PLEISTOCENE AND HOLOCENE HUNTER-GATHERERS IN IBERIA AND THE GIBRALTAR STRAIT:
THE CURRENT ARCHAEOLOGICAL RECORD
differences can be explained as laboratory errors.
Thus, for example, the different dates for Level
XVII (53,400 ± 1300 BP, Oxa-20318, charcoal; and
>58,500 BP, OxA-20319, charcoal) and for Level
XIF (36,500 ± 830 BP, AA 37882, AMS charcoal;
and 34,380 ± 670 BP, AA 37883, AMS) were obtained from a single sample that was divided up.
Other cases can be regarded as inconsistent,
such as (1) the three dates obtained for Level VI
with results between 44 and 40 ky BP that do not
match the chronological sequence of the occupation; and (2), those for Level XIX, for which the
new determinations (30 ky BP) contradict the ﬁrst
However, the date for Level III (12,050 ± 130
BP, AA29664, AMS bone) is only atypical. It ﬁts in
the archaeological sequence and the samples have
passed the stress tests carried out in speciﬁc studies (Jordá Pardo et al., 2009; Maroto et al., 2011).
Stratigraphically, it may be supposed that the sequence entered markedly colder conditions after
Level VI, which may correspond to H3c (c. 30 ky
BP). The new dates obtained for Level III (19,300
± 100 and 19,310 ± 80 14C ky BP and 20,810
± 110 14C BP), performed within a monographic
project involving a critical reappraisal of many of
the dates obtained in Iberia, support its validity.
However, other clearly aberrant results, such as
one recently obtained for Level III, 3640 ± 90 BP,
may be explained by the intrusion of Holocene
charcoal (Maroto et al., 2011) or the presence of a
very atypical Upper Paleolithic industries.
In this way, radiometric coherence is observed
in the dates around 20 ky BP for the end of the sequence. They were obtained in different laboratories,
using different pre-treatment methods (including
ultraﬁltration) and display C13 values that conﬁrm
the quality of the sample (Maroto et al., 2011). Although many of the dates thought to be recent have
been put back in time, in general terms El Esquilleu
is still within an increasingly select group.
However, some unknown issues cannot be
ruled out, such as a possible contamination of
the samples owing to post-depositional processes
or percolation problems. T aphonomical studies
(Yravedra and González Castanedo, 2013) have
suggested that the dates may have been obtained
from bones which had not been handled by humans, and which are therefore not archaeological
material. Methodologically (i.e., De la Rasilla and
Santamaría, 2013), the limitations of the radiometric method itself have been pointed out, because
of calibration deﬁciencies (Jöris et al., 2011), and
the divergent results caused by the speciﬁc treatment and analytical protocols (Bird et al., 2010).
Technologically (Vaquero, 2013), other studies based on the nature of the lithic assemblage
(whose expedient and indeterminate character
has been highlighted) suggest that Level III could
be a facies with an atemporal cultural attribution.
In any case, a relativist position of the dates can
be used, where, independently of their exact result, their relative position in the sequence can be
considered (Carrión et al., 2013). In addition, the
internal analysis of the industries and their relationship with the environment in chaîne opératoire terms provides interesting information about
changes in the relationship between the group and
their surroundings (Carrión et al., 2008).
El Esquilleu is also special because its sequence
starts at an early date. There are few sites dated
before 40-45 ky BP in the Cantabrian Mousterian. The classic chronologies of Castillo Level 22,
Pendo XVII and Lezetxiki V have been seen to be
disputable and older dates are very rare, with only
El Sidrón (c. 50 ky BP; De la Rasilla et al., 2013)
and in a nearby region, Cueva Corazón (96.95 ky
BP, by TL, Díez et al., 2008). Most of the occupations that are known are concentrated in a time
near the late Mousterian: Mirón, Covalejos, Arrillor, Sopeña, Morín, Amalda and Axlor (Hoyos et
al., 1999; Sanquino and Montes, 2005; Straus and
González Morales, 2001; Maroto et al., 2011, etc.).
An attempt has been made to explain this circumstance by the limitation of the radiocarbon method itself (Santamaría and de La Rasilla, 2013), as
the risk of rejuvenating the result increases exponentially with an increase in the age of the sample.
The litho-stratigraphic study divided the sequence into four sections according to their composition and the agents involved in their formation, by
integrating taphonomic and geo-archaeological criteria, X-Ray diffraction, environmental scanning electron microscopy, and thermoluminescence (Jordá,
2008). From bottom to top, these four sections are
ESQ-D (Levels XXXI to XLI), ESQ-C (Levels XII
to XXX), ESQ-B (Levels I to XI) and ESQ-A (covering breccia and speleothems; the cave, which was
partially ﬁlled, was initially sealed by this large formation; Jordá Pardo et al., 2009).
The human occupation is located in the central
Units B and C. Unit C coincided with sedimentation
in the rock-shelter by diffuse run-off; the upper central Unit B consists of clasts and frost-shattered rocks