The origin of textural lamellae in Quaternary coast sands of Natal

Abstract

A new concept of the formation of textural subsoil lamellae has been developed on the basis of their morphology in aeolian coastal deposits in Natal. It has been concluded that they are initiated somewhere at depth in the profile by a single, partial impediment to the downward movement of clay-size materials. The impediment may or may not be readily observable. Because clay is accumulated at the upper surface of a lamella and lost at the lower surface, the lamella will migrate upwards through the profile although the net movement of day ts downward. After a lamella has departed from the initiating plane, a new lamella will start forming at this level and the process will be repeated. Movement of a lamella upwards will eventually lead to its disappearance at shallow depth in the profile by wasting as the diminishing supply of clay no longer balances the loss Micromorphological data have indicated that large amounts of clay in lamellae occur in a non-oriented fashion. The largest porpor of this clay is illuvial, whereas some may have formed neogenetically