"The dating of the Palaeolithic in the Plakias region presents a considerable challenge, not least because of the long period of time that may have elapsed since the occupation of the earliest sites, during which postdepositional natural processes may have obscured the archaeological record. Additionally complicating the issue are the small number of sites, the lack of excavation, and the impact of modern development on the area, which has destroyed many sites.
Several approaches to dating were attempted, and our research on this topic continues. At Preveli 2, east of the Preveli Gorge, Palaeolithic artifacts are associated with a flight of marine terraces resulting from relatively high sea levels in the Pleistocene that were preserved by subsequent rock uplift. The lowest late Pleistocene marine terraces resulting from high stands of the sea at Preveli (14 ± 1 masl) and Schinaria (21 ± 1 masl) have 2-sigma calibrated radiocarbon ages of 45,400 ± 1,600 and 49,120 ± 2,890 years b.p., respectively, and are correlated with Marine Isotope Stages 3.3 and 3.4, both eustatic high stands. The higher terraces, at 59 and 96 masl, are unquestionably older. How much older? Assuming similar rates of rock uplift (1.4 ± 0.1 m/kyr) determined from the age-elevation relationships of the dated terraces at 14 and 21 masl, it is possible to estimate the approximate ages of the terraces associated with artifacts. This correlation provides an approximate age for the lithic artifacts. The higher terrace, at 96 masl, may belong to Marine Isotope Stage 5, possibly early 5e, ca. 110,000 b.p. Artifacts associated with the terrace at 59 masl could correlate with Marine Isotope Stage 5a, ca. 70,000 b.p. It should be stressed that these are rough approximations and these ages are probably minima that represent a terminus ante quem. If the uplift rate is changed, the terraces and the artifacts associated with them could be much older.
At Preveli 3, Preveli 7, Timeos Stavros 1, and Schinaria 5, Palaeolithic artifacts were found in outcrops of paleosols that exhibit the characteristics of the oldest maturity stage for such features, that is, Maturity Stage 6, or in geological terms, Marine Isotope Stage 6. Together these observations suggest an age of ca. 190,000–130,000 b.p. and serve as a terminus ante quem for the artifacts embedded within them. The stone tools were incorporated in the paleosols as part of a process described by Runnels and van Andel in Epirus: “the top of the Bt horizon itself would move gradually upward as a result of slow deposition, so engulfing any artifacts laid down on former land surfaces above it.” In other words, the Bt horizon, especially as much of the clay comes from eolian sources, will increase in thickness through time, slowly
engulfing clasts, such as stone tools, that were formerly in the A horizon.
In sum, the dating of the Palaeolithic sites is based on geological data derived from the study of marine terraces on the southwestern coast of Crete and our identification of paleosols, and these data place the Palaeolithic lithic artifacts firmly in the Pleistocene, ca. 130,000 b.p. or earlier. The chronology can be further refined, however, and a dating program
currently in progress may provide data for doing so." (references excised)
So, bottom line, the dating is largely indirect, but grounded by dated references points that provide a minimum age for the terraces where the handaxes were recovered. Interestingly, this indicates that these tools are, at most, 130,000 years old. Given that there do not appear to be more recent Paleolithic age (the rest of the implements reported in the paper are Mesolithic in age and techno-typology, which is an important discovery in and of itself), this implies that on current evidence, Crete was not occupied during the Late Pleistocene (ca. 130,000-10,000 BP). Why this was the case (and how an early colonization took place) is an interesting question that will need to be answered by future research.
In the meantime, here are a few take-away observations from the Strasser et al. (2010) report. First, on the basis of the drawing of the handaxes, these implements do appear to be human-made. Second, they are not isolated occurrences: the authors identified nine localities where these quartz tools were found, only three of which also yielded Mesolithic tools. This leaves open the possibility that the 'Paleolithic' sites represent task-specific components of the Mesolithic toolkit on Crete, but this is unlikely based on the association of handaxes with some of the terrace deposits described in the quote above. Third, as the authors indicate, this was not a case of a H. heidelbergensis (or a couple of them) washing onto Crete: the fact that nine sites (defined by the presence of a minimum of 20 stone tools) were found in a relatively small area indicates a somewhat sustained human presence on the southern coast of Crete. This does suggest that people got there purposefully (i.e., using some kind of watercraft), which leaves open the question of why Middle and Upper Paleolithic assemblages haven't (yet?) been found in the region or elsewhere on Crete (or any other large Mediterranean island, for that matter).
As a parting observation: one aspect of the discovery that definitely wasn't stressed in the media reports about these finds is how they were made. They were breathlessly reported as 'discovered' without much context. The authors actually set out to look for Mesolithic sites in southern Crete using a model developed for the Greek mainland that identified certain areas as having been most appealing for Mesolithic foragers. In other words, this wasn't a blind search for early stuff or simply a fortuitous discovery. Rather, it came about as the result of an explicit research design targeting some very specific questions. Good to see more of that in Paleolithic archaeology.
Strasser, T., Panagopoulou, E., Runnels, C., Murray, P., Thompson, N., Karkanas, P., McCoy, F., & Wegmann, K. (2010). Stone Age Seafaring in the Mediterranean: Evidence from the Plakias Region for Lower Palaeolithic and Mesolithic Habitation of Crete Hesperia, 79 (2), 145-190 DOI: 10.2972/hesp.79.2.145