# Environmental Changes and Cultural Transitions in SW Iberia during the Early-Mid Holocene
## 4 Discussion
### Vegetation Trends and Evolution of Coastal Environments  
During the Early Holocene, the post-glacial marine transgression was progressively drowning the exposed continental shelf of the southwestern Iberian coast with a rapid sea level rise between _ca._ 13 ka BP and 7-6.5 ka BP, although with different responses depending on the geographic location and topography [27]. Initially, until _ca._ 10 ka BP, the first stages  
Figure 6: (**a**) Variations in \(\delta^{18}\)O in GRIP core [82]; (**b**) sea level changes around SW Portugal (Quarteira [83]; Ria Formosa [84]; Algarve and Central Portugal [74] and global [85] and Zr/Rb ratio (notice the reversed scale); (**c**) sea surface temperature (SST) reconstructions for the Gulf of Cadiz (alkenone Uk37 SST derived for core M39-008 [75]) and Mg/Ca SST derived for the Alborán Sea (ALB2 [76]); (**d**) Ti, Fe, and Mn, weathering proxies, as indicative of land moisture; (**e**) Al, Si, Sr and Ca, representative of elastic sedimentation, serve as proxies for activity of marine currents; (**f**) Ca/Si, carbonate vs. silicidastics, and Zr/Al and Si/Al, proxies of siliciclastic grains vs. matrix, as indicative of land derived vs. bioclastic (marine) inputs; (**g**) sedimentation rate for core 19-01 for the 12–6 ka BP period. of the river valleys inundation resulted in pre-estuarine palaeovalleys and transitional areas of fluvial-saltmarsh deposits as the main coastal landscapes [25; 86; 87; 88; 89]. For this period until _ca._ 9.2 ka BP, the core 19-01 indicates the existence of forests composed of mesophilous trees, and Mediterranean trees and shrubs which defined the onset of the Holocene as a warm phase. Mediterranean and high mountain pines were also present, although in low values, being that the latter (_Pinus sylvestris- nigra_ type) may be a reminiscence of the continental climate of the previous glacial period, as reported in other deposits [90]. These conditions have been also inferred in continental deposits in the Guadiana Estuary and the Medina Lagoon, where the presence of open land indicators and high-mountain pines were recorded, respectively [91; 92]. In this regard, it has been found that the hydrological response in some Western Mediterranean areas during the Early Holocene maintained prolonged arid conditions, with shallow lake levels followed by an increase of moisture _ca._ 10-9 ka BP [93]. This may have been linked to insolation and seasonality changes due to the orbital variability, the presence of the Laurentide and Fennoscandian ice sheets in the North Atlantic Hemisphere, and a series of ice rafted debris (IRD) provoking immediate ocean surface coolings associated with dry conditions in the Mediterranean region [1; 94; 95]. Some of these events fall into this period (Figure 7) and two of them appear to have triggered a reaction in the vegetation with a decrease of mesophilous trees and an increase of Asteraceae immediately after 10.3 ka BP, and a retraction of mesophilous and Mediterranean forests with a parallel rise of Mediterranean shrubland and xerophytic taxa after 9.4 ka BP. Diverse records from Greenland show anomalies in the mean \(\delta^{18}\)O curves _ca._ 9.95 and 9.3 ka BP interpreted as temperature irregularities, but also to changes in moisture sources and/or transport paths [96; 97]. The slight delay in the vegetation reacting to these events indicates that changes in terrestrial landscapes were not immediate. Regarding the evolution of the coast, the period between _ca._ 10-7 ka BP is also coincident with a phase of intense marine influence due to the marine transgression into the river valleys of the SW Iberian margin, transformed in estuaries by drowning [25; 86; 87; 88; 89]. As a result, salt marshe developed along the littoral of the Gulf of Cadiz and a landward shift of the boundary between marine and fresh waters took place, with a consequent increase of saline environments [25]. High values of foraminiferal linings were recorded between _ca._ 9.5 to 8 ka BP, probably related to the development of estuaries.