Gibraltar (36°7′N, 5°20′W) is located at the southern end of the Iberian Peninsula (Figure 1A). The western coast is sheltered by a wide bay, while the eastern side faces the Mediterranean Sea and is subjected to intense wave action. This particular phenomenon led to the creation and development of cavities of which Gorham's Cave is one7. Its sedimentary filling, from the deepest galleries to the present sea level, comprises a pure sandy aeolian record accumulated as a cliff-dune during climatic transgressive episodes. In the outermost area are frequent rock falls consisting of thin clast layers and seismic-like rock avalanches. In the inner sector the stratigraphy only displays local rock fall, aeolian dust and karstic clay8.

Figure 1 (A) Location of Gorham's Cave, Gibraltar, in the southern Iberian Peninsula; (B) Top: General plan of Gorham's Cave showing the location of the excavated sectors [outer sector including the entrance and middle area of the cave and inner sector (back of the cave)]; Bottom: Geological interpretative section of Gorham's Cave (NW-SE section or B-A projection in top) based on Jiménez-Espejo et al.7 and previous publications (e.g.9,10,12,16); (C) Geological sequence of Gorham's Cave - left: schematic profile of the outer sector (middle area of the cave) modified from Collcut15 (see Barton et al.27 for more details); right: stratigraphic profile of the inner sector. Red boxes mark the archaeological levels/units studied here. The photograph in (A) was taken by C. Finlayson and the maps/graphs in (A, B) were made by J.R. and J.R.-V. by using CorelDRAW Graphics Suite 12 and CorelDRAW X3 software. We would like to acknowledge S.N. Collcut and R.N.E. Barton for the permission granted for the use of the geological sequence of Gorham's Cave shown in C-left, courtesy of the School of Archaeology, Oxford. Full size image

The first excavation was carried out at the outermost zone of the cave (entrance area) by Waechter9,10 and was characterised by a low density of archaeological remains. The sediments were composed of interbedded and irregular-layered bright red clayey sand, reddish brown clay/sand with abundant charcoal flecks, dark yellowish brown compact clay/sand and tank/pink sands and clays11,12. Abundant limpets, other shells and coarse, angular travertine roof falls occur within the lighter pink calcareous sandy units. The outer area was also excavated in its middle sector by Waechter9,10 and later by Barton et al.13 and Stringer et al.14 (Figure 1B) and displays a lower sedimentation rate but also high human activity. These sediments tend to be somewhat less sandy than those in the outermost zone but are similar overall. In general, they include dark-brown organic-rich silty clay, grey sand and irregularly bedded yellowish-brown sand containing coarse charcoal fragments; brown-black organic-rich clay with whitish gritty phosphatic lenses; and interbedded, massive, homogeneous, coarse brown sand (see Collcut15 for more detail). The inner sector was excavated at the beginning of this century by the Gibraltar Museum and the first results were published by Finlayson et al.16. The excavations exposed an area of about 29 m2 of cave floor and produced a stratigraphy with 4 main occupation levels (I–IV from top to bottom). The sedimentary record in this zone is thinner than in the outer part of the cave due to the higher position of the bedrock. Likewise, its sedimentary composition differs from other sectors due to a predominance of clay minerals, calcite and quartz, with small quantities of dolomite, ankerite and feldspars7. The inner sedimentary series seems to register a more condensed record than the outer zone, making the stratigraphic and chronological correlation between excavation areas difficult.

In the inner area, the chronology is based on a stratigraphically coherent series of AMS (Accelerator mass spectrometry) radiocarbon dates obtained from charcoal fragments. Level III is dated between ca. 12,640 and 10,880 BP for the Magdalenian horizon (level IIIa) and between ca. 18,440 and 16,420 BP for the Solutrean horizon (level IIIb). Level IV is dated between ca. 32,560 and 23,780 BP15. In the outer area, a combination of AMS radiocarbon and OSL dates is used to locate chronologically the outer deposits. Radiocarbon results reported by Higham et al.17 indicate an age of between ca. 29 and 51 kyr BP for UBSm.7 and BeSm.1. Nevertheless, the dates from the underlying LBSmff.1–5 of between ca. 42 and 56 Kyr BP suggest that most of the charcoal fragments from UBSm.7 and BeSm(OSsm) could have been moved up by the soft sediment loading17. The Single Grain (SG) OSL chronology and the Bayesian age model show sediments of MIS 5 age near the base of the sequence (119,300 ± 14800 kyr for CSm), with deposition occurring into early to mid MIS3 (48,700 ± 4000 for BeSm [PLSsm].3 and 38,500 ± 5800 kyr for UBSm.6)18. The lowest layer studied here (SSLm [Usm].5) yielded an OSL age of 67,900 ± 5150 kyr18.

In the middle and lower layers of the outer stratigraphic sequence, lithic tools are consistent with the Middle Palaeolithic techno-complexes. The knapping technique follows discoid reduction sequences, although a significant increase of laminar flakes coming from bipolar Levallois cores can be detected at SSLm.5–6 (MIS 4). Lithic tools belonging to the Upper Palaeolithic were identified from CHm.5 (unite D of Waechter10; see Collcut and Currant19 for correlations). In the inner sector, level IV corresponds to a Mousterian horizon characterized by the use of flint and fine-grained sandstone and to a lesser extent quartzite, quartz and dolomite. These materials are usually exploited following Levallois and discoid reduction sequences. In some cases, the obtained flakes are configured as scrapers, side-scrapers and denticulates. A significant change can be detected at level III, which is characterized by a blade technology, plain retouch and the configuration of artefacts that could be classified into the Upper Palaeolithic techno-complexes with diagnostic pieces attributable to the Solutrean and Magdalenian20,21.

The faunal record in Gorham's Cave is typically European (i.e., without African influences) and fairly constant in taxonomical composition through the sequence with no marked fluctuations of species per archaeological units, especially in the case of macro-mammals22. The majority of identified ungulate remains belong to two species – Cervus elaphus and Capra ibex. This apparent stability of the environment surrounding the cave supports the hypothesis that southern Iberia did not suffer the extreme cold of glaciations or the aridity potentially generated by it. Only the occurrence of Grey Seal (Halichoerus grypus) registered by Sutcliffe in the D unit (CHm in Currant system; see Collcut and Currant19 for correlations) can be interpreted as punctual evidence of a cold phase since this species has never been previously recorded so far south22; this presence may simply reflect conditions to the north that may have forced some marine species south and not actual conditions on site. The amphibian and reptile assemblages from the inner part of the cave involve at least 24 taxa, including newts, toads, frogs, tortoises, turtles, lacertid and scincid lizards, geckos and several snakes. These findings show an increase in the atmospheric temperature range during the latest Pleistocene, mainly due to lower winter temperatures23. The largest assemblage in the outer area comes from LBSmcf.11, which yielded 21 species with the southern spadefoot toad (Pelobates cultripes) as the most frequent taxa24. The small mammal record is remarkably stable with five dominant species – Oryctolagus cuniculus, Apodemus sylvaticus, Eliomys quercinus, Microtus brecciencis and Pitymys (Microtus) duodecimcostatus. In addition to these taxa, a selection of other species occurs in lower proportions though widely distributed through the stratigraphic sequence25.

Finally, the excavation works in the outer area produced a rich and diverse avifaunal assemblage, including at least 90 species (seabirds, ducks, birds of prey, partridges, waders, pigeons, swifts, crows and small passerines)26. These taxa are especially concentrated on a relatively narrow section of the overall stratigraphic sequence (LBS –Lower Bioturbated Sands). A typical core assemblage of common taxa is apparent throughout the sequence, consisting of partridge (Alectoris sp.), chough (Pyrrhocorax sp.), Common/Pallid Swift (Apus apus/pallidus) and especially, Rock/Stock Dove (Columba livia/oenas)26.