PLEISTOCENE SUBMERGENCE IN COLUMBIA VALLEY 493 



kind in the materials exposed in the 500-foot sections they studied. 

 Absence of anything attributable to floating ice, presence of a 

 fauna of land vertebrates, and the existence of a broad valley cut 

 in the Ringgold formation containing gravel deposited probably 

 during subsiding stages of the submergence seem adequate evidence 

 for ruling the Ringgold formation out of the catalogue of records of 

 Lake Lewis. 



"Sediments north of Saddle Mountains." — It is difficult to deter- 

 mine just what Symons meant by this phrase. There are sediments 

 in that region which are warped with the basalt, and there are hori- 

 zontal sediments, noted as lake beds of Pleistocene age,^ which lie 

 below the upper limits of this submergence. These are very poorly 

 exposed and best known from well records. There are also fluvio- 

 glacial gravels, deposited by the diverted Columbia during sub- 

 siding stages of the submergence and correlative with the gravel 

 terraces of the present Columbia Valley. 



"Rounded bowlders and a loose, light, powdery soil.^^ — These occur 

 south of Badger Mountain and Crab Creek, surrounding Saddle 

 Mountain, and in the lower portions of the valleys of Yakima River, 

 Walla Walla River, Snake River, and Moses Lake. Symons here 

 grouped a congeries of deposits of varied genesis: fluvial, fluvio- 

 glacial, static water, and wind. 



Gravel terraces (cited by Symons) . — These are fluvial and fluvio- 

 glacial deposits and probably only the Great Terrace, above noted, 

 can be correlated with Lake Lewis. 



Neither Condon's nor Symons' work was more than hasty 

 reconnaissance. No one then knew that the sediments of many 

 successive Tertiary basins are exposed in the region, and neither 

 observer was carefully discriminative. Neither one noted the 

 existence of erratics in the Columbia Valley. Correlation with the 

 Champlain epoch of the eastern states was with both wholly a 

 matter of inference, on the assumption that the Pacific Coast must 

 have been submerged if the Atlantic Coast was. 



Russell (1893) was the first to recognize the significance of the 

 erratic bowlders as evidence for the existence and the age of the 



' A. T. Schwennesen and O. E. Meinzer, " Ground Water in Quincy Valley, Wash- 

 ington," U.S. Geol. Surv., Water Supply Paper 425-E, 1918. 



