Holocene aeolian phases and human settlements along the Atlantic coast of southern Spain

Abstract

A combined geomorphological, radiocarbon dating, archaeological and historical approach permits a refining of the age of the coastal dune systems related to estuaries in the Gulf of Cádiz. Three dune systems are distinguished in this paper. The oldest one, D1, which accumulated under prevailing WSW winds during the first millennium bc, overlays both the occupational horizons of Late Neolithic-Early Copper Age (fourth millennium bc) and the‘lithic workshop levels' (fourth to second millennia bc). The middle dune system, D2, containing both Roman and medieval remains, accumulated between the thirteenth or fourteenth centuries and the seventeenth century ad. The youngest D3 system is associated with the time of building of watchtowers in the seventeenth century ad but extends to the present; it is related to SW prevailing winds. We explain the absence of aeolian deposits prior to 2700 cal. BP as the result of trapping of a large part of the sediment supply in the estuaries, which starved the neighbouring beaches and aeolian settings. Aeolian accumulation reached significant values when sedimentation in the coastal zone changed from being mainly aggradational in the estuaries (6500–2700 cal. BP) to mainly progradational in spit barriers and related dunes (post 2700 cal. BP). The present analysis of aeolian systems suggests a non-direct correlation, at least in some cases, between coastal progradation of spit barriers and aridity.

Archaeoseismic record at the ancient Roman City of Baelo Claudia (Cádiz, south Spain)

“…from the Decumanus maximus) into the D 1 and D 2 Dune systems, previously defined for southern Spain (Borja et al, 1999). From the palaeoseismic point of view the most interesting formation is the already mentioned bDemolition HorizonQ, which appears either between these two colluvial formations at the base of the ancient paleocliff (Sector of the Temples) and/or directly mantling the plastic clayey substratum over the rest of the lower sector of the City (Fig.…”

“…2). Two undisturbed aeolian levels bearing Bronze Age (D 1 ) and Roman (D 2 ) remains (Borja et al, 1999), seal the deformed materials indicating that main deformational events occurred before the Bronze Age (Goy et al, 1995).…”

“…4) with Geotechnical data from Vorsevi (1993Vorsevi ( , 1995 thickness ranging from 0.9 (S2) to 2.1 m (S5), and thinning towards the coast (Fig. 3), where the most recent Dune systems (D 1 of Borja et al, 1999) are dominant. These colluvial deposits are constituted by rounded and subangular gravels and boulders embedded in a clayey-sandy matrix, interpreted as colluvial toe-cliff deposits.…”

“…From the Decumanus maximus to the shore, the rest of the city (private houses and fish-Garum-factories) lays on poorly consolidated aeolian sands. The older deposits correspond to the first Holocene aeolian system widely developed in the south Spanish littoral between 2700 BP and the early 2nd century BC (pre-Roman D 1 System of Borja et al, 1999). Recent submarine and geoelectrical surveys (Alonso Villalobos et al, 2003) carried out in the present bay and beach testify the ancient roman paleo-shoreline as well as different harbour structures (boat ramps) built on beach deposits associated to the Roman dune System (D 2 ) of Borja et al (1999).…”

The coastal archives of the last 15ka in the Atlantic–Mediterranean Spanish linkage area: Sea level and climate changes

“…1). Much information comes from coastal sectors studied in previous papers (e.g., Zazo et al, 1994Zazo et al, , 1999aZazo et al, c, 2005Borja et al, 1999;Dabrio et al, 1999Dabrio et al, , 2000Goy et al, 1996Goy et al, , 2003Lario et al , 2000Lario et al , , 2002Luque, 2002;YIl et al, 2003), and from Doñana-Huelva (Rodrí-guez-Ramírez et al, 1996Ruiz et al, 2005;Cáceres et al, 2006). The paper also ineludes data from Portuguese (Bard et al, 2000); M39-008 (Cacho et al, 2001; MD95-2043 (Cacho et al, 1999(Cacho et al, , 2001Sánchez-Goñi et al, 2002);H-658 C (de Menocal et al, 2000).…”