Evans did not, however, follow Lubbock's general trend, which was typological classification. He chose instead to use type of find site as the main criterion, following Lubbock's descriptive terms, such as tools of the drift. Lubbock had identified drift sites as containing Palaeolithic material. Evans added to them the cave sites. Opposed to drift and cave were the surface sites, where chipped and ground tools often occurred in unlayered contexts. Evans decided he had no choice but to assign them all to the most recent. He therefore consigned them to the Neolithic and used the term "Surface Period" for it.