Sahara sends dust to Canary Islands for 4.6 million years
Sahara dust cover covering the Canary Islands.. Picture capture by Nasa Terra Satellite. EFE/NASA -EDITORIAL USE ONLY-NO SALES-NO ARCHIVE-
Sahara dust cover covering the Canary Islands. Picture capture by Nasa Terra Satellite. EFE/NASA -EDITORIAL USE ONLY-NO SALES-NO ARCHIVE-
The world's largest desert sends dust waves across the Atlantic ocean to Europe for at least 4.6 million years. EFE/Alejandro Lomoschitz
Las Palmas, Spain, July 23 (efe).- The world's largest desert, the Sahara, has sent dust waves across the Atlantic ocean to Europe for at least 4.6 million years, particles trapped in fossilised soils have revealed.
The discovery was made after testing soil samples from Fuerteventura and Gran Canaria, two of the oldest islands in the Canary Islands.
The age of the Sahara Desert has become a point of controversy over the last two decades.
Some scientists have argued that around 4,000 or 5,000 years ago it was green with swamps and lakes (Sincell, in "Science", 1999).
Other experts believe that its transformation into a desert started seven million years ago when the Tethys Ocean contracted to become the Mediterranean Sea (Zang, in "Nature", 2014).
A study published this month by the United States Geological Survey (USGS) and the University of Las Palmas de Gran Canaria (ULPGC) in the scientific journal "Palaeogeography, Palaeoclimatology, Palaeoecology" led to a new contribution to the debate.
The research focused on following the trail of the “calima”, a specific weather phenomenon on the Canary Islands that occurs every year when the wind drags hundreds of tons of dust from the Sahara Desert towards the Atlantic Ocean.
The Ocean Drilling Program (ODP), an international project that researches ocean basins, reached similar conclusions years ago.
The study revealed that the seabed in two points on the west coast of Africa contained sediments that came from the Sahara and the Sahel for more than 6.5 million years.
Despite the evidence, it is difficult to determine if the sediments were dragged by rivers or the wind.
Researchers Daniel Muhs, of USGS, Joaquín Meco, of the biology department at ULPGC, Alejandro Lomoschitz, of the Institute of Oceanography and Global Change of ULPGC, and the rest of authors who signed the study demonstrated that the Sahara has been a source of dust on the Canary Islands for 4.6 million years and the Sahel for just under four million years.
African sediments were trapped in nine fossil soils (paleosols) on Fuerteventura and Gran Canaria.
Their age was dated due to the presence of lava or marine fauna enclosed: 4.8-2.8 million years (Agua Tres Piedras), 3.09-2.09 million years (Cliffs of El Mármol), 2.3-1.4 million years (Ingenio) and 400.000 years (Punta de Arucas).
The researchers found particles of quartz and mica in the soil, two main components of dust from African limestone that cannot be found on the Canary Islands. EFE