EVIDENCES(?) OF WATER-DEPOSITION OF LOESS. 375 



It is an interesting fact that most loess, especially where 

 there has evidently been rapid deposition, shows similar lami- 

 nation if broken vertically. Such lamination is shown in Plate 

 XIII, fig. 1, and also in Plate VII, fig. 1 of Professor Wright's 

 article, and is wholly unlike water-lamination, as may be de- 

 termined by comparing it with sections of pond-mnd which 

 has cracked and scaled off on drying. The writer has seen a 

 few exposures in which what appears to be water-lamination 

 (which is much more regular and much less like cross-bedding 

 on a minute scale than wind-lamination) may be observed, 

 but these bands appear only between different loesses, as if 

 the older loess had been over-washed for a short time, or at 

 intervals, by water from the melting glacier which had inter- 

 rupted the formation of the loess. Another possibility is well 

 illustrated by the C. G. W. Ry. cut east of Lanesboro, Iowa. 

 Here there is evidently a buried pond, into which loess- 

 materials had been carried by winds and erosion from higher 

 parts of the ridge, until this portion of the pond was com- 

 pletely filled. The loess material in this old pond is very dis- 

 tinctly stratified, and contains numerous bands of iron oxide.* 

 Its only fossils are shells of a Pisidium, a small bivalve which 

 now inhabits prairie pools and streamlets. The same ridge 

 still retains what appears to be a part of the same bog, and 

 such bogs and ponds are common in Iowa on both drift and 

 loess ridges. But these cases are rare and purely local, and 

 the lamination here observed is wholly unlike that which loess 

 usually reveals when broken vertically. They furnish no 

 warrant for the general conclusion that the whole deposit was 

 formed in great bodies of water, and it could be drawn from 

 this evidence only in utter disregard of the processes which 

 may be observed in the same region today. 



Professor Wright's additional evidence in support of the 

 theory of water-deposition of loess, contained in pp. 210-222 

 of his paper, is equally unsatisfactory. Stripped of its ver- 

 biage it may be briefly summed up in the statement that 1.) 



*See PL XIV, fig. 1. 



