Sedimentological and geochemical analyses of VC08 revealed five distinct units (Units V to I, from bottom to top; Figure 3) corresponding to the last four historical climate periods and/or transitions up to Recent times (Moreno et al., 2012): RHIP, DA, MCA, and LIA (Figures 2A, 3).

The lowermost Unit V (400–325 cm below sea floor, bsf) covers almost the entire RHIP (from ca. 2025 to 1504 cal yr BP, i.e., from 76 BCE to 446 CE) and likely the lower DA (Figure 3). This unit is composed of brownish light green mud and silty mud, with subtle variations of the coarse and fine fractions, showing an upward coarsening trend, with no primary sedimentary structures (Figure 3). An increase of the sand fraction is observed at the upper part of the unit (348–335 cm bsf) (Figure 3). Sediments in Unit V are poorly to very poorly sorted, and consist largely of terrigenous components, including sub-angular grains of quartz and K-feldspar, plagioclase and muscovite. Also, bioclasts, primarily benthic foraminiferal and mollusk (bivalve/gastropods) shells, as well as mottling indicative of bioturbation, were observed throughout the unit (Figures 3, 4A,B). Terrigenous elements (Si, K, Al, Ti, and Fe) display an overall upward decreasing trend up to 377 cm bsf, followed by a prominent, fluctuating upward increasing trend towards the top unit (Figure 3). In contrast, Ca exhibits an overall upward increasing trend up to 350 cm bsf, followed by a decreasing trend towards the top unit. Notably, two major fluctuations at around 349 and 336 cm bsf coincide with low values in terrigenous elements and Ca (Figure 3). Fe/Ca and Ti/Ca ratios follow similar trends than terrigenous elements. However, where terrigenous elements exhibit low values, Fe/Ca and Ti/Ca ratios show high values (Figure 3). In contrast, Br and Br/Ti ratios, as well as Mo (inc/coh) ratio display anticorrelated trends with terrigenous elements (Figure 3). Besides, Sr/Ca ratio displays no significant variability apart from notable peaks that also correlate with peaks in Fe/Ca, Ti/Ca and Br/Ti ratios (Figure 3).

Unit IV (325–265 cm bsf) spans the upper DA, including the DA-MCA transition, which occurred before ca. 1014 cal yr BP (i.e., before 934 CE; Figures 2A, 3). This unit is composed of brownish light green mud/silty mud, with a homogeneous composition of the coarse and fine fractions. Unit IV contains slightly lower sand contents than Unit V (Figure 3). Unit IV has a mottled appearance indicative of bioturbation and lacks primary sedimentary structures (Figure 3). Sediments in this unit are poorly sorted and are mainly composed of terrigenous components such as quartz and K-feldspar grains, plagioclase and mica. Bioclastic elements, including foraminiferal and mollusk shells, are also present. In contrast, this unit displays higher abundances of foraminiferal and mollusk shells than Unit V. Terrigenous elements (Si, K, Al, Ti, and Fe) and Rb/Zr, Fe/Ca, and Ti/Ca ratios, as well as Mo (inc/coh) ratio exhibit upward increasing trends with moderate to high fluctuations. In contrast, Ca, Br, and Br/Ti ratios display weak anticorrelated trends with terrigenous elements and Fe/Ca and Ti/Ca ratios. Sr/Ca ratio exhibits no significant variability, except for some subtle peaks that correlate with peaks in Fe/Ca, Ti/Ca, and Br/Ti ratios (Figure 3).

Unit III (265–140 cm bsf) spans the entire MCA, including the MCA-LIA transition, which occurred before ca. 385 cal yr BP (i.e., before 1565 CE; Figures 2A, 3). This unit consists of brownish light green mud and silty mud, characterized by a weak upward coarsening trend (Figure 3). However, a significant increase of the sand fraction was observed in the upper part of the unit from 158 to 150 cm bsf (Figure 3). Sediments within unit III are poorly sorted, composed largely of terrigenous components such as quartz, K-feldspar, plagioclase, and mica grains. Bioclastic elements, including foraminiferal and mollusk shells, are also present. Unit III also has a mottled appearance indicative of bioturbation and lacks primary sedimentary structures (Figure 3). Terrigenous elements such as Si, K, Al, Ti, and Fe display very weak upward decreasing trends with moderate fluctuations, although the values are lower than the underlying Unit IV (Figure 3). In contrast, Ca displays no significant upward variability but shows higher values than the underlying sediments (Figure 3). Likewise, Mo (inc/coh) ratio, despite exhibiting minor fluctuations, displays no significant variability (Figure 3). Fe/Ca and Ti/Ca ratios display comparable trends to terrigenous elements. However, when terrigenous elements exhibit low values, Fe/Ca and Ti/Ca ratios show correspondingly high values (Figure 3). In contrast, Br and Br/Ti ratio display anticorrelated trends with terrigenous elements (Figure 3). Besides, Sr/Ca ratio displays no significant variability apart from some peaks which also correspond to peaks in Fe/Ca, Ti/Ca, and Br/Ti ratios (Figure 3).

Unit II (140–33 cm bsf) covers the entire LIA (from ca. 385 to 114 cal yr BP, i.e., from 1565 to 1836 CE; Figures 2A, 3). Unit II, composed of brownish light green mud/silty mud, exhibits a weak fining-upward trend, with interbedded sandy intervals from 118 to 62 cm bsf (Figure 3). Unit II has a mottled appearance indicative of bioturbation and lacks primary sedimentary structures (Figures 3, 4A,B). Sediments within this unit are poorly to very poorly sorted, with a significant relationship between sorting and mean grain size. The cumulative frequency curves display a dominant bottom-up trend in suspended load deposition, but also feature interbedded fluctuations characterized by reduced suspended load and increased saltation load (Figure 5). These fluctuations coincide with peaks in elemental ratios such as Fe/Ca and Sr/Ca, but are anticorrelated with terrigenous elements (Si, K, and Ti) and elemental counts in Ca (Figures 3, 5A). Sediment composition in Unit II is similar to the underlying units, consisting largely of terrigenous components such as quartz and K-feldspar grains, plagioclase, and muscovite, as well as bioclasts including foraminiferal, bivalve, and gastropod shells (Figures 3, 4A,B). The abundance of bioclastic components, including shell fragments, is considerably higher within the interbedded sandy layers (Figures 3, 4A,B), where the cumulative frequency curves show an increased proportion of saltation loads (Figures 5A,B). Terrigenous elements (Si, K, Al, Ti, and Fe) exhibit a weak upward increasing trend, displaying higher values with larger fluctuations than the underlying Unit III up to 70 cm bsf (Figure 3). The values of terrigenous elements decrease upward to 50 cm bsf and then slightly increase towards the upper part of the unit (Figure 3). Similarly, Fe/Ca, Ti/Ca, and Sr/Ca ratios show an overall upward increasing trend up to 65 cm bsf, followed by an upward decreasing trend (Figure 3). Conversely, Br, Br/Ti and Mo (inc/coh) ratios exhibit anticorrelated trends with Fe/Ca and Ti/Ca ratios up to 65 cm bsf, where their trends align (Figure 3). In addition, elemental counts of Ca display an anticorrelated trend with Fe/Ca, Ti/Ca, and Sr/Ca (Figure 3).

The uppermost Unit I (33–0 cm bsf) spans from around 1836 CE to the time of sediment coring (Figure 2A; Cerrillo-Escoriza et al., 2024a). Unit I is composed of mud and silty mud and exhibits an upward coarsening trend (Figure 3). In addition, an increase of the sand fraction is observed in the uppermost part of the unit (20–4 cm bsf; Figure 3). Sediments are poorly to very poorly sorted and consist largely of terrigenous and bioclastic components. Terrigenous elements (Si, K, Al, Ti, and Fe) and Ca display a weak fluctuating decreasing trend up to 4 cm bsf, followed by a subtle increasing trend towards the unit top (Figure 3). A noticeable fluctuation in this decreasing trend is observed at the bottom of the unit at 30 cm bsf, coinciding with a low peak in terrigenous elements and Ca (Figure 3). Conversely, Fe/Ca and Ti/Ca ratios display no significant variability, although a high peak coinciding with the low peak in terrigenous elements and Ca is observed (Figure 3). In contrast, Br and Br/Ti ratio, and likely Mo (inc/coh) ratio, exhibit an overall upward increasing trend (Figure 3). Additionally, Sr/Ca ratio shows no significant variability except for a high peak observed at 30 cm bsf, which also corresponds to peaks in Fe/Ca, Ti/Ca, and Br/Ti ratios (Figure 3).

Sedimentological and geochemical analyses of GC26 revealed two distinct units (Unit II and Unit I, from bottom to top; Figure 6), corresponding to the last two climatic periods over the last ∼600 years. The first is the LIA from 650 to 150 cal. yr BP, and the second is the Industrial Period (IP; 150 cal yr BP–time of coring) (Figures 2B, 6).

Unit II (207–38 cm bsf) spans the entire LIA, covering at least from 454 to <100 cal. yr BP (i.e., from 1494 to <1850 CE; Figures 2B, 6). Unit II is composed of brownish green sandy/silty mud with interbedded sandy-rich intervals up to 25 cm thick (Figures 4C,D, 6). A weak fining upward trend is observed from 138 cm bsf towards the top of the unit, in agreement with clay (%) trends and Rb/Zr ratio (Figure 6). The sandy-to-silty mud sediments of Unit II are poorly to very poorly sorted, consisting predominantly of terrigenous components (Figure 6), including sub-angular grains of quartz, K-feldspar, plagioclase, and muscovite, along with bioclasts such as foraminiferal, bivalve, and gastropod shells (Figures 4C,D). These sediments exhibit a mottled appearance and the presence of burrows, indicating bioturbation, and lack primary sedimentary structures (Figures 4C,D). The interbedded sandy-rich intervals display sharp boundaries with the massive muddy sediments, with grain size gradually decreasing towards the top, forming fining-upward sequences (Figure 6). These sandy intervals exhibit sedimentary structures such as convoluted and wavy laminae. Convoluted laminae, primarily composed of fine-grained sands, often appear deforming the surrounding bioturbated, muddy sediments, exhibiting a distorted internal structure (Figures 4C,D). These intervals generally lack well-organized internal features, ripple marks are seldom observed, and wavy laminations are poorly developed or distorted (Figures 4C,D). The sandy-rich intervals also contain carbonate rock fragments and plant debris, along with minor proportions of bioclasts (Figure 4D). Terrigenous elements (Si, K, Al, Ti, and Fe) exhibit high values, interrupted by short-term fluctuations featuring lower values (Figure 6). Fe/Ca, Ti/Ca, and Sr/Ca ratios remain moderately constant up to 145 cm bsf, where they increase upward with short-term fluctuations (Figure 6). Conversely, elemental counts of Br, Br/Ti, and Mo (inc/coh) ratios exhibit anticorrelated trends with Fe/Ca and Ti/Ca ratios (Figure 6). Moreover, the elemental counts of Ca decrease from the unit bottom to 136 cm bsf, followed by moderate, nearly constant values towards the unit top (Figure 6). At the base of the sandy-rich intervals, there are notable decreases of clay (%), terrigenous elements (Si, K, Al, Ti, and Fe), Rb/Zr, Fe/Ca, Ti/Ca and Sr/Ca ratios (Figure 6). Similarly, Br, Br/Ti and Mo (inc/coh) ratios show small decreases (Figure 6). In contrast, these basal intervals are characterized by high peaks in Ca counts (Figure 6) and higher proportions of calcite (Figure 4D).

The uppermost Unit I (38–0 cm bsf) spans the most recent period, from <1980 CE to the time of sediment coring (Figure 2B; Cerrillo-Escoriza et al., 2024a). This unit, also composed of bioturbated, brownish green silty muds, shows a slight fining-upward trend above a sandy-rich basal interval (Figure 6). The sandy-rich interval is similar to those in the underlying Unit II (Figure 6) and exhibits sedimentary structures such as convoluted laminae (Figures 4C,D). These convoluted laminae, primarily composed of fine-grained sands, appears deforming the surrounding bioturbated muds, resulting in a chaotic internal structure (Figures 4C,D). Sediments are poorly to very poorly sorted and consist largely of terrigenous and bioclastic components. Terrigenous elements (Si, K, Al, Ti, and Fe) and Ca exhibit higher values than in Unit II and a nearly constant upward trend (Figure 6). Similarly, Rb/Zr, Fe/Ca, Ti/Ca, and Sr/Ca ratios have constant values (Figure 6). In contrast, Br and Br/Ti and Mo (inc/coh) ratios exhibit an overall upward increasing trend towards the top, despite minor fluctuations (Figure 6).

Sedimentological and geochemical analyses of GC35 revealed five distinct units (Units V to I, from bottom to top; Figure 7). Despite some age uncertainties due to radiocarbon dating limitations, these units encompass the last four historical climate periods and/or transitions up to Recent times: RHIP, DA, MCA, and LIA (Figures 2C, 7). Unit V, however, extends beyond the RHIP and covers a broader time frame from ∼4161 years BP. The RHIP is included in the upper part of Unit V (Figure 7).

The lowermost Unit V (235–144 cm bsf), with uncertainties due to limited ¹⁴C dates, spans from ca. 6,110 to <1,138 cal yr BP (i.e., from 4,161 BCE to <812 CE; Figures 2C, 7). This unit is composed of brownish-to-brownish light green silty mud and contains three coarsening-upward intervals, with very rare primary sedimentary structures (Figure 7). Sediments along Unit V are poorly to very poorly sorted, and consist of terrigenous components, including grains of quartz, K-feldspar, plagioclase and muscovite. In addition, bioclasts such as foraminiferal, bivalve and gastropod shells, as well as mottling indicative of bioturbation (Figures 7, 4E,F), are observed throughout the unit. Terrigenous elements (Si, K, Al, Ti and Fe), clay (%), Ca, and Rb/Zr, Fe/Ca, Ti/Ca, and Sr/Ca ratios exhibit high values with minor short-term fluctuations (Figure 7). Major fluctuations roughly coincide with the coarsening-upward intervals. Similarly, Br and Br/Ti and Mo (inc/coh) ratios remain stable but slightly fluctuating (Figure 7).

Unit IV (144–125 cm bsf) likely covers the DA (Figures 2C, 7). This unit is composed of brownish light green mud/silty mud with homogeneous composition of the coarse and fine fractions. This unit is poorly sorted, largely composed of terrigenous components along with foraminiferal and mollusk shells, and it exhibits a mottled appearance lacking primary sedimentary structures (Figure 7). Likewise, terrigenous elements (Si, K, Al, Ti, and Fe), Br and Rb/Zr, Br/Ti, and Sr/Ca Mo (inc/coh) ratios display a relatively stable and homogeneous trend (Figure 7). Conversely, Fe/Ca and Ti/Ca ratios show an upward increasing trend. Elemental counts of Ca display an anticorrelated trend with Fe/Ca and Ti/Ca ratios (Figure 7).

Unit III (125–95 cm bsf) likely covers the MCA (Figures 2C, 7). This unit is composed of brownish light green mud. Similar to underlying Unit IV, this unit is poorly sorted, largely composed of terrigenous components along with shell bioclasts, and it exhibits a mottled appearance with no primary sedimentary structures (Figure 7). Unit III exhibits constant geochemical values (Figure 7).

Unit II (95–25 cm bsf) spans the LIA (Figures 2C, 7). This unit consists of bioturbated brownish green mud/silty mud, exhibiting a weak fining-upward trend from a sandy-rich basal interval up to 65 cm bsf. Above 65 cm bsf, a weak coarsening-upward trend is observed, accompanied by interbedded coarse-grained intervals from 44 cm bsf to the top (Figure 7). Sediments of Unit II are poorly sorted, primarily composed of terrigenous components, along with shell bioclasts. Abundance of bioclastic components is higher within the coarse-grained intervals. The unit exhibits a mottled appearance indicative of bioturbation and lacks primary sedimentary structures (Figures 4E,F, 7). Terrigenous elements (Si, K, Al, Ti, and Fe), Ca and Rb/Zr display high values with minor, short-term fluctuations up to 44 cm bsf, above which they slightly decrease towards the unit top, with a pronounced decrease in Rb/Zr ratio (Figure 7). Conversely, Fe/Ca, Ti/Ca, and Sr/Ca ratios display an upward increasing trend, as Br, Br/Ti, and Mo (inc/coh) ratios (Figure 7). Furthermore, significant fluctuations occur within the coarse-grained intervals from 44 cm bsf to the top of the unit (Figure 7).

Unit I (25–0 cm bsf) spans the most recent period, from <1880 CE to the time of sediment coring (Figure 2C; Cerrillo-Escoriza et al., 2024a). The sediments at the core top consist of mud/silty mud exhibiting a weak fining-upward trend. This unit is also poorly sorted, largely composed of terrigenous components along with shell bioclasts, and exhibits a mottled appearance with rare occurrences of primary sedimentary structures (Figures 4E,F, 7). Geochemical proxies display a relatively constant, yet fluctuating trend (Figure 7).

In the Motril Canyon, sedimentation over the last ∼2000 years BP was dominated by muddy, fine-grained sediments with high accumulation rates (Figures 2A, 3). Notably, high values of Ca, coupled with moderate to high values of terrigenous elements, mostly in units V, III and I (Figure 3), suggest that detrital carbonate from limestone/dolostone outcrops, most likely from the Alpujárride Complex (Figure 1C; Aldaya et al., 1979; 1981), may have served as a Ca-bearing sediment source transported through the Guadalfeo River drainage system. High sedimentation and mass accumulation rates (1.45 cm⋅yr⁻¹ and 15.21 kg⋅m⁻² yr⁻¹) have also been reported in the recent sedimentary record of the Motril canyon (see Figure 9B in Cerrillo-Escoriza et al., 2024a). These high accumulation rates, along with the predominance of fine-grained sediments—primarily deposited by suspended load and relatively enriched in mica, terrigenous elements, and organic matter (Figures 3–5)—are typically associated with episodic flooding events (e.g., Mendes et al., 2020). The increasing Fe/Ca and Ti/Ca ratios suggest that the main flooding events occurred during Unit II deposition (Figure 3), which may have been driven by river-derived sediment density flows comparable to hyperpycnites (e.g., Mulder et al., 2003). Similar sedimentary patterns have been observed in other inner-shelf systems along the southern Iberian Peninsula (e.g., Mendes et al., 2020) and elsewhere (e.g., de Mahiques et al., 2009; Mojtahid et al., 2018). Fine-grained transport during flood events is interpreted to have occurred primarily via suspension load, though there is also evidence for some degree of saltation (e.g., see detailed frequency curves of Unit II in Figure 5). This is reflected in increases in the sand-sized fraction and Sr/Ca ratios, and a decrease in Ca, indicating reduced inputs of detrital carbonate (e.g., Hodell et al., 2008; Rothwell and Croudace, 2015) (Figures 3, 5A). The coarse grains interpreted as the product of saltation load are mainly composed by bioclasts, such as bivalve shells and benthic foraminifera (Figure 4B). This suggests that the observed increases in grain size could have been driven by higher concentrations of bioclasts. Indeed, Ca and Sr are associated with biogenic inputs, especially from bivalve and gastropod shells, with Sr being linked to aragonitic shells (e.g., Hillaire-Marcel and De Vernal, 2007). Shell fragmentation also suggests some degree of downslope sediment transport (Figure 4B). The bioclast increase, particularly of coarse-sized shells and shell fragments, most likely reflects increased benthic production occurring in shallower areas. There, increased river discharges could have enhanced sediment erosion and redistribution. These bioclasts would have been transported to greater depths, where they eventually accumulated. This interpretation is consistent with the notion that fluvial input can enhance benthic productivity in proximal areas, while hydrodynamic processes facilitate the downslope transport and deposition of coarse biogenic material (e.g., Mendes et al., 2020).

The absence of primary sedimentary structures or evidences of sediment reworking (Figures 3, 4A,B) suggest that deposition primarily occurred under low-energy hydrodynamic conditions. Moreover, sediment remobilization seems to be of minor importance, as the radiocarbon dates, except for one outlier at 100 cm bsf, consistently increase with core depth (Table 1; Figures 2A, 3). This aligns with observations of terrigenous-dominated regions influenced by riverine input during periods of reduced marine winnowing (e.g., Sommerfield et al., 2002; Sommerfield and Wheatcroft, 2007). Further evidence supporting limited sediment transport through the Motril Canyon is given by the absence of transported shelf benthic foraminifera in recent canyon sediments (Cerrillo-Escoriza et al., 2024a). We thus interpret the Motril Canyon primarily functioned as a river-fed system, strongly influenced by fluvial discharges of the Guadalfeo River (Figures 1B,C) during periods of calm hydrodynamic conditions in the last 350 cal. yr BP (Figure 3). The Motril Canyon thus acted as a sediment trap, and therefore its recent sedimentary infill enables the reconstruction of natural and human-induced Holocene paleoenvironmental changes (see Section 5.2. below).

Sediment deposition in the Carchuna Canyon is mainly characterized by coarse-grained facies and very thin to thin-bedded, fine-grained, mica-rich sandy turbidites (Figures 4C,D, 6), which are often enriched in carbonaceous fragments (Figures 4C,D). These fine-grained turbidites, often exhibiting convoluted laminae (Figures 4D–7), are predominantly found within Unit II, with some also present at the base of Unit I (Figure 6). They are interpreted as deposited from turbulent flows in which particles were primarily transported by saltation and rapidly settled (e.g., Lowe, 1979; Stow and Smillie, 2020). Moreover, the high Ca contents, coupled with the occurrence of carbonaceous fragments (Figures 4D, 6), suggests that limestone and dolostone outcrops adjacent to the Carchuna Canyon head provided significant coarse-grained sediment inputs to the regional littoral cell (Figure 1C). Given the location of these outcrops, it is more likely that their redistribution was primarily driven by westward littoral currents under the dominance of easterly winds. Additionally, the Alpujárride Complex may have served as a Ca-bearing source of sediments transported through the Guadalfeo drainage basin (Figure 1C; Aldaya et al., 1979; 1981).

Consequently, the observed sedimentary features suggest transport activity driven by turbidity flows along the Carchuna Canyon during the last 500 years. This interpretation agrees with previously evidence (Cerrillo-Escoriza et al., 2023; 2024a; 2024b): (a) the coarse composition of surficial sediments in the axial channel; (b) low mass accumulation rates (5.40 kg⋅m⁻² yr⁻¹) in the axial channel with a sedimentation rate of 0.49 cm⋅yr⁻¹; (c) high organic matter contents at both the termination of the upper canyon segment (between 350 and 400 m water depth) and the lower canyon segment; (d) the occurrence of marine litter accumulations in the upper canyon segment; (e) identification of bedforms along the axial channel and the adjacent depositional lobe, which are also attributed to high-density turbidity currents; (f) high values of transported shelf benthic foraminifera in the lower canyon segment.

We interpret that longshore drift and wave focusing in the Carchuna Canyon head (Figure 1; Ortega-Sánchez et al., 2014; Cerrillo-Escoriza et al., 2024a) have mobilized coarse-grained sediments subsequently transported by turbidity currents. These transport dynamics are consistent with those observed in littoral systems where canyon heads act as focal points for sediment winnowing and bypassing (e.g., Smith et al., 2018). The limited fluvial discharge of Puntalón ravine to the west (Figure 1B), combined with the energetic wave regime—often amplified by the local irregular seafloor (Cerrillo-Escoriza et al., 2023; 2024a; 2024b)—suggests that, over the last 500 years, sediment transport and deposition in the Carchuna Canyon have been primarily controlled by westward-directed longshore drift, in contrast to the fluvially influenced Motril Canyon. However, other potential triggers for turbidity currents, such as earthquake-induced sediment remobilization, cannot be ruled out. In tectonically active margins, earthquake shaking is known to induce synchronous slope failures across broad regions, generating diagnostic turbidite layers used to reconstruct seismic recurrence intervals (e.g., Goldfinger et al., 2003; Goldfinger et al., 2012; 2013; Moernaut et al., 2014). These earthquake-triggered flows or “seismoturbidites” are commonly funneled through submarine canyons and deposited on the basin floor (e.g., Goldfinger et al., 2012; 2013). The southern Iberian Peninsula, and particularly the SW margin, has experienced significant historical earthquakes over the last 500 years, most notably the well documented 1755 CE Lisbon earthquake and tsunami event (see review by Lario et al., 2011; Álvarez-Martí-Aguilar, 2022). Locally, historical earthquakes have also occurred in nearby coastal towns, such as the 1679 CE Andalusian earthquake and the 1804 CE Motril earthquake (Museo de Historia de Motril, 2023). Therefore, it is plausible that some of the fine-grained turbidites observed at GC26 Unit II (Figure 6) may correspond to such local seismic events, although further chronological and stratigraphic correlation is required to confirm this interpretation. In comparable environments, shelf failures have typically been associated with sediment overloading during storms (e.g., Puig et al., 2004), or with ground shaking and instability caused by regional earthquakes (e.g., Mulder et al., 1998; Goldfinger et al., 2012; 2013).

Finally, recent sedimentation in the Calahonda Canyon reflects an intermediate depositional environment between the Motril and Carchuna canyons. Its sedimentary archive includes a mixture of muddy, fine-grained facies, and coarse-grained deposits (Figures 4, 7), indicating a depositional environment likely influenced by both fluvial inputs and bi-directional hydrodynamic processes. The shelf east of the Calahonda Canyon is primarily influenced by easterly winds (e.g., Ortega-Sánchez et al., 2014; Cerrillo-Escoriza et al., 2024a), able to generate westward-directed shelf currents which most likely transported and deposited coarse-grained sediments, including turbidites. Yet moderate eastward currents formed during westerlies dominance, reaching velocities up to 0.5 m⋅s⁻¹ [see Figure 12A in Cerrillo-Escoriza et al. (2024a)], may also have supplied moderate amounts of sediment. In addition, the adjacent shelf is supplied by small water courses, such as the Gualchos ravine located 5 km to the east (Figure 1B), and the more distant Adra River about 40 km further east. While the Gualchos ravine may provide seasonal, discontinuous sediment input, the Adra River is likely to deliver moderate to limited sediment discharges, with much of its sediment load confined to its proximal deltaic environment (Mendes et al., 2015; Bárcenas et al., 2024). Sediment may be laterally transported by west-southwest-directed longshore drift, driven by the prevailing easterly winds and the rectilinear coastal morphology (Lario et al., 1999), and are eventually trapped at the Calahonda Canyon (Figures 1B, 7). This suggests that the Calahonda Canyon has likely functioned as a longshore-drift-fed system, receiving sediment input from both littoral currents that mobilize coarse-grained sediments—ultimately transported by turbidity currents—and from ephemeral, seasonal streams with intermittent flows. Additionally, the Adra River may have provided moderate amounts of sediment under the influence of easterly winds. Thus, despite the presence of interbedded gravity-driven deposits, the sedimentary infill of the Calahonda Canyon holds potential for reconstructing natural and human-induced Holocene paleoenvironmental changes.

The IRHP (2600–1600 cal. yr BP), described as a wet period (Martín-Puertas et al., 2009), is widely recognized in the southern Iberian Peninsula (e.g., García-Alix et al., 2013; Jiménez-Moreno et al., 2013; Ramos-Román et al., 2018; López-Avilés et al., 2021). There, pollen records from the Sierra Nevada wetland (e.g., Laguna Hondera; Ramos-Román et al., 2018) have extended the IRHP to 2600–1450 cal. yr BP. Within this broad humid phase, an arid Roman Empire Epoch—known as the “Roman Climatic Optimum” (2150–1800 cal. yr BP; McCormick et al., 2012; Bini et al., 2020)—has been reported, likely influenced by both climatic forcing and human activity. This arid interval is also recorded in the Sierra Nevada wetland (e.g., between 2300 and 1800 cal yr BP: Ramos-Román et al., 2018; or between 2400 and 1900 cal yr BP; Ramos-Román et al., 2016).

The IRHP was recorded in the Motril and Calahonda canyons (Figure 1B), albeit with limited radiocarbon ages (Figures 2, 3, 7). In the Motril Canyon, the recorded IRHP spanning from ∼2025 to 1500 cal. yr BP would coincide with the arid Roman Empire Epoch (McCormick et al., 2012; Bini et al., 2020). During this period, sedimentation was dominated by coarse-grained fractions and relatively low sedimentation rates (Figure 3), suggesting a reduced terrigenous suspension input (Durand et al., 2018; Mendes et al., 2020). This interpretation is supported by moderate elemental counts of Si, K, Ti, and Al, as well as by Fe/Ca and Ti/Ca ratios (Figures 3, 7), indicating reduced terrigenous sediment input due to limited Guadalfeo River discharges (Figure 1B). This inference agrees with suggested slow advances of the Guadalfeo deltaic system with rates of ∼0.15 m yr⁻¹ during the IRHP and later (between 2000 BCE and 1500 CE; Jabaloy-Sánchez et al., 2014). The establishment of dry conditions could explain this limited continental export, as interpreted in other shelf environments (e.g., de Mahiques et al., 2009).

The Motril Canyon recorded a shift towards finer-grained sedimentation and an increase in fluvial elemental ratios at the end of the IRHP (Figure 3), suggesting a transition to more humid conditions. This pattern is broadly synchronous with a humid phase that occurred during the decline of the Roman Empire between 1800 and 1600 cal. yr BP, likely associated with negative North Atlantic Oscillation (NAO) conditions that increased the influence of westerly winds over southern Europe, thereby enhancing moisture levels (e.g., Olsen et al., 2012).

Although the end of the IRHP was marked by increased moisture availability, the increase in terrigenous sediment export may have been influenced by additional factors, including intensified human land use. This assumption aligns with the limited flood activity recorded in the southwest Iberian Peninsula during this period (e.g., Thorndycraft and Benito, 2006; Benito et al., 2015; Mendes et al., 2020). During the Roman Empire, the effects of anthropogenic activities such as mining, agricultural and grazing activities on sediment production have been documented in the Iberian Peninsula, even at high altitudes in the southeastern region (e.g., Leblanc et al., 2000; Boone and Worman, 2007; García-Alix et al., 2013; Jiménez-Moreno et al., 2013; Ramos-Román et al., 2016; 2018; López-Avilés et al., 2021; Díez-Herrero et al., 2024). For example, mining exploitation of copper, silver, and gold increased significantly since ∼2500 cal. yr BP (Leblanc et al., 2000), with a peak in activity occurring between 0 and 200 CE (2000–1800 cal. yr BP; Davis et al., 2000; Delgado et al., 2012).

Between 1500 and 1000 cal. yr BP, the climate in northern Europe experienced a deterioration characterized by rapid cooling and aridification, a period commonly referred to as the Dark Ages (e.g., Magny, 2004; Regattieri et al., 2014). Pollen records from the central and southern Iberian Peninsula also suggest that arid conditions prevailed during the DA (e.g., Carrión, 2002; Jiménez-Moreno et al., 2013; Ramos-Román et al., 2016; Ramos-Román et al., 2018). Similar climatic conditions have been detected in marine records from the Alboran Sea (Fletcher and Sánchez-Goñi, 2008; Combourieu-Nebout et al., 2009; Nieto-Moreno et al., 2013; 2015).

Off the Guadalfeo delta system, this period was recorded and dated in the Motril Canyon (Figure 3). Initially, sedimentation during the DA was characterized by coarse-grained fractions akin to those deposited during the preceding IRHP. However, a gradual transition to fine-grained sediment deposition occurred, accompanied by increased sedimentation rates, and coherent with increases in elemental counts of Si, K, Ti, and Al, as well as Fe/Ca and Ti/Ca ratios (Figure 3). This suggests a gradual rise in terrigenous suspension input to the shallow-marine environment, likely driven by changes in sediment production in the hinterland. The rise in fine-grained sediment input could be related to moderate rainfall conditions in the Guadalfeo River basin. Comparable evidence of moderate rainfall has also been reported in other southern Iberian basins, such as the Guadiana Basin, which recorded flood activity between ∼1200 and 1000 cal. yr BP (Ortega and Garzón, 2009; Benito et al., 2008; 2015; Mendes et al., 2020). However, a positive NAO phase during this period may have contributed to increase aridification over the Guadalfeo River region (Trouet et al., 2009; Olsen et al., 2012).

As a result, factors other than climatic changes may have triggered the rise in terrigenous sediment supply to the Guadalfeo delta system. Widespread soil erosion and land degradation caused by intensified land use appear to have largely contributed to the sediment increase. Historical accounts suggest that the decline of Roman influence in Iberia at ca. 1500 cal. yr BP initiated a period of significant demographic changes. In fact, settlement density in southwestern Iberian Peninsula increased sixfold during the following 500 years, particularly after the Muslim invasion at ca. 1200 cal. yr BP (Boone and Worman, 2007). Such intensified land use likely exacerbated soil erosion, contributing to the increase in terrigenous sediment supply to the Guadalfeo delta (e.g., Jabaloy-Sánchez et al., 2014). A similar phenomenon occurred in the central Adriatic, where sedimentation rates quadrupled between 1100 and 700 cal. yr BP due to changes in land use that enhanced terrigenous sediment input to the shelf (Oldfield et al., 2003).

The MCA (1050–650 cal. yr BP) was characterized by warm conditions driven by a persistent positive NAO (e.g., Trouet et al., 2009; Moreno et al., 2012; Olsen et al., 2012). In the southern Iberian Peninsula, several pollen records document a warmer and relatively arid climate during the MCA (e.g., Jiménez-Moreno et al., 2013; Ramos-Román et al., 2016; 2018; Ramos-Román et al., 2018). These arid conditions were associated with a low frequency of floods and reduced fluvial inputs to marine basins (Moreno et al., 2012, and references therein). Evidence of drought is particularly well documented in sediment records from Sierra Nevada wetlands, such as the Laguna de la Mula (e.g., Jiménez-Moreno et al., 2013).

Off the Guadalfeo delta system, the MCA is also recorded in the Motril Canyon (Figure 3). Sedimentation during the MCA was predominantly fine-grained, with higher sedimentation rates compared to the DA (Figure 3). Our proxy data suggest a sustained influx of terrigenous material into the shallow-marine environment, driven by persistent sediment production in the hinterland. Although sedimentation patterns were broadly similar during the DA and MCA periods, evidence of moderate rainfall conditions appears less pronounced during the MCA (Figure 3). This suggests that widespread soil erosion and land degradation—primarily due to intensified human land use—played a significant role in increasing terrigenous sediment production. Despite generally dry conditions, geoarchaeological studies from the southeastern Iberian Peninsula have identified notable paleo-flood events during the Andalusian Almohad Taifa period (late 12th to early 13th century CE) (Díez-Herrero et al., 2024). A stunning example is the “Roman theatre of Acci” (modern-day Guadix), which preserves evidence of extreme hydrological events associated with the Medieval Warm Period. While such findings suggest the possibility of small, localized episodes of anomalous rainfall conditions, such events would have been sporadic and restricted regionally (e.g., Ortega and Garzón, 2009; Benito et al., 2008; 2015; Mendes et al., 2020), consistent with the influence of NAO dynamics on moisture availability throughout most of Iberia (Sánchez-López et al., 2016).

In terms of anthropogenic effects on sediment production, major land-use changes—including deforestation, cultivation, and agricultural intensification—initiated approximately 200 years prior to the MCA (Boone and Worman, 2007). These practices likely contributed to increase the sediment supply to the shelf. In the southwestern Iberian Peninsula, this drastic land surface degradation led to the abandonment of most rural settlements by the mid-12th century CE (ca. 800 cal. yr BP; e.g., Boone and Worman, 2007). Consequently, the combined impact of arid conditions and human-driven landscape changes accelerated soil erosion during the MCA, increasing terrigenous sediment export to the Guadalfeo delta system.

Two climatically distinct periods can be distinguished over the last ∼600 years. The first is the LIA from 650 to 150 cal. yr BP, and the second is the Industrial Period (IP; 150 cal yr BP–present). The LIA is interpreted as an overall humid period in the Guadalfeo region (Figure 1B). In the studied sediment cores, this period is recorded in the Motril, Carchuna, and Calahonda canyons (Figures 3, 6, 7). This period is marked by high rates of fine-grained sediment deposition, suggesting increased terrigenous input of suspension loads. This interpretation is supported by the occurrence of increased elemental counts of Si, K, Ti, and Al, as well as by high Fe/Ca and Ti/Ca ratios (Figures 3, 6, 7). The increase in fine-grained sediment supply to the continental shelf during the LIA likely reflects a period of increased rainfall in the Guadalfeo River basin, correlated with a negative NAO phase (e.g., Trouet et al., 2009; Fletcher et al., 2013). This trend is consistent with the suggested rapid advancement of the Guadalfeo Delta, at rates of ∼3.3 m yr⁻¹ from 1500 CE to the present day (Jabaloy-Sánchez et al., 2014).

An increase of fluvially derived proxies has been previously documented in the Alboran Sea (e.g., Nieto-Moreno et al., 2011; 2015) and in inland records (e.g., Moreno et al., 2012; Ramos-Román et al., 2016; Ramos-Román et al., 2018). Equivalent phases of fine-grained deposition driven by enhanced river discharges have been documented elsewhere during the LIA (Abrantes et al., 2005; Lebreiro et al., 2006; Bartels-Jónsdóttir et al., 2006; 2015; Mendes et al., 2020). Pollen fluctuations in several Iberian records suggest that the LIA was not a climatically stable period, and numerous short-term oscillations occurred (e.g., Ramos-Román et al., 2016; García-Alix et al., 2017; Oliva et al., 2018). It is also worth mentioning that the humid conditions inferred from our LIA records coincide with rainfall reconstructions for the past 500 years in southern Iberia based on documentary sources (e.g., Rodrigo et al., 1999; Sánchez-García et al., 2019; Sánchez-García and Schulte, 2023). Historical flood records from the southern Iberian Peninsula have revealed alternating periods of increased (e.g., 1540–1560, 1720–1745, and 1860–1891) and decreased (1790–1845) flood frequencies. Additionally, human activities during the LIA also impacted the southern Iberian Peninsula. For instance, the expansion of cereal agriculture and transhumant livestock practices between the 16th and 19th centuries CE led to episodes of extensive soil erosion (e.g., García-Ruiz, 2010). Furthermore, demographic changes and mining activities during the 18th and 19th centuries CE resulted in a significant deforestation of the Iberian Peninsula (Martín-Rosales et al., 2007).

Humid conditions prevailed during most of the IP and into the early 20th century CE in the southern Iberian Peninsula, as evidenced by instrumental precipitation data (Rodrigo et al., 1999; Sánchez-García et al., 2019; Sánchez-García and Schulte, 2023). However, increased local aridity and/or human-induced desertification is reported in the Sierra Nevada wetland records (e.g., García-Alix et al., 2013; Ramos-Román et al., 2016). Indeed, a general decreasing trend of rainfall has been observed in the southern Iberian region from 1960 onwards (Rodrigo et al., 1999), as well as elsewhere in the Iberian Peninsula (Gallego et al., 2011; Rodrigo and Trigo, 2007) during the last century. Our sedimentary record at Motril Canyon shows a general decrease in fluvial-derived material during the IP (Figure 3), suggesting a diminished supply from the Guadalfeo River.