[Various (1971)] This process of material substitution probably involved significant technological and motor habit changes, since both the stone represented-quartz, quartzite and flint-and the form of its occurrence, in shore or bank pebbles or in quarried strata, differed considerably. A careful study of the debitage of the quartz pebble and flint strata industries might yield some interesting data on this question. In this connection it is important to add that, although a marked preference for a particular raw material can readily be observed in most of our prehistoric cultures, it is also clearly evident that groups moving into new locales in which the preferred traditional stone material was no longer readily available, discovered and utilized new substitutes.