“…S6 ). This lack of alluvial records has long prevented an understanding of the response of hydrosystems to the 8.2 ka climatic event, which remained totally unknown 23 . Figure 3 ( A ) Transverse section across the Cha07 palaeochannel infilling showing the main litho-stratigraphic units, positions of radiocarbon datings (2σ cal.…”
Section: Resultsmentioning
confidence: 99%
“…This sedimentary gap also concerns the entire alluvial record of NE Morocco, which extends from 8700 to 7300 cal. BP 25 , and North Africa as a whole 23 . We can therefore question why such intense fluvial activity does not leave any flood deposits preserved in the floodplains.…”
Section: Discussionmentioning
confidence: 99%
“…Regarding depositional settings, there is a notable lack of Holocene flooding dates coming from palaeochannels 15 . Tunisian alluvial syntheses also provide no evidence of any fluvial response to the 8.2 ka event, mirroring the long-unresolved “missing event” in the SW Mediterranean 23 . As for Iberian records, it is interesting to see that Early Holocene deposits as a whole are particularly underrepresented 21 , 24 , which may be partly a problem of dating strategies.…”
The Early–Mid Holocene transition is a period of profound changes in climatic mechanisms and hydrological features in Europe and North Africa. The melting of the Laurentide ice sheet led to an oceanic and atmospheric reorganisation in the North Atlantic, while the Mediterranean underwent a major hydrological shift. The impacts on Mediterranean rivers remain unclear, as there are few records documenting responses to the 8.2 ka event (the main Holocene climatic degradation). We present a fluvial record from Eastern Morocco documenting detailed hydrological variations from 8200 to 7500 cal. BP and their climatic forcing. A major hydrogeomorphic evolution of the Charef River occurred at that time, marked by two major incision stages close in time, under hyper-arid conditions at 8200 and ca. 7500 cal. BP. The impacts of these phenomena on the alluvial plains and associated archaeological records during Neolithisation, a major process in human history, currently remain unidentified. This new record sheds light on the fluvial response to the 8.2 ka event in North Africa and why other records are missing. We also bring new insights into the hydrological disruption at the Early–Mid Holocene transition, which was driven by the end of deglaciation combined with insolation and solar forcing. Furthermore, centennial solar variability may have paced river activity in the Moulouya basin and arid regions of North Africa.
“…S6 ). This lack of alluvial records has long prevented an understanding of the response of hydrosystems to the 8.2 ka climatic event, which remained totally unknown 23 . Figure 3 ( A ) Transverse section across the Cha07 palaeochannel infilling showing the main litho-stratigraphic units, positions of radiocarbon datings (2σ cal.…”
Section: Resultsmentioning
confidence: 99%
“…This sedimentary gap also concerns the entire alluvial record of NE Morocco, which extends from 8700 to 7300 cal. BP 25 , and North Africa as a whole 23 . We can therefore question why such intense fluvial activity does not leave any flood deposits preserved in the floodplains.…”
Section: Discussionmentioning
confidence: 99%
“…Regarding depositional settings, there is a notable lack of Holocene flooding dates coming from palaeochannels 15 . Tunisian alluvial syntheses also provide no evidence of any fluvial response to the 8.2 ka event, mirroring the long-unresolved “missing event” in the SW Mediterranean 23 . As for Iberian records, it is interesting to see that Early Holocene deposits as a whole are particularly underrepresented 21 , 24 , which may be partly a problem of dating strategies.…”
The Early–Mid Holocene transition is a period of profound changes in climatic mechanisms and hydrological features in Europe and North Africa. The melting of the Laurentide ice sheet led to an oceanic and atmospheric reorganisation in the North Atlantic, while the Mediterranean underwent a major hydrological shift. The impacts on Mediterranean rivers remain unclear, as there are few records documenting responses to the 8.2 ka event (the main Holocene climatic degradation). We present a fluvial record from Eastern Morocco documenting detailed hydrological variations from 8200 to 7500 cal. BP and their climatic forcing. A major hydrogeomorphic evolution of the Charef River occurred at that time, marked by two major incision stages close in time, under hyper-arid conditions at 8200 and ca. 7500 cal. BP. The impacts of these phenomena on the alluvial plains and associated archaeological records during Neolithisation, a major process in human history, currently remain unidentified. This new record sheds light on the fluvial response to the 8.2 ka event in North Africa and why other records are missing. We also bring new insights into the hydrological disruption at the Early–Mid Holocene transition, which was driven by the end of deglaciation combined with insolation and solar forcing. Furthermore, centennial solar variability may have paced river activity in the Moulouya basin and arid regions of North Africa.
“…4). The youngest phase of maximal tufa deposition at ASI has only been faintly observed in Morocco, where only a few well-dated Holocene tufa deposits (Andrews et al, 2000;Delannoy et al, 1993;Delgado Castilla, 2009;Durán, 1996;García-García et al, 2014;Martìn-Algarra et al, 2003;Wolf et al, 2021) and from Morocco (Azennoud et al, 2022;Boudad et al, 2003;Depreux et al, 2021;Falguères et al, 2016;Lefèvre, 1989;Mercier et al, 2009;Rousseau et al, 2006;Weisrock et al, 2008) (Durán, 1996) and in northern Morocco (Rousseau et al, 2006;Weisrock et al, 2008). Localisation of sites is shown in Fig.…”
Section: Asi Tufa Chronology Compared To Other Regional Tufas and Its...mentioning
confidence: 99%
“…Figure 4. Chronological distribution of tufa deposits from southern Spain(Andrews et al, 2000;Delannoy et al, 1993;Delgado Castilla, 2009;Durán, 1996;García-García et al, 2014;Martìn- Algarra et al, 2003;Wolf et al, 2021) and from Morocco(Azennoud et al, 2022;Boudad et al, 2003;Depreux et al, 2021;Falguères et al, 2016;Lefèvre, 1989;Mercier et al, 2009;Rousseau et al, 2006;Weisrock et al, 2008) including ASI (this study, in red) compared to the evolution of Greenland δ 18 O (North Greenland Ice Core Project members, 2004) and Mediterranean forest at the SW Iberian margin (MD95-2042; Sánchez Goñi et al, 2008) during the last climatic cycle. MIS: Marine Isotopic Stage.…”
Abstract. In the last few decades, multidisciplinary research on
calcareous tufas as palaeoenvironmental and palaeoclimatic records has
intensively grown, which has provided an increasing number of well-documented
sites. Consequently, inter-site comparisons and regional- to
continental-scale reviews have developed, discussing the link between tufa
distribution and climate or providing diachronic comparisons of climatic
and environmental conditions prevailing during Quaternary interglacials
(and interstadials). This paper proposes such a review for the southeastern
Mediterranean area, including new dating and isotopic data from Aït
Said ou Idder (northern Morocco) to be compared with available regional
data, in order to discuss the intensity of some humid periods of the last
125 kyr. According to several radiocarbon and U–Th dates, three chronological phases
are indeed identified at Aït Said ou Idder: the Holocene, the
Dansgaard–Oeschger (D–O) interstadial 8 and the Marine Isotopic Stage (MIS) 5e. Similarly, other tufa
deposits from both Morocco and southern Spain (mostly Andalusia) appear to
have preferentially developed during interglacial or interstadial periods, marked
by maximal developments of the Mediterranean forest as reported in the
palynological records from regional marine cores. Furthermore, isotopic data
(δ18O and δ13C) from Aït Said ou Idder (and
from other southeastern Mediterranean tufa deposits where available) suggest no
significant difference in terms of temperature or air mass circulation
between the Holocene, D–O 8 and MIS 5e. In terms of humidity
conditions, no evidence of strong aridity is recorded even if D–O 8
appears drier than both interglacials. Conditions seems slightly
wetter during the Holocene than during MIS 5e, but δ13C
values at Aït Said ou Idder could also reflect strong differences in
the seasonality of these interglacials. We demonstrate that calcareous tufa
deposits have promising potential for discussing, in both space and time,
the climate variability in the southeastern Mediterranean area, but new
investigations, including dating and stable isotopes, are required to
accurately feed such discussions.
Imagined conceptsmade real by down-to-earth field verification, validated modelling, and using available technologies and empirical methodsare fundamental to research outcomes in geomorphology. This article reviews the functions that consequential concepts have served: as overall driving and embracing stimuli, or playing permissive roles at lower levels within projects; when they have come to the fore and declined in usage; how knowledge of them gets spread and tested; and where needs seem to be driving for the future. Within fluvial geomorphology there is demonstrably a multiplicity of conceptual approaches. Modern times also now involve greater external appraisal including financial and management control and research and teaching quality assessments. These are taking place in parallel with novel environmental changes that themselves pose new needs for hazard understandings and safeguarding. Challenges to address for practical reasons include forecasting the likely future geomorphic effects of climate change, tracking system impacts from the spread of human hardware across landscapes, and monitoring pollutant incursions into fluvial systems. Nevertheless, conceptual progress in understanding is also fundamentally dependent on advancing 'blue skies' research objectives. In a changing world, geomorphology has to pursue holistic goals and the multi-temporal and multi-scale spatial appreciation of landform development, and how this relates to other changing global systems, but also to grow what it conceives of doing for the public good.
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