# Changes in lithic raw material and technological management during the Mesolithic: a view from El Mazo (Northern Iberia)

Diego Herrero-Alonso, Natividad Fuertes-Prieto, Antonio Tarriño, David Cuenca-Solana, Asier Garcia-Escarzaga, Jorge Calvo Gómez, Igor Gutiérrez-Zugasti

► To cite this version:

Diego Herrero-Alonso, Natividad Fuertes-Prieto, Antonio Tarriño, David Cuenca-Solana, Asier Garcia-Escarzaga, et al.. Changes in lithic raw material and technological management during the Mesolithic: a view from El Mazo (Northern Iberia). Archaeological and Anthropological Sciences, 2025, 17 (6), pp.127. 10.1007/s12520-025-02225-3. hal-05106949

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# Changes in lithic raw material and technological management during the Mesolithic: a view from El Mazo (Northern Iberia)

Diego Herrero-Alonso<fnref n="1" />,<fnref n="2" />,<fnref n="3" /> · Natividad Fuertes-Prieto<fnref n="4" /> · Antonio Tarriño<fnref n="5" /> · David Cuenca-Solana<fnref n="6" />,<fnref n="7" /> · Asier García-Escárzaga<fnref n="8" /> · Jorge Calvo-Gómez<fnref n="7" />,<fnref n="9" /> · Igor Gutiérrez-Zugasti<fnref n="6" />

Received: 15 March 2024 / Accepted: 9 April 2025

© The Author(s) 2025

## Abstract

This study investigates the lithic industry at the Mesolithic shell midden site of El Mazo (Andrín, Asturias), on the Asturian coastline in Northern Iberia, focusing on resource management, production strategies, and mobility patterns of the last hunter-gatherer-fishers. El Mazo provides a unique opportunity to examine lithic resource use across the Early-Middle Holocene transition, with a particular emphasis on the dynamic of the 8.2 ka climate event. Raw material analysis reveals that most lithic resources originated locally (< 30 km), although some were transported from distances exceeding 250 km, indicating extensive mobility and exchange networks. Technological trends (bladelet production) and typological changes in microliths (backed points and geometric forms) across the extensive stratigraphy connect this sequence to broader Mesolithic developments in both Iberian and European contexts. The occurrence of trapezoids and microburins at the base of the stratigraphic sequence links this assemblage to the European Second Mesolithic and the Iberian Geometric Mesolithic. The 8.2 ka event stands out as a pivotal period marked by increased mobility and intensified long-distance contacts, influencing both raw material procurement and armature typology. However, post-8000 cal BP stratigraphic units indicate a narrowing of lithic resource acquisition ranges, alongside the introduction of new geometric forms such as triangles and a novel retouch technique (“double bevel”). This highlights diachronic changes around 8000 cal BP that align with broader Iberian trends. These findings challenge traditional conceptions of the Asturian culture as isolated; instead revealing complex adaptive strategies, dynamic territorial organization, and extensive connectivity among Mesolithic groups in northern Iberia.

**Keywords** Mesolithic · Asturian · Lithic technology · Raw material supply · *Chaîne opératoire* · Mobility

<figure><img src="image_2.png" /></figure>

<footnote>Diego Herrero-Alonso
diego.herrero.alonso@uvigo.es</footnote>

<footnote n="1">¹ Departamento de Historia, Arte e Xeografía, Universidade de Vigo, Campus Universitario As Lagoas s/n. 32004, Ourense, Spain</footnote>

<footnote n="2">² Grupo de Estudos de Arqueoloxía, Antigüidade e Territorio (GEAAT), Ourense, Spain</footnote>

<footnote n="3">³ Departamento de Geologia, Centro de Geociências, Universidade de Trás-Os-Montes e Alto Douro, Quinta de Prados, 5000 - 801 Vila Real, Portugal</footnote>

<footnote n="4">⁴ Departamento de Historia, Facultad de Filosofía y Letras, Universidad de León, Campus de Vegazana, s/n 24071, León, Spain</footnote>

<footnote n="5">⁵ Departamento de Geografía, Prehistoria y Arqueología, Universidad del País Vasco/Euskal Herriko Unibertsitatea</footnote>

<footnote>(UPV/EHU), Calle Francisco Tomás y Valiente, s/n. 01006, Vitoria-Gasteiz, Spain</footnote>

<footnote n="6">⁶ Instituto Internacional de Investigaciones Prehistóricas de Cantabria (Universidad de Cantabria, Gobierno de Cantabria, Banco de Santander), Edificio Interfacultativo, Avda. Los Castros n° 52. 39005, Santander, Spain</footnote>

<footnote n="7">⁷ Centre de Recherche en Archéologie, Archéosciences, Histoire (CReAAH), CNRSUMR 6566, Université de Rennes, Rennes, France</footnote>

<footnote n="8">⁸ Department of Prehistory and Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona, Bellaterra, Spain</footnote>

<footnote n="9">⁹ University of Oslo, Museum of Cultural History, Oslo, Norway</footnote>
Introduction

The Mesolithic in Europe is defined by the variability of
strategies adopted by hunter-gatherer-fisher groups under
the changing climatic conditions of the Pleistocene-
Holocene transition (Mason 2000; Holst 2010; Mannino
et al. 2011). Within this variability, the Atlantic coast of
Europe is mainly characterised by the existence of large
shell middens, generated as a result of intensive exploita-
tion of coastal areas. This type of settlement is particularly
well known in areas such as Denmark, United Kingdom,
France, Portugal, and Spain (Andersen 2007; Milner et al.
2007; Dupont et al. 2009; Gutiérrez-Zugasti et al. 2011).

Northern Iberia is one of the areas with a high density
of shell middens, in particular, in the area related to the
so-called Asturian culture. Here, more than 130 Mesolithic
shell midden sites have been identified (Fano 1998, 2019;
Arias et al. 2015, 2021). Recent archaeological excava-
tions have found in situ hearths and post holes suggesting
a residential use of the shell middens (Gutiérrez-Zugasti
et al. 2020). From a chronological perspective, the Astu-
rian lasted approximately between 10.7 and 6.8 ka cal BP
(García-Escárzaga et al. 2017, 2019). Mesolithic hunter-
gatherer-fishers lived under temperate climatic conditions
in northern Iberia, although short colder phases have also
been identified (Mayewski et al. 2004; Rohling and Pálike
2005; Thomas et al. 2007). This is the case of the 8.2
ka cold event, whose severe conditions caused changes in
the availability of some species of marine fauna (García-
Escárzaga et al. 2022b) and could even be related to the
arrival in northern Iberia of exogenous populations from
Eastern Europe (Allentoft et al. 2024). The significant
impact of this abrupt climate change on population dynam-
ics, settlement and subsistence strategies has also been
observed in other areas of Iberia (Alday Ruiz and Cava
Almuzara 2009; Utrilla et al. 2009; González-Sampériz
et al. 2009; Bicho et al. 2010; Pereira and Carvalho 2015;
Soto et al. 2016; Bicho and Cascalheira 2018; Fernández-
López De Pablo et al. 2023).

From a subsistence perspective, Mesolithic societies in
northern Iberia have been linked to the exploitation of a
wide variety of marine and terrestrial resources (Vega del
Sella 1923; González Morales 1982; Clark 1983). Recent
investigations, including the excavation of new sites, have
reported the exploitation of land mammals, especially red
deer, roe deer and wild boar (Marín Arroyo and González
Morales 2009; Marín-Arroyo 2013; Marín-Arroyo et al.
2020), as well as coastal resources that include abundant
molluscs together with fish, echinoderms and crusta-
ceans, which show a significant exploitation of the inter-
tidal area (Gutiérrez-Zugasti et al. 2011, 2016; Fano et al.
2013; Álvarez-Fernández 2015; García-Escárzaga 2020;

García-Escárzaga and Gutiérrez-Zugasti 2021; García-
Escárzaga et al. 2022b). The analysis of carbon and nitro-
gen isotopes in human bones showed the consumption of
similar amounts of terrestrial and marine proteins (Arias
2006). This activity pattern has been related to reduced
mobility and the development of territoriality (González
Morales 1982; Arias 2006). This seems to be also reflected
in the production and use of items with significant iden-
tity value at Mesolithic sites, such as personal ornaments
(Rigaud and Gutiérrez-Zugasti 2016).

While research on the Asturian Mesolithic has focused on
environmental conditions and food procurement, the technol-
ogy is poorly known. Since the beginning of research on the
Asturian in the first quarter of the twentieth century, shell mid-
dens have been associated with the presence of a distinctive
lithic artefact, called the"Asturian pick"(Vega del Sella 1923),
an instrument knapped on quartzite and probably related to
the exploitation of limpet shells (Cuenca-Solana et al. 2018).
Asturian lithic assemblages have been characterised by the
predominance of quartzite, the large number of flakes and
the scarcity of laminar/microlaminar artefacts (mostly in
flint when they are present) and retouched tools (Clark 1972;
González Morales 1982, 1995; Straus and Clark 1986). How-
ever, the excavations carried out at El Mazo have considerably
changed this view, with a more discreet use of quartzite in
favour of different varieties of chert, radiolarite or flint, the
presence of laminar/microlaminar blanks and a greater number
of retouched artefacts, including microliths, such as geometrics
(Fuertes-Prieto et al. 2021). At the same time, the Asturian
bone industry is scarce, and defined by the presence of awls,
bi-pointed hooks, perforated batons and antler points (Vega
del Sella 1923; González Morales 1982, 1995; Clark 1983).

Regarding lithic raw materials, most of the available
information is based on visual observations without any
characterization of provenance. In general, there is a clear
predominance of quartzite at sites such as La Riera (Straus
and Clark 1986), Mazaculos II, Cuesta Pimiango, and Sierra
Plana (Arias Cabal 1991), with percentages ranging from
66.7% (Level 30 at La Riera) to 88% (Cuesta Pimiango).
The increased use of quartzite in the area from the Azilian
period (ca. 13–11 ka cal BP) has previously been linked to
local procurement and reduced mobility (González Morales
et al. 2004; Arias Cabal and Fano 2009). However, there are
sites, such as El Mazo, where quartzite is much less frequent
than flint (Fuertes-Prieto et al. 2021).

Although significant advances have been made in under-
standing the lifestyles of the last hunter-gatherer populations
along the northern Iberian coast over the past few decades,
several important aspects remain to be defined, such as the
impact of environmental changes on the management of
lithic chañes opératoires (supply, production, and retouch-
ing). El Mazo rockshelter (Asturias, northern Iberia) is one

<figure><img src="image_3.png" /></figure>
of the few Iberian sites with continuous occupation through-
out the Early and Middle Holocene, spanning a period before
and after the 8.2 ka cal BP event. In this paper, we present a
high-resolution study of the lithic assemblage, highlighting
changes in human mobility, economy, culture and behaviour
in this region before, during and after this climatic event.

El Mazo site

**Geological and geographical context**

Geologically, El Mazo is located in the Ponga Unit of the Cantabrian Zone (CZ), as outlined by Julivert (1971). The rock-shelter is situated in a rocky outcrop within the upper member of the Picos de Europa Formation. The ZC is characterised by a significant presence of sedimentary materials of Palaeozoic age, predominantly from the Cambrian to Carboniferous periods, with a gradual gap to the east affecting Ordovician and Silurian rocks.

Recent geological studies in the ZC have defined vari-
ous formations with chert and radiolarite of Devonian and
Carboniferous chronologies (Herrero-Alonso 2018; Herrero-
Alonso et al. 2021b). Furthermore, El Mazo is in proximity
to the boundary with the Basque-Cantabrian Basin, where
another set of recognized flint varieties is present (Tarriño
et al. 2015).

The site of El Mazo is located in the town of Andrín
(Municipality of Llanes), in eastern Asturias (Spain), on the
coastal platform and approximately 1 km from the present
coastline (Fig. 1). This platform played a crucial role during
the Mesolithic as a corridor for east–west mobility. At the
onset of the Mesolithic, the sea level was lower and gradu-
ally rising until reaching a position similar to today around
8,000 years ago (Leorri et al. 2012). Consequently, the dis-
tance from El Mazo to the coastline during its occupation
was no more than three kilometres (García-Escárzaga et al.
2022b).

**Description and stratigraphy**

The rock-shelter is about 18 m long and 7 m deep. The
archaeological excavation took place between 2009 and
2017, identifying stratigraphic units (SUs) from the Meso-
lithic and post-Neolithic occupations. The Mesolithic units
studied here were documented in three different areas of the
site (inner, outer and north) (Gutiérrez-Zugasti and González
Morales 2013; Gutiérrez-Zugasti et al. 2018).

The excavation in the inner area of the rock-shelter
was carried out in Squares V15 and V16 (2009, 2010 and
2013), and the resulting profile was sampled in Squares

X15 and X16 (2012) in a limited extension (2 m in the
east-west axis ×0.25 m in the north-south axis). Ten
shell midden stratigraphic units were identified in the
2009-2010 campaigns: SUs 100/101, 102, 103, 103.1,
104, 105, 106, 107, 108 and 109. After a careful examina-
tion of the stratigraphy during the 2012 fieldwork, it was
possible to identify that some of these units included other
units or depositional events. Unit 100/101 is a thick shell
matrix formed by several units (100, 101 A, 101B, 101 C,
101D, 117, 101.1 A, 101.1B and 119). Units 102 and 106
are brecciated deposits composed of shells mixed with
carbonate, while Unit 104 is a fire structure (hearth) mixed
with shells. Unit 103 includes also units 112 A, 112B and
112 C, and they are defined as shell matrix alternating
with charcoal layers; Unit 103.1 is a shell matrix remnant
only present in the eastern part of Square V15; and Unit
105 (characterised by a larger amount of sediment relative
to shell) includes two additional units: 113 and 120 (both
shell matrix). Finally, Unit 107 (a thick shell matrix) is
composed of four additional units: 110, 111, 114 and 115,
while Unit 122 is a hearth, probably related to the occupa-
tion of Unit 107. Below, Unit 108 represents the base of
the shell midden and Unit 109 is a yellow clay unit with
limited archaeological materials, probably belonging to
the first occupations of the rock-shelter.

In the outer area, located in front of the rock-shelter, 4 m²
were excavated in Squares S9, S10, T9 and T10. Squares S10
and T10 produced Mesolithic units. Below two subsurface
(probably disturbed) stratigraphic units (SUs 1A and 1B),
two intact Mesolithic units were identified. Unit 3 was a shell
midden unit while Unit 1C, immediately above Unit 3, was
composed of dark brown clay with lithics, mammal bones and
pebbles.

Extensive excavations were carried out in the north area of
the site between 2013 and 2017. Most of the units identified
in this area belong to post-Neolithic occupations and only in
Square Z12 was it possible to reach the top of the Mesolithic
shell midden, identified as Unit 803.

**Chronological context**

An extensive analysis of the chronology of the site has been
recently published in García-Escárzaga et al. (2022a, b), based
on 65 radiocarbon dates from the inner area (Fig. 2). The
Bayesian modelled sequence placed the shell midden forma-
tion in the Early and Middle Holocene, between 9.0 and 7.4
ka cal BP. Units from the outer area were ascribed to the final
part of the Mesolithic occupation based on radiocarbon dates
from Units 3 (7,630 cal BP) and 1C (7,180 cal BP). In the
north area, Unit 803 was ascribed to the Mesolithic based on
material culture.
<figure><img src="image_4.png" /><figcaption>**Fig. 1** At the top: Geographical location map of El Mazo and other Holocene sites mentioned in the Cantabrian Region. At the bottom: On the left, a general excavation plan showing the location of the test pits. On the right, the stratigraphic sequence in the inner pit</figcaption></figure>

**Materials and methods**

The lithic materials studied here come from the test pits and samplings carried out in the three excavation areas of the

site, including a total of 1,967 artefacts. These make up the entire lithic collection recovered during the excavations in 2009, 2010 and 2012 (Table 1). The stratigraphic units excavated during those campaigns have been grouped into three

<figure><img src="image_5.png" /></figure>
phases based on previous stratigraphic, chronological and climate studies at the site (García-Escárzaga et al. 2022a, b): before the 8.2 ka event (9,000—8,300 cal BP), during the event (8,300—8,075 cal BP), and after it (8,075—7,180 cal BP) (Table 1).

All sediments from the site were sieved using a mesh size of 2 mm, which made it possible to recover small elements. One of the characteristics of the material from El Mazo is the abundance of debris and fragments, a high percentage of which are smaller than 5 mm. In many cases, it was not possible to identify the raw materials of these fragments due to their small size. While they will be considered in the final counts for reconstructing the *chaînes opératoires* due to their technical value, they will not be employed for the detailed description of the industry.

The study of the lithic industry has been carried out using the conceptual framework of the"chaîne opératoire" which has allowed the reconstruction of the technique sequence of the knapping processes (Pelegrin et al. 1988; Karlin 1991; Audouze and Karlin 2017). The "chaîne opératoire" concept is used in a general way, and "operational scheme" is employed to describe the conceptual schemes developed.

The raw materials have been described and identified following the methodological proposal of Antonio Tarriño and Xavier Terradas (Tarriño and Terradas 2013), used in previous studies on other sites in the Cantabrian Mountains (Herrero-Alonso et al. 2021b). In the present study, a macroscopic analysis has been applied, both visually and with a stereomicroscope, to organise the industry according to groups of distinct raw materials. For this purpose, characteristics such as matrix texture, impurities, and inclusions have been used (Herrero-Alonso 2018). Once the groups were formed, a representative sample was selected from each of them, which was studied in thin sections (eight samples in total from different lithologies at El Mazo). Their analysis was based on the description of orthochemical and allochemical elements, authigenic minerals, and relict minerals, following the proposal of Folk (Folk 1980) and other previous works (Tarriño and Terradas 2013; Herrero-Alonso 2018; Herrero-Alonso et al. 2021b). Based on these attributes, it was possible to identify the provenance of most of the flint, chert and radiolarite, using the *LegioLit* lithothephe in the University of León as a comparative collection (Herrero-Alonso et al. 2018).

For the technological study, we first organised the material into different technological groups: cores (Gr.4), nodules (Gr.0) and blanks. Subsequently, blanks were subdivided into different categories according to their position in the production process and/or technical characteristics: flakes (Gr.1), laminar blanks (Gr.2), by-products (Gr.3), indeterminate (Gr.5), debris (Gr.6) and blanks with retouch or linked to their production (Gr.7). In addition, other attributes such as butt (type, preparation, and angle), the orientation of

the negatives, measurements (height, width, thickness, and weight), fractures and knapping accidents have also been considered (Fuertes-Prieto 2010). For the description of the retouched pieces, the typology established by Fortea (1973) has been used, as it is the one most commonly used for Mesolithic collections in Iberia, facilitating comparisons with other sites.

## Results

### Raw material supply

El Mazo shows a wide variability of raw materials, divided into three main groups: quartzite, quartz, and the group of chert, radiolarite, and flint. The description of the latter group has been systematically organized, considering the distance from the site to the nearest outcrop, following the proposal of Tarriño et al. (Tarriño et al. 2016). This method organizes resources based on their proximity to the site: i) local resources (< 30 km), discriminating between proximate (< 15 km) and distant (15–30 km) resources; ii) regional resources (30–120 km), again divided between proximate (30–60 km) and distant (60–120 km); and iii) tracer flints, from extra-regional areas (> 120 km) (Supplementary file 1).

### Local resources

**Alba radiolarite** Radiolarite crops out in the Alba Fm. (Lower Carboniferous) (Wagner et al. 1971) and is one of the most frequently found materials in Palaeolithic and Mesolithic sites across the Cantabrian Zone, due to its wide distribution and abundance in the region. The radiolarite is located mainly in the middle member (Lavandera), with centimetric to decimetric bedded chert intercalated with shales, featuring parallel lamination, presence of radiolarians and a wide range of colours: reds, greens, greys, and blacks (Herrero-Alonso et al. 2021b) (Fig. 3 and Fig. 4). Radiolarite crops out as blocks formed by natural fracture planes and host rock lamination, and these can easily be collected from the bedrock. Additionally, collection in marine and fluvial contexts is also identified, with rounded cortex showing initial hertzian fractures.

Radiolarite also crops out in the upper member (Canalón) of the Alba formation, as sub-spherical nodules (5–20 cm) included in massive reddish limestones. These nodules are characterised by the presence of radiolarians, occasional crinoids and the absence of lamination (Figs. 3 and 4). Extracting these nodules from the bedrock is challenging due to their strong cohesion. For this reason, they can only be collected in areas where erosion has removed the limestone,
<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /></figure>
►Fig. 2 Radiocarbon-based chronology for the midden site sequence in El Mazo cave (García-Escárzaga et al. 2022b), modelled using OxCal v4.4.2, the radiocarbon calibration curves IntCal20 and Marine20, and ΔR values published by García-Escárzaga et al. 2022a for correcting the marine reservoir effect. The interval of each unit was modelled using all radiocarbon dates available for each unit

leaving the nodules exposed, such as along the coast near El Mazo.

Radiolarites from both middle and upper members are available within 5 km from El Mazo, with the Lavandera variety being the most frequent before and during the 8.2 ka event. The Canalón variety is scarce, with only two pieces per phase (supplementary 2). After the 8.2 ka event, radiolarite acquisition shifted, leading to a more balanced distribution of the two types. Despite being locally available, radiolarite initially comprised only 10% of materials, but its use increased to 21.4% during the 8.2 ka event and reached 34.2% in later phases (Fig. 5 and supplementary 1).

**Pendueles chert** This Upper Carboniferous chert variety outcrops exclusively on the Asturian coast less than 5 km in a straight line eastward from the site. This makes Pendueles chert an excellent mobility marker. The only outcrop known so far is about 100 m thick, interbedded with different strata of breccias, calcarenites, marls, shales, and chert (Martínez García et al. 1971; Coello-Monroy 1996). Identified in two thin sections from the site, this variety is characterised by parallel lamination, predominantly dark tones and a significant amount of siliceous sponge spicules. When weathered, Pendueles chert can exhibit yellowish-brown hues (Herrero-Alonso et al. 2021b) (Figs. 3 and 4). Acquisition took place both at the outcrop itself and in secondary marine contexts. The percentage of Pendueles chert increased over time, from 7.5% before the 8.2 ka event to 13.0% in the later phase (Fig. 5). However, these percentages remain relatively low, considering the proximity to the site.

**Portillas chert** The chert from the Portillas Fm. (Devonian) crops out in a small area between the Deva and Cares valleys, in the Picos de Europa (Cantabrian Mountains) acting as a territorial marker for mobility (Marquínez 1978; Rodríguez Fernández et al. 1994; Herrero-Alonso 2018; Herrero-Alonso et al. 2021b). The geographical proximity of El Mazo to the mouth of these rivers (15–20 km east of the site) accounts for the high relative percentage of Portillas chert at the site. Along the river terraces up to the coast, centimetre to decimetre sized nodules are abundant, and they were exploited by prehistoric groups. Although the cortical index is not very high, pieces with secondary cortex (fluvial catchment) and primary cortex have been found. In the latter case, the chert was collected near to outcrops, likely in areas

around the Mesolithic site of La Calvera (< 30 km from El Mazo), where evidence suggests that this variety was also exploited (Díez Castillo 1996; Columbu et al. 2023) (Fig. 1). Portillas chert is characterised by its glassy lustre, dolomite rhombs, and notable amounts of detrital minerals. At El Mazo, distinct patterns emerge regarding the frequency of this chert. In the pre-and post- 8.2 ka phases, the percentage remained relatively stable (4.0%– 3.4%). However, during the 8.2 ka event, the percentage increased to 9.5% (Fig. 5).

**Quartzite** Quartzite is a rock frequently used at prehistoric sites in the Cantabrian region. This raw material has generally received limited attention, often being grouped into a single heterogeneous category. However, recent efforts have been undertaken to describe the diverse quartzite varieties present in the Cantabrian Region more thoroughly, allowing for nuanced distinctions based on texture (Prieto et al. 2021). Here, the quartzite will be treated as a unitary group, unlike chert and flint, which are further categorised into varieties. Therefore, the quartzite group may be a little oversized with respect to the others.

At El Mazo, the quartzite was collected in secondary contexts. The presence of a rounded cortex suggests that provenance may be associated with conglomerates or marine and fluvial contexts. It is difficult to establish the collection point as numerous outcrops of varied types exist in the area, although procurement probably took place near the site due to its widespread availability.

The proportions of quartzite exhibit significant variations across the three phases under examination. Notably, there is a discernible decline in importance, from 52.7% before the 8.2 ka event to 11.9% during the 8.2 ka event and to 4.7% after the end of this event (Fig. 5).

**Quartz** The study of quartz in archaeological sites is, like quartzite, at a very early stage, and for that reason it is usually grouped in heterogeneous assemblages under a single denomination (de Lombera Hermida and Rodríguez-Rellán 2022). In the case of El Mazo, as in other assemblages, auto-morphic quartz has been differentiated from xenomorphic quartz (rock crystal and milky, respectively), but it is not possible, for the moment, to make any concrete inference about its provenance. Nonetheless, considering that it occurs naturally in the vicinity of the site, we have chosen to regard it as a local raw material. The rock crystal from El Mazo is collected exclusively in primary position, with the crystal faces preserved in the pieces. No evidence linked to collection in a derived position has been detected, either in the rock crystal or in the milky quartz. The percentage of quartz is more homogeneous in the pre-and post-event phases 8.2 ka (16.7%– 12.7%) than during the event (1.7%) (Fig. 5).
<table><caption>**Table 1** Stratigraphic units (SU) and their abundance, organized by chronological phases and excavation areas. The coloured graphs illustrate the percentage of items per SU by phase</caption><thead><tr><th>Phase</th><th>Area</th><th>Context</th><th>SU</th><th>Abundance</th><th>Total items</th></tr></thead><tbody><tr><td rowspan="10">Post 8.2 ka event</td><td rowspan="2">Outer pit</td><td>Sedimentary layer - bioturbation</td><td>1C</td><td>4</td><td rowspan="10">1377</td></tr><tr><td>Shell-midden layer</td><td>3</td><td>340</td></tr><tr><td rowspan="5">North pit</td><td>Shell-midden layer</td><td>803</td><td>4</td></tr><tr><td>Shell-midden layer</td><td>100</td><td>89</td></tr><tr><td>Shell-midden layer</td><td>100/101</td><td>743</td></tr><tr><td>Shell-midden layer</td><td>101A</td><td>8</td></tr><tr><td>Shell-midden layer</td><td>101B</td><td>22</td></tr><tr><td rowspan="5">Inner pit</td><td>Shell-midden layer</td><td>101C</td><td>9</td></tr><tr><td>Shell-midden layer</td><td>101D</td><td>16</td></tr><tr><td>Shell-midden layer - hearth</td><td>101.1A</td><td>6</td></tr><tr><td>Shell-midden layer</td><td>101.1B</td><td>26</td></tr><tr><td>Shell-midden layer</td><td>119</td><td>1</td></tr><tr><td rowspan="6">8.2 ka event</td><td rowspan="6">Inner pit</td><td>Shell-midden carbonated layer</td><td>102</td><td>18</td><td rowspan="6">243</td></tr><tr><td>Shell-midden carbonated layer</td><td>106</td><td>43</td></tr><tr><td>Shell-midden layer</td><td>116</td><td>2</td></tr><tr><td>Shell-midden layer</td><td>103</td><td>46</td></tr><tr><td>Hearth</td><td>103.1</td><td>7</td></tr><tr><td>Shell-midden layer</td><td>104</td><td>5</td></tr><tr><td rowspan="5">Pre 8.2 ka event</td><td rowspan="5">Inner pit</td><td>Shell-midden layer</td><td>112</td><td>15</td><td rowspan="5">347</td></tr><tr><td>Shell-midden layer</td><td>113</td><td>23</td></tr><tr><td>Sedimentary layer with shells</td><td>120</td><td>4</td></tr><tr><td>Shell-midden layer</td><td>105</td><td>189</td></tr><tr><td>Shell-midden layer</td><td>110</td><td>5</td></tr><tr><td rowspan="5">Pre 8.2 ka event</td><td rowspan="5">Inner pit</td><td>Shell-midden layer</td><td>111</td><td>7</td><td rowspan="5">347</td></tr><tr><td>Shell-midden layer</td><td>107</td><td>223</td></tr><tr><td>Sedimentary layer</td><td>114</td><td>2</td></tr><tr><td>Shell-midden layer</td><td>115</td><td>10</td></tr><tr><td>Sedimentary layer</td><td>108</td><td>76</td></tr><tr><td>Pre 8.2 ka event</td><td>Inner pit</td><td>Sedimentary layer</td><td>109</td><td>19</td><td></td></tr><tr><td>Pre 8.2 ka event</td><td>Inner pit</td><td>Hearth (shell midden base)</td><td>122</td><td>5</td><td></td></tr></tbody></table>

## Regional resources

**Piloña flint** This variety outcrops almost exclusively in the fluvial valley of the river Piloña (Asturias), a tributary of the Sella, and it is linked to the Pudinga de Posada formation (Oviedo basin). This flint is characterised by a yellowish colour, with the presence of detrital quartz and *Lacazina* sp. as the most characteristic fossil (Tarriño et al. 2013) (Fig. 3). The identified cortex is secondary in all cases, exhibiting fluvial marks on most of the pieces. Collection probably occurred about 30–40 km west from El Mazo, therefore, in a proximate regional context. Piloña flint displays a very similar pattern in the pre-and post- 8.2 ka event phases, with very low percentages (0.9–0.6%). However, during this event, the percentage increases to 4.5% (Fig. 5).

**Urgonian flint** This flint is one of the least known flints in the Basque-Cantabrian Basin. It outcrops in the central sector of the Cantabrian Mountains and has a wide geographical distribution. The catchment radius of this raw material can range from 40 to 120 km east from El Mazo (i.e. near-regional considering the minimum distance). The bedrock is predominantly limestone, formed during the Lower Cretaceous in shallow marine platform contexts, mostly of reef type, although not exclusively. Urgonian flint shows great variability because of the different formation processes, and its identification is a complex task due to the lack of specific studies (Tarriño et al. 2015; Bustillo et al. 2017). In the case of El Mazo, slightly translucent flint with the presence of corals and dolomite and the absence of sponge spicules and sands has been ascribed to this category. At El Mazo
it has not been identified in the older phase, with very low percentages during the 8.2 ka event (1.2%), and decreasing in the later phase (0.4%) (Fig. 5). Identification of flint collection areas was not possible due to the absence of pieces with cortex.

**Monte Picota flint** This flint variety is sourced from a hill at the mouth of the Pas River (Tarriño et al. 2015, 2016). The distance from El Mazo to the best-known outcrops of this formation is approximately 60 km to the east (i.e. near-regional). This translucent flint exhibits porosity, typically cemented by quartzine, and some patination (Herrero-Alonso 2018) (Fig. 3). Only pieces with secondary cortex have been found, and they were probably recovered in marine contexts. Once again, a notable similarity is evident in the percentages observed before (0.6%) and after (0.4%) the 8.2 ka event, with a significant increase during the event (5.8%) (Fig. 5).

**Fito chert** Fito chert (Upper Carboniferous) outcrops as a bedded formation at the headwaters of the Ponga River, a tributary of the Piloña River and, this in turn, of the Sella River (Ginkel 1965). Its distinctive features include lenticular lamination with abundance of bioclasts and dolomite idiomorphs. In the case of El Mazo, all pieces of Fito chert lack cortex, so it is not possible to make inferences about its catchment area. Therefore, procurement could have taken place either in a primary position (around 50 km) or in a secondary position (30–50 km), in any case, in a regional context to the west/southwest of the site. It is not found at El Mazo in the first phase, it is scarce during the 8.2 ka event (2.1%) and very scarce after the event (0.4%) (Fig. 5).

**Piedramuelle flint** This flint crops out near the city of Oviedo, about 90–100 km southwest of El Mazo (distant regional origin). It is an Eocene flint that looks like breccia due to the silicification of lacustrine-palustrine soil (Herrero-Alonso 2018). In El Mazo, all pieces appear in SU 105 (1.7%), formed at the beginning of the 8.2 ka event. None of them display cortex, so the acquisition context is unknown (Fig. 5).

## Tracer resources

**Flysch flint** This flint stands out as one of the prominent flint varieties in the Cantabrian Region, with its nearest outcrops located approximately 130–145 km from El Mazo. Flysch flint is a generic term encompassing various varieties that developed within a turbidite system during the Upper Cretaceous in the Basque-Cantabrian Basin (Fig. 3). Initial studies on this flint were conducted in A. Tarriño's Ph.D thesis (Tarriño 2006). Despite the potential existence of subvarieties within Flysch, such as Kurtzia or Bidache, specific

identification has proven elusive for El Mazo, leading to its classification as a single group. At El Mazo, Flysch flint is relatively prevalent, considering its considerable distance from the outcrops. The abundance of this flint was very low before and after the 8.2 ka event (1.4%–1.3%) but there was a significant increase to 5.8% during the event (Fig. 5).

**Tercis flint** This Upper Cretaceous flint crops out in Dax, located in the French Landes, within the Adour River basin (Odin 2001), approximately 290 km from El Mazo in a straight line. Characterised by dark hues and very fine grain, it is distinguished by the presence of foraminifera, including both benthic and planktonic forms, with the latter, particularly globigerinids, playing a crucial role in its identification (Tarriño et al. 2015) (Fig. 3 and Fig. 4). At El Mazo, two pieces belonging to this flint variety have been identified through thin section analysis, both recovered from SUs dated to the 8.2 ka event (105 and 103.1) (Fig. 5).

## Other raw material groups

In addition to the identified raw materials, there is a substantial number of artefacts for which the origin remains elusive. Various factors contribute to this issue, including the small size of the pieces, the lack of diagnostic elements, and the alterations. The percentage of indeterminate flint/radiolarite/chert increases over time, with 5.5% in the pre-8.2 ka phase, 23.9% during the 8.2 ka event, and 28.9% in the post-8.2 ka phase (Fig. 5).

Notably, a piece of Escalada chert has been identified, although it has not been considered for this study as it was located in a disturbed SU (SU118), which could belong to either the 8.2 ka event or the subsequent phase. This particular raw material is characterised by an intense black colour and the presence of fusulinids (Fuertes-Prieto et al. 2016). While its presence is residual, this piece represents the first time that this raw material has been identified at a Mesolithic site in the Cantabrian region. The closest outcrop, albeit small, is situated approximately 10 km east of El Mazo but it is also found in greater abundance towards the valleys of the Sella and Nalón rivers, to the south-west.

Finally, other less prevalent raw materials, such as sandstone and shale, have been identified in smaller quantities.

## Lithic production

The early stages of the *chaînes opératoires* are represented by two types of remains: (1) blocks and pebbles selected for knapping and transported to the site in their rough form, and (2) blanks extracted during initial knapping sequences, such as cortical (100% cortex on the dorsal face) or first-order flakes (> 75% cortex).
<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>

<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

<figure><img src="image_13.png" /></figure>

<figure><img src="image_14.png" /></figure>

<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>
◄Fig. 3 Archaeological lithic objects: A Pendueles chert with sponge spicules (green arrow) and lamination. B Parallel lamination of Alba radiolarite from the middle member (Lavandera). C and D Radiolaria (green arrow) in a non-laminar matrix typical of the Alba radiolarite, upper member (Canalón). E Homogeneous matrix with sand and sponge spicules of the Flysch chert. F Lacazina sp. from a Piloña flint. G) General homogeneous texture with cemented geodes (green arrow) of Monte Picota flint. H) Globigerinids (green arrow) typical of Tercis flints

Blocks/pebbles from these stages are scarce, fragmented, and sourced from nearby local materials (quartzite, radiolarite, and Pendueles chert). These blocks are more abundant during the most recent phase than during the other two (Table 2). Their fragmented state and low number prevent size estimation, though most are under 4 cm, except for a 12 cm-long Pendueles chert plaque.

Cortical and first-order flakes are scarce and unevenly distributed, comprising only 1.02% of the total collection. The majority are in locally sourced materials, such as quartzite and radiolarite, with no examples of Pendueles chert. Prior to the 8.2 ka event, all cortical flakes are of quartzite. During the 8.2 ka event, there are local and regional flint varieties, including Piloña and Monte Picota. After the 8.2 ka event, a greater variability is evident, with presence of local materials such as quartzite, quartz, and Alba radiolarite (Supplementary file 3).

At El Mazo, a total of 24 cores have been identified and classified into two categories based on the type of blanks produced: flakes and blades/bladelets (Supplementary file 4). Given the procurement patterns described in the previous section, the vast majority of cores belong to local varieties. The only non-local core, classified as tracer, is a Flysch flint core associated with the 8.2 ka event.

The production of laminar blanks primarily follows two operational schemes: unipolar prismatic (parallel extractions) and pyramidal (convergent extractions), both employing a single percussion platform (Fig. 6: 1–4). Knapping is conducted frontally, with well-defined lateral flanks. The natural joint planes and prismatic morphologies of Alba radiolarite and Pendueles chert are frequently exploited, facilitating the initiation of knapping and the maintenance of flanks. Additionally, some cores exhibit basal chipping, likely resulting from being supported on an anvil during percussion. Two knapping qualities have been identified within the laminar schemes. Overall, most cores exhibit regular or adequate production, and similar features are observed in the laminar blanks (Fig. 7: 1–4). However, two cores demonstrate high-quality manufacture (Fig. 6: 1–2). In these cases, the regularity of extractions and the shape of the cornices suggest the use of indirect percussion. Nevertheless, it is not easy to attest the development of highly standardized laminar production as typically referred to in the Geometric Mesolithic

in other Iberian areas and European trends (Gómez-Puche and Fernández López de Pablo, 2024; Soto et al 2023).

Among laminar production, bladelets consistently outnumber blades, with this trend increasing over time. Despite this, no clear differentiation in the intended target between blades and bladelets is evident, as the widths of laminar blanks display a unimodal distribution with an average of 8.2 mm (s.d. = 2.62 mm) (Fig. 8). The dispersion of these widths may be related to the progressive reduction in core size as knapping progresses. Regarding length, no significant differences are observed between the various raw materials. However, blades/bladelets tend to be slightly longer in the earlier phases, with an average length of 18.47 mm (s.d. = 6.5 mm). The proportion between the number of flakes and laminar blanks always favour the former, which are the most frequent in the three phases (Supplementary file 3). This is particularly evident in the pre- and post- 8.2 ka phases, when flakes constitute 70.4% and 68.2% of the target blank assemblage, respectively. However, during the 8.2 ka event, this percentage decreases significantly to 50.9%, bringing it much closer to the proportion of blades and bladelets.

In the case of flake production, three distinct operational schemes have been identified. The first involves unipolar cores, where flakes are extracted perpendicularly to the core's long axis, from the striking platform to the base, covering the entire flaking surface. The second scheme is the use of core-flakes, which employ the ventral face of a thick flake as a striking platform for unipolar, semi-enveloping extractions. The third scheme is characterised by multipolar cores, which lack a hierarchical structure and exploit advantageous angles for knapping without prior preparation.

All flake cores were made from local raw materials, with quartzite predominating in the earlier phases until it was gradually replaced by Alba radiolarite by the end of the sequence. No regional or tracer flint cores have been identified; however, flakes made of these materials are present. The average size of the flakes is approximately 19.8 mm in length (s.d. = 6.29 mm) and 17.47 mm in width (s.d. = 6.2 mm). In the earlier phases, a larger average size is observed, which corresponds to the greater dimensions of quartzite flakes. These blanks measure, on average, 23.74 mm in length (s.d. = 7.49 mm) and 22.1 mm in width (s.d. = 7.96 mm). (Supplementary file 5).

Despite the diversity of flake production methods, centripetal and discoid schemes are notably absent. However, although most flakes result from unipolar or convergent extractions, some evidence of crossed and centripetal extractions suggests that such cores may have been present at some stage in the sequence. A small number of flakes exhibit characteristics indicative of bipolar or posed knapping, such as splinters in the percussion area, bipolar negatives on the opposite side, and sinuous lateral fragments (Fig. 7: 8).
<figure><img src="image_17.png" /><figcaption>**Fig. 4** Archaeological lithic pieces: A Typical spiculite texture of Pendueles chert (xpl). B Spherical radiolaria (green arrows) in an Alba radiolarite (ppl). C and D) End of a piece of radiolarite from</figcaption></figure>

<caption>Alba with joint extinction of phyllosilicates (45°) (xpl). E and F) Globigerinids (green arrows) characteristic of Tercis flint</caption>

Moreover, quartzite flakes with a lateral cortical side are frequent, especially in the early phase.

Mixed operational schemes combining flake and laminar blank production have been identified. These likely result from diachronic knapping processes (initially producing blades or bladelets, followed by flakes) or from the use of similar methods to obtain both blank types from a single core. Some cores are exhausted with numerous extractions and late-stage modifications, making it difficult to obtain clear technical information. In some cases, the small size of these cores and the persistence of extraction without clear

objectives suggest they may have been used for learning or practice purposes.

Across all phases, maintenance products such as core flanks, partial core tablets, and core edges are present (Table 3). Core flanks are predominantly associated with laminar methods and serve to maintain the *cintrage* and resharpen the flaking surface, whether due to knapping accidents or the absence of an optimal *carène* (Fig. 7:7). Notably, maintenance products in the pre- and post- 8.2 ka phases are mostly derived from local raw materials, whereas during the 8.2 ka event, the opposite occurs, with 70% being

<figure><img src="image_18.png" /></figure>
<figure><img src="image_19.png" /><figcaption>**Fig. 5** Different varieties of raw materials ordered by chronological phases. All percentages are in Supplementary file 1</figcaption></figure>
<table><caption>**Table 2** Number of items associated with the initial phases of the chaînes opératoires, arranged by raw materials and chronological periods</caption><thead><tr><th></th><th></th><th>Quartzite</th><th>Quartz</th><th>Alba</th><th>Pendueles</th><th>Mt. Picota</th><th>Piloña</th><th>Indeter</th></tr></thead><tbody><tr><td rowspan="3">Block/Pebble</td><td>Pre 8.2 ka event</td><td></td><td>2</td><td></td><td></td><td></td><td></td><td>2</td></tr><tr><td>8.2 ka event</td><td>2</td><td></td><td>2</td><td></td><td></td><td></td><td>4</td></tr><tr><td>Post 8.2 ka event</td><td>4</td><td>1</td><td>4</td><td>1</td><td></td><td></td><td>10</td></tr><tr><td rowspan="3">Cortical/first order flake</td><td>Pre 8.2 ka event</td><td>6</td><td></td><td></td><td></td><td></td><td></td><td>6</td></tr><tr><td>8.2 ka event</td><td></td><td></td><td>2</td><td></td><td>1</td><td>2</td><td>6</td></tr><tr><td>Post 8.2 ka event</td><td>2</td><td>4</td><td>6</td><td></td><td></td><td></td><td>12</td></tr><tr><td></td><td></td><td>14</td><td>7</td><td>14</td><td>1</td><td>1</td><td>2</td><td>40</td></tr></tbody></table>

<table><caption>**Table 3** Origin and type of cores and by-products organized by chronological phases</caption><thead><tr><th rowspan="2"></th><th colspan="3">Pre 8.2 ka event</th><th colspan="3">8.2 ka event</th><th colspan="3">Post 8.2 ka event</th><th rowspan="2">Total</th><th rowspan="2">Target</th></tr><tr><th>Local</th><th>Non-local</th><th>IT</th><th>Local</th><th>Non-local</th><th>IT</th><th>Local</th><th>Non-local</th><th>IT</th></tr></thead><tbody><tr><td>Prismatic core</td><td>1</td><td></td><td></td><td>1</td><td></td><td></td><td>3</td><td></td><td></td><td>5</td><td>Blade/bladelet</td></tr><tr><td>Pyramidal core</td><td></td><td></td><td></td><td></td><td></td><td></td><td>4</td><td></td><td></td><td>4</td><td>Blade/bladelet</td></tr><tr><td>Wide-surface core</td><td></td><td></td><td></td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td>2</td><td>Flakes</td></tr><tr><td>Flake-core</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td></td><td>1</td><td>Flakes</td></tr><tr><td>Multipolar core</td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td></td><td>1</td><td>Flakes</td></tr><tr><td>Bipolar core</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td></td><td>2</td><td>Blade/bladelet + flakes</td></tr><tr><td>Core fragment</td><td>1</td><td></td><td>1</td><td></td><td></td><td></td><td>4</td><td></td><td>3</td><td>9</td><td>Blade/bladelet + flakes</td></tr><tr><td><strong>Total</strong></td><td><strong>4</strong></td><td><strong>0</strong></td><td><strong>1</strong></td><td><strong>1</strong></td><td><strong>1</strong></td><td><strong>0</strong></td><td><strong>12</strong></td><td><strong>0</strong></td><td><strong>5</strong></td><td><strong>24</strong></td><td></td></tr><tr><td>Core flanks</td><td>1</td><td></td><td></td><td>2</td><td>4</td><td></td><td>5</td><td></td><td></td><td>12</td><td></td></tr><tr><td>Tablets</td><td></td><td></td><td></td><td>1</td><td></td><td>2</td><td>1</td><td></td><td></td><td>4</td><td></td></tr><tr><td>Edges</td><td>1</td><td>1</td><td></td><td>1</td><td>2</td><td></td><td>1</td><td>1</td><td>4</td><td>20</td><td></td></tr><tr><td><strong>Total</strong></td><td><strong>2</strong></td><td><strong>1</strong></td><td><strong>0</strong></td><td><strong>3</strong></td><td><strong>7</strong></td><td><strong>3</strong></td><td><strong>15</strong></td><td><strong>1</strong></td><td><strong>4</strong></td><td><strong>36</strong></td><td></td></tr></tbody></table>

allochthonous. Finally, a small set of crested pieces has been identified (Fig. 7:9), primarily associated with the configuration or preparation of laminar cores. These pieces highlight a greater reliance on non-local resources during the 8.2 ka event.

## Retouched pieces

A total of 64 retouched artefacts were identified, with significant differences in distribution across stratigraphic units and phases. The pre-8.2 ka phase has yielded only five tools (1.4% of the total), rising to 18 (7.4%) during the 8.2 ka phase and 41 (3%) in the post-8.2 ka phase (Fig. 9 and Supplementary file 6). Considering the variability detected in the retouched products, the following section has been divided into three chronological phases.

## Pre 8.2 ka event phase

Only five implements have been documented in the oldest phase, most of them from SU 107 and only one from SU 122, which is at the base of the shell midden. There is a burin on a cortical quartzite flake, a microburin bladelet of Pendueles chert, a notch on Flysch flint and two flint artefacts (a backed bladelet and a trapezoid on flint). It is worth noting the scarcity of retouched pieces in quartzite, considering the predominance of this raw material in this phase. The trapezoid, the only implement from SU 122, displays a short length and abrupt retouch and could correspond to a transverse arrowhead ('tranchet') (Fig. 10B/31), resembling Early Geometric Mesolithic forms typical of the Ebro Valley (the so called 'achaparradas' forms, i.e., squat or short and broad geometries) (Utrilla et al. 2009).
<figure><img src="image_20.png" /><figcaption>Fig. 6 Main operational schemes identified at El Mazo</figcaption></figure>
## Laminar blanks

### Post 8.2 ka event

<figure><img src="image_21.png" /></figure>

<figure><img src="image_22.png" /></figure>

8.2 ka e.

Pre 8.2 ka e.

<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>

## By-products

### Post 8.2 ka event

<figure><img src="image_25.png" /><figcaption>**Fig. 7** Laminar blanks (blades and bladelets) and by-products grouped by chronological phases</figcaption></figure>

### The 8.2 ka event phase

This phase is represented by 18 artefacts, predominantly made from Alba radiolarite (local) and Flysch flint (tracer). Other regional materials are less common, with only two objects each.

The typological groups are dominated by notches/denticulates and backed points/bladelets. Notable examples include four backed points, two with basal tangs or notches (Fig. 10B/20–21; 24–26), and two small trapezoids made of regional/tracer flints. Additional tools include two microburins (Fig. 10B/22–23), a borer, a piece with continuous retouch, and a diverse implement (sensu Fortea’s typological group).

### Post 8.2 ka event phase

This phase has the highest number of retouched artefacts (3% of the total assemblage), with local raw materials dominating. Typologically, geometrics predominate, with 15 specimens, including triangles (Fig. 10A/1–7; 9–10; 12; 15), trapezoids with one or two concave sides (Fig. 10A/11; 17–18), and a crescent (Fig. 10A/13). Retouch techniques include eight abrupt and seven double bevel geometrics. This is a significant change from the previous stratigraphic units. Among the backed implements, there is a blade and three bladelets: two pointed ones and a proximal fragment of a basal notch (Fig. 10A/8; 14; 16; 19). The last one (from SU 103) resembles the type described in the previous phase (SU 105). Other groups include scrapers, borers, notches/denticulates, truncations, and a ‘diverse’ (possibly fractured or unfinished geometric).

## Discussion

### Raw material supply

The acquisition of lithic resources by the human groups inhabiting El Mazo during the stratigraphic sequence reveals two discernible trends (Fig. 5 and Supplementary file 1). Before and after the 8.2 ka event, local materials accounted for over 95% of the lithic assemblage. In the earlier phase, quartzite dominated (52.7%), with quartz as the second most used material (16.7%). In contrast, after the 8.2 ka event, Alba radiolarite became the most utilised resource (34.2%), while quartzite usage declined to fourth place (4.7%), surpassed by Pendueles chert (13%) and quartz (12.7%). These changes in resource use, despite the continuous availability of local materials, seem to reflect cultural shifts. The significant transformation in raw
<figure><img src="image_26.png" /><figcaption>**Fig. 8** Width of laminar blanks (blade/bladelets) organized by chronological phases. Fragmented blanks that have retained their original width are included</figcaption></figure>

<figure><img src="image_27.png" /><figcaption>**Fig. 9** Typological groups (Fortea's typology, 1973) of the retouched industry organized by chronological phases (Pre 8.2 ka event = 4/8.2 ka event = 17/Post 8.2 ka event = 41). Symbology: R-Endscrapers,</figcaption></figure>

P-Borers, B-Burins, LBA-Backed flakes/blades, MD-Notches, FR-Truncations, D-Diverse, Lba-Backed bladelets, G-Geometrics, M-Microburins

material procurement patterns around the onset of the 8.2 ka event may be linked to reduced familiarity with local resources. This is particularly evident in the case of quartz, whose acquisition requires a profound knowledge of the area (Lombera-Hermida and Rodríguez-Rellán 2022) due to its scarcity and mode of outcropping. Although quartzite is ubiquitous in the region, its lower presence may indicate a preference for other materials.

Non-local materials constitute a small but significant portion in both phases before and after the 8.2 ka event, comprising 2.9–3.0% of the total. Half of these materials

are supra-regional, primarily Flysch flint from the eastern Cantabrian coast (1.3–1.4%). While the percentage of non-local materials remains consistent, their variety increases after the 8.2 ka event.

During the 8.2 ka event, the use of local raw material declined to 53.5%, with Alba radiolarite (21.4%) and quartzite (11.9%) indicating a “transitional” pattern. A greater diversity of raw materials emerged, including flint from western and southwestern sources (e.g., Piedramuelle, Fito) and increased eastern flint use (5.8% of Flysch flint). Additionally, Tercis flint, a French material from the
<figure><img src="image_28.png" /></figure>

<figure><img src="image_29.png" /><figcaption>**Fig. 10** Microlithic armatures (geometrics + backed pieces) and microburins ordered chronologically and by raw material (Retouch: ab.: abrupt; d.b.: double bevel; s.i.: simple inverse). P. (provenance): L. (local); R. (regional); T. (tracer); -(Indeterminate)</figcaption></figure>
Adour River terraces, appears for the first time, signifying broad geographical reach despite its scarcity.

The origin of the flint, in general terms, points towards both the east and the west of the Cantabrian Region. The Cantabrian coastal plain appears to serve as a crucial communication route that spans the entire northern coast, encompassing Atlantic France (Tercis flint). However, potential lithic resources from western Iberia remain undefined, limiting visibility of contacts in that direction. Materials from the interior mountains (e.g., Piloña flint, Piedramuelle flint, Fito chert, Portillas chert) have been identified within a distant-local or regional radius (SW-SE), likely transported via river basins near the coast. Notably, a piece of Portillas chert with primary cortex confirms direct access to outcrops in the Picos de Europa, possibly along the Deva and Cares Rivers (Fig. 1).

## Chaînes opératoires integrity

The integrity of the *chaînes opératoires* at El Mazo is difficult to assess due to the limited number of remains recorded in each stratigraphic unit (SU) (Table 1), the diversity of raw materials, and the reduced excavated area (Fig. 1). In a previous work, we proposed a classification of the lithic series into three categories based on the integrity of the *chaîne opératoire*: complete, incomplete and broken (Herrero-Alonso et al. 2020).

Generally, the closest local materials (< 15 km) usually appear in a complete chain, the extra-regional ones are broken, and the regional ones may be incomplete or broken (Table 4 and Supplementary file 7). However, this pattern is not always observed at El Mazo. Radiolarite and quartzite are the only local materials displaying a complete *chaîne opératoire*

<table><caption>**Table 4** Integrity of chaînes opératoires separated by raw materials and organized by chronological phases</caption><thead><tr><th></th><th></th><th>Pre 8.2 ka event</th><th>8.2 ka event</th><th>Post 8.2 ka event</th></tr></thead><tbody><tr><td rowspan="5">Local</td><td>Alba radiolarite</td><td><strong>Complete</strong></td><td><strong>Complete</strong></td><td><strong>Complete</strong></td></tr><tr><td>Pendueles chert</td><td><em>Broken</em></td><td>Incomplete</td><td><strong>Complete</strong></td></tr><tr><td>Portillas chert</td><td>Incomplete</td><td>Incomplete</td><td>Incomplete</td></tr><tr><td>Quartzite</td><td><strong>Complete</strong></td><td><strong>Complete</strong></td><td><strong>Complete</strong></td></tr><tr><td>Quartz</td><td><strong>Complete</strong></td><td><em>Broken</em></td><td><strong>Complete</strong></td></tr><tr><td rowspan="5">Regional</td><td>Piloña flint</td><td><em>Broken</em></td><td>Incomplete</td><td><em>Broken</em></td></tr><tr><td>Piedramuelle flint</td><td>-</td><td><em>Broken</em></td><td>-</td></tr><tr><td>Urgonian flint</td><td>-</td><td><em>Broken</em></td><td><em>Broken</em></td></tr><tr><td>Monte Picota flint</td><td><em>Broken</em></td><td>Incomplete</td><td><em>Broken</em></td></tr><tr><td>Fito chert</td><td>-</td><td><em>Broken</em></td><td><em>Broken</em></td></tr><tr><td rowspan="2">Tracer</td><td>Flysch flint</td><td><em>Broken</em></td><td>Incomplete</td><td><em>Broken</em></td></tr><tr><td>Tercis flint</td><td>-</td><td><em>Broken</em></td><td>-</td></tr></tbody></table>

throughout all phases, while quartz and Pendueles chert exhibit complete *chaînes* only in specific phases, suggesting cultural shifts in the management of local lithologies, as previously noted.

Distant local materials, such as Portillas chert, appear incomplete, represented by by-products and preparation flakes but lacking cores. In this case, the segmentation of the knapping sequence and the low frequency of this variety are directly linked to its moderate distance from the source. However, its presence reflects detailed familiarity with the eastern area near the site, particularly during the 8.2 ka event, when its frequency equals or even surpasses that of closer raw materials.

For regional and tracer materials, *chaînes opératoires* are consistently broken before and after the 8.2 ka event, represented mainly by final blanks and tools, with few remains overall. However, during the 8.2 ka event, some regional and tracer materials are found in incomplete form, including not only final blanks and retouched pieces but also by-products, suggesting on-site knapping activities and the possible introduction of prepared cores, although no cores have been identified.

Knapping objectives include flakes, blades and bladelets, with raw material usage varying. Quartzite was almost exclusively used for flake production, quartz was employed for both flakes and bladelets, and chert/flint was used for flakes, blades, and bladelets. The resulting blanks are generally small, with flakes being more frequent in lower stratigraphic units due to the greater exploitation of quartzite. Knapping schemes remained consistent throughout the sequence, showing no significant changes across the different phases. Unipolar and convergent prismatic schemes were employed for blade production in all phases, while unipolar or multipolar methods were used for flake production. Bipolar knapping and flake-cores were occasionally identified, but no centripetal or discoidal flake production methods were observed. Cores were intensively exploited, often to exhaustion, with natural ridges and crest/semi-crest preparations used in early stages.

The blanks selected for the retouching phase are primarily blades and bladelets, accounting for nearly half of the total assemblage, followed by flakes. In addition to these target blanks, other pieces have been identified, such as by-products (crests, edges) and cortical flakes, with a notable increase in these during the 8.2 ka event. Furthermore, many of these blanks are made from regional or tracer raw materials, likely reflecting a more intensive use of available resources. Additionally, during this event, a burin spall made of Flysch flint was identified, indicating evidence of tool maintenance and repair processes.
Mobility and raw material management

The mobility of prehistoric groups during the Asturian
period has usually been classified as reduced, based on pat-
terns such as the preference for quartzite and less frequent
acquisition of high-quality flint, often replaced by local vari-
eties (González Morales et al. 2004; Terradas et al. 2007;
Arias et al. 2009; Marín-Arroyo et al. 2020).

However, a detailed analysis of quartzite and flint usage
across Cantabrian Palaeolithic and Mesolithic sites reveals
less pronounced distinctions. Asturian deposits typically
exhibit high quartzite percentages, ranging from 61%– 88%
(Arias Cabal 1991). This elevated quartzite proportion
 extends to earlier in the Pleistocene, as it has been identi-
fied in the Mousterian, Aurignacian, and Solutrean periods,
where it exceeds 50% (Herrero-Alonso 2018). However, the
percentage of quartzite in this area is indeed very high when
compared to sites in other geographical areas, previously
noted by Fernández Tresguerres (Fernández Tresguerres
2004, 2006). At El Mazo, quartzite usage declines over time,
starting at 53.3% (pre- 8.2 ka event) and dropping to 4.6%
(post- 8.2 ka event). Therefore, the quartzite occurrence
might be linked to the utilisation of the prevalent lithological
base in the Cantabrian Coast region, where this raw material
is abundant. Nevertheless, it is crucial to consider that raw
material selection is influenced by factors such as availabil-
ity, the nature and size of the initial nodule, raw material
characteristics, and cultural preferences.

Regarding the second pattern, local chert/radiolarite vari-
eties tend to dominate, but this does not necessarily mean
the abandonment of more distant flint varieties, as observed
in El Mazo. The percentage of these non-local materials in
the pre- and post- 8.2 ka event phases is reduced (3.0–4.2%
respectively of all identified materials), although some varie-
ties come from more than 100 km away. These percentages
are relatively similar to those at the Mesolithic site of La
Uña (León) (L.III: 4.9%/L.IV: 5.2%), where long-distance
supply is also detected (Herrero-Alonso et al. 2021a). Even
at El Espertín, where the percentage of non-local flint is
minimal (0.2%), these distant flints are detected (Herrero-
Alonso et al. 2020). Therefore, based on the available
data, it appears that resource procurement in Asturian and
Mesolithic sites was not exclusively limited to the local
environment.

In addition to the Asturian coastal occupations, which
primarily involve resource collection along the east–west
axis of the Cantabrian coastal plain, there are Holocene sites
in inland areas associated with mountain environments in
the Cantabrian Region. Notable sites on the northern slope
include Los Canes (Arias Cabal et al. 1981; Arias Cabal
and Pérez Suárez 1990, 1992, 1995) and Arangas (Arias
Cabal and Pérez Suárez 1995; Arias Cabal et al. 2013) in the
Cares Valley, while higher altitudes in the Picos de Europa

region feature sites like La Calvera (Díez Castillo 1996) and
La Mina (Herrero Ortuño and Vega Gómez 1990) (Fig. 1).
On the southern slope, in the north of the province of León,
there are sites such as La Uña (Neira-Campos et al. 2012),
El Espertín (Neira Campos and Fuertes Prieto 2009), and La
Braña/Arintero (Vidal Encinas and Prada Marcos 2010). The
use of those caves, especially linked to higher altitude areas,
was possible mainly after the end of the Last Glacial thanks
to the retreat of the glaciers. In fact, most of the sites on
the southern slope, considered seasonal occupations during
warmer times of the year, all of them close to the mountain
passes that connect north and south, are dated after the 8.2
ka event (Fuertes-Prieto et al. 2023). La Uña and El Espertín
demonstrate mobility within regional areas, with lithic mate-
rials including flint from Cantabrian coastal sources (e.g.,
Pendueles, Monte Picota) and a significant percentage of
Flysch flint. Interestingly, sites like La Uña and El Espertín
contain flints from the upper Ebro basin, absent at El Mazo.

Evaluating the mobility of Mesolithic groups as regards
resource supply, territorial occupation strategies, and inter-
actions with neighbouring groups presents a complex chal-
lenge. A crucial aspect to consider is whether these groups
engaged in direct exploitation or indirect acquisition of
resources (through exchanges and, therefore, social con-
tacts). Prehistoric groups likely directly accessed abundant
and nearby local resources, transporting nodules to the site
and developing the entire knapping sequence there. How-
ever, even in the closest materials, there may be segmenta-
tion in the *chaînes opératoires*, so that the first phase may be
absent, and could have taken place in the location where the
nodules were collected or even in other unexcavated areas
of the site. With this premise in mind, and excluding quartz,
all the local materials identified at El Mazo (< 30 km) could
have undergone direct exploitation, exhibiting either com-
plete or incomplete *chaînes opératoires* (Fig. 11).

In the case of broken chains, represented by a few remains
(final blanks or retouched pieces), it is plausible to consider
the possibility of acquisition through exchange, without
ruling out direct exploitation at certain points along the
mobility routes and territorial occupation of these groups.
However, even raw materials that are from nearby-local
sources may suffer from limited availability due to techni-
cal or cultural reasons, such as scarcity or environmental
conditions. The restricted and sporadic use of quartz, which
is classified as a local raw material, may be attributed to its
limited availability in the environment and distinctive tech-
nical management. This includes knapping schemes such
as bipolar, which makes it difficult to identify characteristic
pieces found in other schemes.

Upon analysing the acquisition and management of mate-
rials, two discernible patterns emerge. In the phases before
and after the 8.2 ka event, all non-local varieties have broken
chains. However, in the 8.2 ka event phase there are regional

<figure><img src="image_30.png" /></figure>
<figure><img src="image_31.png" /><figcaption>**Fig. 11** Dispersion map of the lithic raw materials identified at El Mazo divided into chronological phases. The rectangles indicate the degree of integrity of the chaînes opératoires</figcaption></figure>
flints and even tracers that have an incomplete chain, there-
fore raising the possibility of direct exploitation of the raw
materials. Among them, Flysch stands out, as it is a tracer
flint that can be exploited on the coast and that, despite its
distance (130 km), is more abundant than other flint that
outcrops on closer coastlines, such as Monte Picota or Urgo-
nian. Therefore, during this phase, El Mazo received more
materials from distant areas, particularly from coastal out-
crops located to the east and from the Landes. Many of those
materials are in a state of exploitation that is more closely
linked to their catchment area, giving the impression of
greater mobility of both the objects and the groups involved.

Perhaps the significant change in terms of the occupa-
tion model could respond to a modification in the use of the
site, with more punctual occupations within longer routes
throughout the entire Cantabrian region. Considering that
human groups would carry a lithic kit with them during their
travels if they came from more distant places, some of these
discarded raw materials would be non-local.

At El Mazo, a decrease in summer seawater temperatures
during the 8.2 ka event has been identified by analysis of
stable oxygen isotopes in shells (García-Escárzaga et al.
2022b). In addition, an increase in the exploitation of mala-
cological resources has been detected, perhaps associated
with a population increase in this area.

In this sense, in recent years, palaeodemographic studies
based on “summed probability distributions” (SPD) dating
series (time series and bootstrap simulations) have elabo-
rated models in which a population increase is observed in
the first part of the Holocene in the Cantabrian area, whose
beginning fluctuates between 8500 cal BP (Fernández-López
de Pablo et al. 2019), 8200–7400 cal BP (Clark and Barton
2022) or ca. 8075 cal BP (González Rabanal 2022).

These population dynamics could be related to the genetic
flows evidenced in DNA analyses. In this sense, the data on
Mesolithic individuals from Iberia correspond to the lin-
eages characteristic of Western European Epipaleolithic/
Mesolithic groups (WHG), although there is a greater per-
sistence of the Upper Palaeolithic heritage in the Iberian
context. From 8000 cal BP, there is evidence of genetic
contributions from Eastern Europe (EHG) to Central and
Western European regions (and vice versa), which seems
to indicate greater mobility among the different Mesolithic
groups (Posth et al. 2023). In fact, the oldest evidence of
this genetic influence in northern Iberia from southeastern
Europe (the Balkans), dated to around 8200 cal BP, has been
found at the Mazo site (Allentoft et al. 2024).

In other peninsular areas, the influence of the climatic
change of the 8.2 ka event has been related to group migra-
tions, including demographic gaps in the Lower Ebro Val-
ley (Utrilla et al. 2009). Notably, in the Upper Ebro Valley
and the Basque Country, there is evidence of trans-Pyre-
nian influences (Alday Ruiz and Cava Almuzara 2009; Soto

et al. 2016) that may be related to both mobility and more
dynamic social interactions. In El Mazo, there are no raw
materials from the Ebro valley, but there are some from the
trans-Pyrenean area, as well as other remains linked more
to this second geographic area (Fig. 11). Given the consist-
ent presence of flint originating from the Cantabrian coast,
the coastal route connecting this region with southwest-
ern France appears to have been a crucial communication
corridor.

## Typology in the context of the Mesolithic

The typological analysis reveals a diachronic change
throughout the stratigraphic sequence studied, particularly
in the microlithic armatures (backed bladelets and
geometrics) (Table 5). These transformations can be linked
to regional events that occurred for approximately 1000
years, around 8500–7400 cal BP. During this period, the
Final Mesolithic or Geometric Mesolithic developed in
Iberia (Utrilla et al. 2009), corresponding to the European
Second Mesolithic at a continental level, which is
characterised by the diffusion of blade/bladelets and trapeze
industries (Marchand and Perrin 2017). In the Cantabrian
region, the Mesolithic of this phase is typically associated
with the Asturian tradition, with few occurrences (or near
absence) of geometrics. However, this perspective has been
nuanced in recent decades (Arias Cabal and Fano 2009;
Arias et al. 2021). A "Mesolithic with geometrics" has been
proposed in a general sense for this region, given that the
percentage of these typological forms (< 5%) remains lower
than in other Iberian areas (Neira-Campos et al. 2016). This
peculiarity extends to the northwest (Ramil Rego et al.
2021; Fuertes-Prieto et al. 2023).

The microlithic armatures at El Mazo exhibit significant
chronological differences, especially before and after 8000
cal BP (Fig. 10 and Table 4). The first stage, spanning the
initial occupation of the rock-shelter until 8000 cal BP (ca.
second half of 9th millennium cal. BP), is characterised by
a significant proportion of microlithic armatures, including
both backed pieces (points) and geometrics. These pieces,
exclusively trapezoids with abrupt retouching, are linked to
the microburin technique. This pattern aligns with the diffu-
sion of trapezoid industries characteristic of the Late Meso-
lithic in Iberia, a process initiated around 8500–8400 cal
BP in the eastern peninsula (Gómez-Puche and Fernández-
López de Pablo 2024).

Backed bladelets in this stage are predominantly curved
points, with three notable examples featuring basal tangs
manufactured from distant local and undeterminable
regional flints (Fig. 10/16; 25–26). This type is rare in the
Cantabrian region but has parallels at Aizpea, in the western
Pyrenees (Cava 2001) and has been linked to similar forms
in continental and British contexts (Lawrence et al. 2022).

<figure><img src="image_32.png" /></figure>
<table><caption>**Table 5** Armatures (geometric and backed bladelets), grouped into two absolute chronological phases according to their provenance from stratigraphic units and test pits</caption><thead><tr><th rowspan="3"></th><th rowspan="3"></th><th colspan="2">Pre 8.2 ka event</th><th colspan="2">8.2 ka event</th><th colspan="4">Post 8.2 ka event</th></tr><tr><th colspan="2">~ 2nd half 9th mil. Cal. BP</th><th colspan="4">~ 1st half 8th mil. Cal. BP</th></tr><tr><th>122</th><th>107</th><th>105</th><th>113,<br>120</th><th>103,<br>106</th><th>100,<br>101</th><th>101D</th><th>3</th><th>803</th></tr><tr><th>Segment</th><th></th><th colspan="2">Inner</th><th colspan="2"></th><th colspan="2">Outer</th><th colspan="2">North</th></tr></thead><tbody><tr><td rowspan="3">Triangle</td><td>Simple ret</td><td></td><td></td><td></td><td></td><td>1</td><td></td><td></td><td>1</td></tr><tr><td>Double bevel ret</td><td></td><td></td><td></td><td></td><td>1</td><td></td><td>4</td><td>1</td><td>6</td></tr><tr><td>Abrupt ret</td><td></td><td></td><td></td><td></td><td>1</td><td>1</td><td>2</td><td>1</td><td>5</td></tr><tr><td rowspan="3">Trapeze</td><td>Transverse arrow-<br>head/Abrupt ret</td><td>1</td><td></td><td></td><td></td><td></td><td></td><td></td><td>1</td><td>6</td></tr><tr><td>Abrupt ret</td><td></td><td>2</td><td></td><td>2</td><td></td><td></td><td></td><td>1</td><td>5</td></tr><tr><td>Basal notch</td><td></td><td>2</td><td></td><td>1</td><td></td><td></td><td></td><td></td><td>3</td><td>6</td></tr><tr><td rowspan="2">Backed point</td><td>Convex</td><td></td><td>1</td><td>1</td><td></td><td></td><td></td><td>1</td><td></td><td>3</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>4</td></tr><tr><td>Backed bladelet/flake</td><td></td><td>1</td><td>1</td><td>5</td><td>2</td><td>4</td><td>4</td><td>1</td><td>8</td><td>29</td></tr></tbody></table>

The second stage, dated 8000 cal BP onwards (ca. first half of 8th millennium cal BP), was documented in the outer and northern pits as well as in the upper sequence of the inner area. During this phase, points with basal tangs are absent, but new typological forms appear, including triangles (the most prevalent type) and a single crescent. Triangles exhibit a new type of retouch: the double bevel. Geometrics become more numerous outside the shelter, crafted from both local materials (radiolarite, quartzite) and tracer flints (Flysch), with the latter concentrated in the northern area (SU 803). The abundance of geometrics in this phase is significant (Table 5), with percentages comparable to the Geometric Mesolithic in other Iberian regions, though the limited number of retouched pieces in each SU constrains further analysis.

The sequence at El Mazo highlights a shift from a dominance of trapezoids before 8000 cal BP to an increased presence of triangles in later periods. This pattern mirrors the evolution of the Geometric Mesolithic in other Iberian areas, such as the Ebro Valley and Levante (Alday Ruiz and Cava Almuzara 2009; Martí Oliver et al. 2009; Utrilla et al. 2009; Soto et al. 2023). Comparable types, such as backed basal points, are documented in the western Pyrenees (Aizpea) (Cava 2001) while the so-called "triángulos oclusos" (that is, triangles with the smaller retouched edge oriented in the same direction as the larger one) are reported in the Upper Ebro Valley (Fig. 10–6) (Alday Ruiz and Cava Almuzara 2009). Although the “double bevel” is associated with Neolithic contexts in some areas, in the interior of the Cantabrian region and northwest areas of Iberia (Galicia) it appears in Mesolithic levels dated in the 8th millennium cal BP (Ramil Rego et al. 2021; Fuertes-Prieto et al. 2023). At El Mazo, the oldest appearance of this retouch can be dated to around 7700–7600 cal BP, in a well dated Mesolithic

context (SU 3: UGAMS- 5407, 6790 ±30 BP, 7727–7638 cal BP). A similar example is documented in burial structure II at Los Canes (Fig. 1), dated to the first half of the 8th millennium cal BP (Arias Cabal and Fano 2009).

## Conclusions

The lithic industry at El Mazo reveals distinct patterns in raw material management and armature production throughout the stratigraphic sequence, reflecting cultural shifts over time. The procurement strategy combined both local and non-local materials, with some sources located tens of kilometres away, particularly during the 8.2 ka event. These patterns suggest regional mobility and exchange networks operating on a larger scale than previously assumed.

Following prior studies on the site's stratigraphic sequence, the division into three phases used in this work has been largely validated, particularly regarding raw material exploitation. However, no major changes in knapping techniques were observed, except for variations linked to the predominant raw materials. Two main production objectives are identified: flakes, which dominate the pre- 8.2 ka phase due to the prevalence of quartzite, and blades/microlaminar blanks, which are consistently produced throughout the sequence using prismatic and pyramidal cores with single percussion platforms.

From a typological perspective, the evolution of micro-lith types follows broader Iberian and European trends, especially the spread of trapezoidal industries characteristic of the Second or Final Mesolithic (from ~8500 cal BP). However, not all technological ‘innovations’ of this
period, such as pressure or indirect percussion, are well represented at El Mazo, as is also the case at other Mesolithic sites in Iberia. Nevertheless, its sequence provides additional insight into cultural transformations and allows for a more precise understanding of the duration of the three proposed phases.

The technological and typological characteristics observed at El Mazo challenge traditional interpretations of Asturian culture, revealing significant cultural shifts between approximately 8500 and 7500 cal. BP. While the pre-8.2 ka phase partially aligns with the classical model (Asturian) -mainly due to the dominance of quartzite-, technological and typological evidence indicates notable divergences, linking this site to broader Iberian dynamics and highlighting the adaptability of these prehistoric groups.

Stratigraphic units associated with the 8.2 ka event show clear changes in raw material procurement and typological features, suggesting a cultural shift. There is a marked decline in the use of quartzite and quartz—the previous dominant lithologies- and an increase in both the quantity and diversity of non-local raw materials, some sourced from significantly distant areas. These extra-local materials appear in the form of cores introduced during production phases, including cortical blanks and by-products. Additionally, this phase sees a higher percentage of microlithic armatures, particularly with the introduction of a new type of backed point: the basal notched point.

These changes in lithic resource management, the inclusion of distant raw materials within productive chaînes opératoires, and the introduction of new armature types suggest intensified mobility and expanded long-distance contacts. This pattern aligns with broader European dynamics, as corroborated by recent genetic studies (Allentoft et al. 2024). Furthermore, these transformations appear closely tied to the climatic deterioration of the 8.2 ka event, which likely influenced subsistence strategies (García-Escárzaga et al. 2022b), raw material exploitation, and territorial organization. Population interactions, particularly along the eastern Cantabrian coast and into southwestern France, may have further shaped these changes, potentially influenced by genetic influx from the east.

This cultural pattern associated with the 8.2 ka phase persisted in the sequence at El Mazo for a few decades beyond the established chronological limit for this phase (8300–8075 cal. BP), lasting until approximately 8000 cal. BP. After this threshold, new cultural shifts are evident, including a narrowing of raw material procurement sources and the introduction of new geometric microlith types, such as triangles with double bevel retouch and segments.

In conclusion, the lithic industry at El Mazo highlights the complexity, adaptability, and dynamic interactions of Mesolithic groups in the Asturian region. These findings challenge previous notions of restricted mobility and

emphasize the role of environmental and cultural factors in shaping prehistoric subsistence and technological strategies.

**Supplementary Information** The online version contains supplementary material available at https://doi.org/10.1007/s12520-025-02225-3.

**Acknowledgements** This research was performed as part of the projects HAR2010-22115-C02-01, HAR2013-46802-P, HAR2016-75605-R, funded by the Spanish Ministry of Economy and Competitiveness, and PID2021-124589 NA-I00 and PID2020-118359GB-I00, funded by the funded by MICIU/AEI. DHA has received funding from the postdoctoral fellowship program of Xunta de Galicia (Consellería de Cultura, Educación, Formación Profesional y Universidades). AGE is currently working in the framework of a Marie Skłodowska Curie – Postdoctoral Fellowship (HEU-101064225-NEARCOAST), funded by the European Union. DCS was funded by the Ramón y Cajal program, (grant RYC2022-036585-I) (Ministerio de Ciencia e Innovación, Spain). We would like to thank the reviewers for their valuable comments, which have significantly improved this work. Funding for open access charge: Universidade de Vigo.

**Author contribution** The study of the lithic industry was carried out by DHA and NFP. The textural description of the different raw materials was carried out by AT. Interpretation of the results was carried out by DHA, NFP, DCS and IGZ. The text was drafted by DHA and NFP. The text was reviewed, improved and edited by AT, DCS, AGE, JCG and IGZ. The figures were designed by DHA, NFP and JCG.

**Funding** Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

**Data availability** No datasets were generated or analysed during the current study.

## Declarations

**Competing interests** The authors declare no competing interests.

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