but in rainless districts it is left to the mercy of the 

 winds, which in the course of long ages gather deep beds of it, 

 and these so closely resemble in character and in organic contents 



1 See Eeport on, Buried Cliff at Sewerby, British Association for 1888 (p. 335). 



