730 ROLL.IN D, SALISBURY 



OTHER OBSERVATIONS 



In addition to the foregoing work, some further data were 

 gathered at several points, touching Pleistocene geology in the 

 West. It was found that loess has somewhat extensive devel- 

 opment in eastern Washington and northeastern Oregon, though 

 its limits were not determined. It is widespread in Douglas, 

 Lincoln, Whitman, Columbia, Walla Walla and probably Spo- 

 kane counties, Washington. It is very generally ^distributed 

 over the northern part of Umatilla county, Oregon. In geo- 

 graphic distribution it seems to correspond, in a general way. 

 with the great wheat belt of the states mentioned. In topo- 

 graphic distribution, it has the general habit of the corre- 

 sponding formation in the Mississippi basin ; that is, it has a 

 preference for considerable elevations. So far as seen, how- 

 ever, its disposition to follow streams is less pronounced than 

 in the Mississippi basin east of the Missouri. Its variations 

 in composition and structure, too, are similar to those of the 

 loess of the interior. Its thickness is very variable, and for 

 the most part undetermined, but locally it is at least twenty- 

 five to thirty feet thick, and its maximum is probably consider- 

 ably more. In many places, as at BoUes Junction (Walla Walla 

 county), it abounds in calcareous concretions of the usual loess 

 type. In other places, as at Alto (Columbia county), it assumes 

 the columnar structure, so characteristic of the loess of some 

 other localities where the formation is well known. In many 

 places, it constitutes the entire mantle rock. In some places it 

 is associated with sand, which may be either beneath it or inter- 

 bedded with it; and in other localities it contains considerable 

 beds of volcanic ash. The sand and volcanic ash associated 

 with it are sometimes distinctly stratified. In some cases, the 

 stratification is clearly the work of wind, but in others this was 

 not evident. The impression gained was that much of the loess 

 seen is of eolian origin. 



Observations on glaciation were made at several points, aside 

 from tliDse enumerated in the preceding pages. Data sufficient 

 for the intelligent direction of future Pleistocene work were 



