number of samples from the Colville River and 

 the Harrison Bay. The sample preparation and 

 analytical procedures for these subfractions were 

 slightly different than for the <2/A fraction and, 

 therefore, are elaborated upon as follows. 



The bulk sample was wet-sieved with 

 deionized water, using a 230-mesh (62 /x) stain- 

 less steel sieve. The resultant <62/jl material was 

 treated with H2O2. using the method described by 

 Jackson ( 1956) in order to remove organic matter. 

 The pH was monitored during this treatment 

 (Douglas and Fiessinger, 1971). The most acidic 

 value observed was 6.6, suggesting little likeli- 

 hood of significant clay mineral modification re- 

 sulting from this treatment. 



The resultant sedimentary material was sus- 

 pended in 1000 ml graduated cylinders, in 

 deionized water, and all the <2/u, e.s.d. size 

 material was removed by repeated stirring, resus- 

 pending and differential settling of the coarser 

 material ( >2fJi e.s.d.). The suspended <2/A ma- 

 terial was removed by siphoning. 



Less than 2/i, material was subjected to further 

 particle-size fractionation, using centrifugal 

 sedimentation, following the methods described 

 by Jackson (19.56). The <0.3fx e.s.d. size frac- 

 tion was removed first, followed successively by 

 the 0.3 — <1.0/u, e.s.d. size fraction, and then 

 the 1.0 — <2.0/x e.s.d. size fraction. 



For the resultant materials from station CR-5 

 (Figure 2), each of the particle-size fractions ob- 

 tained was divided into two portions. One aliquot 

 w as reserved for analysis as described below, the 

 second aliquot was first subjected to the treatment 

 described by Jackson (1956), for the removal of 

 free-iron-oxide from sediment. 



For each particle-size fraction, for each sample 

 location, seven specimens were prepared by plac- 

 ing aqueous suspensions on porous ceramic 

 plates. By a vacuum applied to the underside of 

 each plate, the suspended clay material was 

 sedimented onto the surface of the plate in such a 

 manner that the basal planes of the layer silicate 

 minerals are predominantly aligned parallel to 

 the surface of the plate. 



Various further treatments were performed on 

 the various plate mounts of each particle-size 

 fraction of each sample, followed by X-ray dif- 

 fraction analysis. 



Specific Treatments and Clay Mineralogic 

 Analysis 



1. Saturation with ethylene glycol — This 

 permits the detection of the presence of materials 

 (e. g. , smectites and some vermiculites, as well as 

 mixed-layered phases containing either of these 

 as component layers) into which molecules of 

 glycol may associate themselves in interlayer 

 structural sites. The resultant interplanar basal 

 repeat distance for smectites is in the neighbor- 

 hood of I7A. 



2. Saturation with KCl (IN)— This affords 

 the opportunity for exchange of K"^ onto such 

 appropriate interlayer structural sites as may 

 exist in any of the mineral phases present. The 

 present consensus regarding this phenomenon 

 seems to be that materials variously described 

 (often somewhat nebulously) as "stripped, weath- 

 ered, degraded" illites or micas, "soil vermicu- 

 lites," etc. will readily accept K ions into inter- 

 layer structural sites formerly occupied by K 

 prior to the "degradation" process. This results in 

 the "collapse" of the degraded stiucture, and is 

 reflected in the X-ray diffraction analysis as a 

 shift in basal spacings from somewhere >10A to 

 approximately the lOA region. The term "illite" 

 might be used to collectively designate materials 

 of this sort, but other studies (e.g., Hower and 

 Mowatt, 1966) have indicated that there are other 

 aspects relative to this problem w hich are difficult 

 to distinguish in working with polyphase assemb- 

 lages such as the present study. In our present 

 study illite has been adopted as a term of a more 

 descriptive nature, for all "lOA material." 



This further leads to the necessity here for a 

 brief discussion of our handling of the matter of 

 "interstratified," or "mixed-layer" materials. In 

 view of the problems regarding the unraveling of 

 diffraction effects from polycomponent assem- 

 blages, it seems best to merely generalize in a 

 descriptive manner with respect to mixed-layer 

 materials in our samples. The matter of mixed- 

 layering has been dealt with recently by Hower 

 (1967), Reynolds (1967), and Reynolds and 

 Hower (1970) treating the problem of varying 

 degrees of ordering within these materials, for 

 simplified cases. The natural assemblages are 

 undoubtedly more complex, and thus even less 



241 



