176 HR. C. T. TRECHMANN ON INTER GLACIAL [vol. lxxv, 



composition with at least one typical sample of Continental loess, 

 it differs in the absence of the land shells and the tubular 

 calcareous vegetable structures that often characterize the loess of 

 Europe. However, the sample preserved on the Durham coast 

 is so small and limited in extent that this difference may not 

 be of serious import, besides which the prolonged weathering and 

 decalcification that it has undergone may have dissolved out any 

 land shells or calcareous tubules (if such were originally present 

 in it). 



The surface of the Magnesian Limestone immediately underlying 

 it is often rubbly, and is fissured and cracked in places. The 

 surface is covered, and the cracks are filled with rubbly limestone, 

 small Scandinavian stones, cracked flints, and rounded sand-grains, 

 and the whole mass to a depth of 10 feet or more in the cracks is 

 strongly calcreted, the cementing material having probably been 

 derived from the overlying loess. 



The upper part of the section, which consists of loess disturbed 

 and redeposited by water, is devoid of the calcareous concretions. 



A layer of this material about 2 feet thick covers the Magnesian 

 Limestone at the top of the cliff for some distance south of the 

 old Preglacial valley, and in this was found the big boulder of 

 titaniferous syenite (presently to be described) which showed so 

 much surface-decomposition. 



In the old Preglacial valley south of the fissure, exposed on the 

 foreshore and in the fissure itself, the Scandinavian Drift in its 

 upper part is considerably commingled with yellow redeposited 

 loess containing streaks of sand and pebbles, Scandinavian stones, 

 and bits of flint and chalk and marine shells. This seems to show 

 that the Scandinavian ice-sheet advanced somewhat slowly and 

 intermittently: also that loess was deposited round its edge during 

 its advance, and was overridden and incorporated with the Drift. 

 The main mass of the loess, however, was banked up against the 

 southern slope of the old valley, and upon the stony and shelly cla}-, 

 after the Scandinavian ice-sheet had begun to retreat. 



I have not found any definite trace of loess in connexion with 

 the red fissures containing freshwater clay and vegetable matter 

 presently to be described. 



III. Chemical and Mineralogical Composition of 

 the Loess. 



The material is extremely fine, and when dry can generally be 

 crushed between the fingers, when it falls to a very fine dusty 

 powder. Samples riddled through a sieve of 240 meshes to the 

 linear inch left a residue on the sieve of, in one case, 3*26 percent., 

 and in another case of only 1*29 per cent. 



A sample of Less from Kreuzberg, near Bonn, belonging to the 

 (leological Collection of the Armstrong College (Newcastle-upon- 

 Tyne), was similarly riddled, and left a residue of 3*95 per cent. ; 

 consequently, the residue of the Durham loess amounts to less than 

 that of the Continental sample. 



