Evidences(?) of water-deposition of loess. 373 



jections to the writer's conception of the source of material, 

 presented in Miss Owen's paper. She asks: "..... where could 

 there have been river bars of sufficient extent to yield the 

 supply for the deep mantle covering the region about St. 

 Joseph?" Miss Owen might look out, at St. Joseph, across 

 the Missouri to the west, and she can see some of them.* 



Here there are extensive bars and sand-dune areas, and the 

 writer has seen great volumes of dust and sand raised from 

 these bars, the sand being soon dropped, while the dust 

 was widely diffused. Such bars are common at low r water 

 not only in the Missouri, but in all streams with wide valleys, 

 and each succeeding flood brings new fine material to be again 

 transported to the uplands. Loess is evidently a deposit which 

 required a long period for its formation, and consequently 

 accumulated only a little at a time. 



It is surprising, however, that a resident of the Missouri 

 valley familiar with these bars, and with the dust-storms which 

 are so common, should resurrect this question. 



Miss Owen further says: "Then too, it might be asked, by 

 what law of nature did the winds confine their energy wholly 

 to the fiat, low-lying river bars while the higher and, sup- 

 posedly, dryer mantle of till and beds of residual clay remained 

 undisturbed to be gently but deeply covered?" In reply it may 

 be said that it is the same law as that which today prevents 

 winds from raising quantities of dust from plant-covered slopes 

 and hills, while great clouds of it are carried upward from 

 barren sandbars. During dry seasons, or in barren places, 

 even the highlands yield dust, but so long as vegetation holds 

 its own not only is there no wind-erosion, but the covering of 

 plants retains much of the dust brought to it from other 

 sources. 



But Professor Wright's chief objection to the writer's ex- 

 planation of these phenomena is contained in the statement 

 that the explanation "notably fails to account for numerous 



*See PI. XIII, fig. 2. 



