264 University of California Publications in Geology [Vol. 10 



not been traced. As the Ringold deposits rise about 500 feet above 

 the Columbia at the southern end of the White Bluffs, and the river 

 has excavated a valley several miles wide south of this point, it is prob- 

 able that the beds originally extended a considerable distance down 

 the river, perhaps beyond Pasco. To the west the beds appear to 

 be bounded by the base of the basaltic Yakima Range, which lies at 

 distances from the river ranging up to fifteen miles or more. Con- 

 sidering the height to which the Ringold rises above the river in the 

 White Bluffs region, it is probable that this formation originally 

 extended up through the gap which the Columbia has cut across the 

 Saddle Mountains, and that it was deposited over areas north of that 

 range. 



More precise data concerning the areal distribution of the Ringold 

 and regarding its physiographic relations will be necessary before it 

 will be possible to offer a satisfactory statement of the factors which 

 caused the Columbia to deposit these sediments. From general con- 

 siderations it is probable that the accumulation was due: (a) to an 

 uplift across the course of the Columbia at some point downstream, or 

 (6) to a subsidence of the region which the Ringold now occupies, or 

 (c) to a change in the relation of the detrital load of the Columbia to 

 its transporting power. The last condition might be associated with 

 climatic fluctuations of the Glacial period or with marked changes in 

 position of the course of the Columbia which are known to have 

 occurred in the hundred miles or more of its channel north of the 

 Saddle Mountains. Additional field-work, which the writers hope 

 to carry out during a coming season, will be required before this 

 problem can be solved. 



Relation to the Ellensburg Formation. — In view of the difference 

 in age between the Ellensburg and Ringold faunas it is important 

 to know the stratigraphic relations of the formations in which they 

 occur. It is probable that the two sets of beds come in contact on 

 the western border of the Ringold, and perhaps at other points, but 

 none of these localities have been examined. If the very even surface 

 extending eastward from the White Bluffs be correctly interpreted as 

 a remnant of the original surface of deposition, the Ringold strata 

 probably lie approximately flat along the flanks of ridges consisting 

 in part of folded Ellensburg strata. Such field data as have been 

 obtained, taken with the palaeontologic evidence indicating difference 

 in age, suggest unconformity between the two formations. 



Transmitted March 7, 1917. 



