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Gibraltar’s bottom waters

30 January 2012

At www.sciencedaily.com/releases/2012/01/120125113147.htm there is a report on research off the coast of Spain near Gibraltar and in the Gulf of Cadiz where sediment cores were drawn up for study. The Strait of Gibraltar re-opened just 6 million years ago, fairly recent in the geological time-scale. Way down on the bottom off Gibraltar the Mediterranean waters are pouring into the Atlantic like a cascade. As the Mediterranean is more salty than the Atlantic it sinks, plunging 1000 metres downslope and scours the sea floor carving out canyons and building up mountains of mud. It is this mud that is being explorred as it holds a record of climate change (the Ice Ages) and tectonic activity in the region. The latter is important as we have a hypothetical tectonic pulse at the junction of the African and European plates. Such jolts at the plate boundaries are thought to create major earthquake events – and tsunamis. Therefore large dumps of sediment on the sea floor are an interesting feature to analyse in more ways than one.

The Strait of Gibraltar was at one time a barrier to the Atlantic waters and the seven drill sites were picked out in order to understand what was going on there. They are said to cover, at least, four major Ice Ages (funny how it is always four when textbooks talk of 17 and upwards) and these will be used in conjunction with Greenland ice cores (comparitive evidence) and other land based records.

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