the great gibraltar sand dune

One of them, and a very spectacular one at that, is the Great Gibraltar Sand Dune or Catalan Bay Sand Dune. This is an imposing sandy slope that stretches for more than 1km on the eastern face of the Rock, rising form near sea level to 300m. Currently the sand dune has a gradient of 30˚ but this is due to modifications carried out during the installation of water catchments in the 20th century. Soundings reveal that the dune has a maximum thickness of about 30m.

Known as a fossil sand dune, it is now inactive as it is no longer receiving new sand and has therefore consolidated having been cemented by carbonation. How did this great mass of sand accumulate on the Rock? The morphology of the Rock of Gibraltar was similar to today during the final phases of the Pleistocene, a time that experienced substantial climatic changes – very cold periods known as glaciations. These caused much lower sea levels, as much as 120m in the Mediterranean which exposed a large coastal shelf at the foot of the Rock, with the beach at a maximum of 4.5km out from the current coastline during the coldest periods. These plains were largely covered in sand forming aeolian (wind-blown) dunes. These sands were carried by the prevalent wind in Gibraltar, the Levante, towards the eastern face of the Rock where they would become trapped by the cliffs and escarpments produced by large landslides and rock falls.

The dune consists of different sections of sand and rock falls. The section closest to the beach was formed approximately 130,000 and 90,000 years ago. The upper section of the dune, which forms a large sandy slope, stopped forming between 49,000 and 37,000 years ago. These dune’s sand deposits were able to climb higher by adapting to the rock falls constantly collapsing from the cliffs above.

As we have seen, this dune was formed during the period Neanderthals lived in Gibraltar’s many caves and so this landmark would have been part of their daily landscape. We even know they climbed it to reach higher caves such as Ibex Cave at the very top of the Great Dune.