Littoral zone and rapid climatic changes during the last 20,000 years. The Iberia study case

Abstract

The shifting position of the Polar Front between 20,000 yr BP and 6,000 yr BP had a different climatic response in the Iberian littoral zone north and south of 40°N. Available data from karstic sedimentology, pollen, coccolith floras and morpho-sedimentological studies supported by 14C measurements, indicate a cold-dry climate in the Mediterranean region and a cold-cool and humid climate in the Cantabrian region during the last Glacial Maximum. However, climatic conditions during the Younger Dryas cold event were dry but not cold in the Mediterranean and humid, but less than today, and cool in Cantabria. By contrast to the west of the Gibraltar Strait (Atlantic region) the climatic conditions were humid and temperate both during the last Glacial Maximum and during the Younger Dryas. Coccolith flora data indicate surface sea-water temperatures slightly warmer for the Atlantic region of South Iberia than for the adjacent Mediterranean. After the Holocene sea-level maximum (6,900 yr BP), two phases of major offshore progradation are recorded in southern Iberia, indicating the occurrence of two main sea-level oscillations since the Holocene maximum, a slight fall (6,900-2,700 yr BP) followed by a slightly rise (2,400 yr BP-Present). Sea level was never higher than the Holocene maximum position during this latter period.