1917] Merriam-Buwalda: White Bluffs of the Columbia 261 



consists, as noted by earlier writers, chiefly of light-colored muddy 

 sandstones and sandy clays, and in minor part of fine gravels, volcanic 

 ash and calcareous strata. 



The following is an estimated section of the Ringold formation 

 in the "White Bluffs three to four miles below Hanf ord : 



Feet 



7. Loose yellowish clayey sand (summit of section) 85 



6. Gray limestone, often brecciated, irregular in thickness, forming a resist- 

 ant layer 3 



5. Cream-colored clayey sandstone, lacking resistance to weathering 75 



4. Brownish-yellow clayey sandstone, distinctly but thickly bedded, more re- 

 sistant, standing out as bluffs 75 



3. Yellow sandy clay, unindurated, poorly stratified 25 



2. Cream-colored clay, thinly bedded, including occasional thin layers of 



sandy material, giving quite prominent outcrops 25 



1. Nearly white clayey sandstone, in places pure sand, witli occasional thin 

 gravel layers of polished quartz pebbles. Fossils occurring near top 

 of this member, which extends from the Columbia River up to an ele- 

 vation of about 175 feet above the river 175 



Approximate thickness of section exposed above Columbia River .... 503 



Viewed from a distance individual beds may appear quite per- 

 sistent in the face of the bluffs, but the bulk of the material is not 

 thoroughly classified as to size, and therefore not sharply stratified. 

 The coarser materials are waterworn. Occasionally beds of coarse 

 angular materials, chiefly basaltic in character, are found at the top 

 of the bluffs, but these are evidently later deposits laid down in chan- 

 nels cut in the Ringold by water courses heading in the country to the 

 east and north. The strata of the Ringold lack induration and are 

 notably softer than most exposures of the Ellensburg. "While they 

 exhibit steep slopes, especially where the Columbia has recently cut 

 into the base of the bluffs, exposures tend to assume rounded outlines 

 and a subdued topography, even under the prevalent conditions of 

 semi-aridity. 



Physiography and Structure. — Direct observations on the struc- 

 ture of the Ringold were limited to the "White Bluffs exposures, but 

 certain inferences as to the attitude of these beds in other parts of 

 the area seem possible from physiographic considerations. So far as 

 could be judged, the strata in the "White Bluffs lie parallel to the 

 water surface of the Columbia River. All recognized cases of appar- 

 ent deformation seem to be due to landslide. 



The WTiite Bluffs follow the river closely from a point ten or 

 twelve miles north of Pasco to the northwestward for about thirty 



