Adjustment of clays to chemical change and the concept of the equivalence l vel

Further x-ray and chemical work on suspended sediment samples and cored samples from the James River and its estuary support earlier proposals by the author. A chlorite-like clay is forming from weathered illite through a mixed-layer illite-vermiculite-chlorite stage, and some illite is seemingly regenerated to a be~ter itli~e by potassium fixation. Chemical analyses of interstitial water, hydrochloric acid-leachate, and fused samples offer explanations regarding the chemical changes occurring in clays as composition of the environment changes. Magnesium is adsorbed by clays to a far greater degree than potassium in the marine and brackish environment. The variance between clays found in Recent and ancient sediments i related to and explained by the concept of the equivalence l vel. I t is suggested that K+ is adsorbed preferentially to Mg 2+ by clays when they have been buried to a depth that is greater than that of the Mg 2+- K +-- equivalence l vel; above this level lV[g~+ is preferentially adsorbed by the clays. The trifold nature of clay minerals in terms of their origin and distribution is briefly discussed