structural:expansion
The Epipaleolithic and Protoneolithic of Stjerna and Obermaier

Sir John Evans never changed his mind, giving rise to a dichotomous view of the Mesolithic and a multiplication of confusing terms. On the continent, all seemed settled: there was a distinct Mesolithic with its own tools and both tools and customs were transitional to the Neolithic. Then in 1910, the Swedish archaeologist, Knut Stjerna, addressed another problem of the Three-Age System: although a culture was predominantly classified as one period, it might contain material that was the same as or like that of another. His example was the Gallery grave Period of Scandinavia. It was not uniformly Neolithic, but contained some objects of bronze and more importantly to him three different subcultures.