Since the last Holocene sea level rise, about 6900 BP, a series of dep
ositional littoral landforms has been generated at the outlet of the G
uadalquivir River, with progradation along the predominant longshore d
rift (towards the east).The first coastal progradation occurred betwee
n 6900 and 4500 BP. The Donana and (perhaps) La Algaida spits, both as
sociated with the oldest and highest marshland in the Donana National
Park, are assumed to have been developed at an early stage. Originally
, the Guadalquivir estuary was wider and deeper than now, and its envi
ronment was mainly marine. The oldest littoral formations have been da
ted as ca. 4735 BP. They show erosional events, and indicate the break
ing-up of earlier spit-barriers to form inlets. The marine environment
became increasingly dominant, with heavy erosion of cliffs and a retr
eating coastline. This period was followed by another sedimentary cycl
e (4200-2600 BP) that surrounded the earlier eroded barriers. The size
of the estuary decreased due to the increasing marsh deposits, and a
fluvial environment was born. About 2600 years ago, progradation gave
way to a new period of intense erosion. The resulting morphology of li
ttoral strands and erosional surfaces permitted the return to a marine
environment. The shoreline again retreated. From 2300 BP, coastal pro
gradation has prevailed, with an erosional interruption at 1000 BP. Th
e present-day outlet of the Guadalquivir is an estuarine delta of inac
tive marshland (the Donana National Park), the dominant environment is
fluvial. Copyright (C) 1996 Elsevier Science Ltd