## 4 Discussion and Conclusions  
The doses absorbed by the cobbles were directly derived by the aliquots taken from the first layer. Although the uncertainty in the dose is derived from the standard error of 10 aliquots, the relative error spans between 15% and 30%, it is quite high, especially if compared with that obtained with sediments (5-6%). Due the scarcity of material for each considered layer, it has been impossible to extract quartz or feldspar grains from the samples. This may have led to luminescence signals with inadequate characteristics (slow decay rate, high background) that introduced a high error in the fitting to calculate the absorbed dose. For US178, Pat12 and Pat15, the age from cobble is in agreement with the sediment age at a level of 1 standard deviation, thus, they are consistent with each other. From a methodological point of view, these preliminary results show that it is possible to apply luminescence dating to the surfaces of the artefacts present in the Ossimo-Pat site. Despite the high error obtained on rock surfaces, the data obtained on sediments under the rock were more precise. This suggests that for future application of surface dating of megalithic structure, it is recommended to sample both rocks and the underlying sediments in order to reduce the age errors. Moreover, the results of the dating offer, from an archaeological point of view, an interesting feedback to the existing timeframe of the site. Even considering the range error of each date, we can compare the results with what was already established about the site, chronology-wise. The first sample (the rock \"1/2016,\" 2760 BCE \(\pm\) 500) was taken from the northernmost of the votive stone circles. Its date is compatible with the other two samples from the nearby, similar, stone structures (samples \"US 178,\" rock, 2675 BCE \(\pm\) 500, and sediments, 3200 BCE \(\pm\) 330). There are no 14C dates available from these circles that have been dated to the first half of the 3 rd millennium BCE based on the objects found inside the circles, namely a specific type of arrowheads, usually related this period. The three OSL dates from the area would seem to confirm the current chronological framework. The IRSL date from the rock sample \"3/2016\" (1920 BCE \(\pm\) 250) seems equally aligned with the current chronology of the site. This rock was collected from the accumulation layer located behind the big monolith called \"Pat 2,\" one of the few still vertically standing. The small accumulation of soil and rocks is probably related to the first stage of abandonment of the site, right after its partial destruction and dismissal, and is usually dated around the 23 rd-20 th centuries BCE thanks to a charred coal 14C dating [1]. The samples taken from the monolith pits are the most intriguing ones, as we still do not have a full comprehension of the precise life cycles of these monuments. The samples taken from the housing pit of the monolith \"Pat15\" are related to its filling, which happened in time, after the dismissal of the site and the overthrowing of the monolith, which was pushed to the ground, out of its proper housing. The dating of rock and relative sediment (2470 BCE \(\pm\) 500 and 2265 BCE \(\pm\) 115, respectively) are perfectly coherent with the said action, which probably happened, as said, between the end of the 24 th and the 21 st centuries BCE. The dating of the samples from the housing pit \"Pat12\" (Rock: 5240 BCE \(\pm\) 600; sediment: 5090 BCE \(\pm\) 360), on the other hand, offer a very interesting result, related back to the end of the sixth millennium BC, before the foundation of the sanctuary. Nevertheless, these dates are perfectly coherent with another dating, obtained by 14C on a charcoal sample from the layer 181 [1], which was documented in this very sector of the site thanks to a deep stratigraphic trench.