That region repeatedly experienced green periods, as a result of periods of heavy rains. They gave rise to the formation of Lagos and Ríos about 9,000 years ago. The Desert of Arabia that was a valley had a very different time from the current one.
This is the key finding of a team that documented an ancient landscape sculpted by water in Rub al-ár. It is one of the largest and dry deserts in today’s world. The article has been published in Communications Earth & Environment.
Overflowing lake
The team is directed by the University of Geneva (Switzerland), and the University of Science and Technology Rey Abdullah (Kaust). He documented the presence of an old lake, rivers and a large valley formed by water.
«Based on an ages series, it seems that the lake reached its maximum splendor about 9,000 years ago. It was during the wet period of green Arabia. This extended between 11,000 and 5,500 years ». This was stated by the first author, Dr. Abdallah Zaki, in a statement.
It is estimated that the lake was huge, with an extension of 1,100 square kilometers and 42 meters deep. «For rainfall, the lake finally overflowed. It caused a great flood and excavated a valley of 150 km long in the desert floor ».
Scientists believed that the origin of the monsoon rains came from the African monsoon. It is demonstrated by the sediments that could be traced along a distance of 1,100 km. They come from the riser mountains throughout the Red Sea, very close to Africa.
Changing landscape
The Desert of Arabia that was a valley had radically different climates from the current ones. The rainfall was not scarce, but sometimes strong and intense, which caused rapid changes already large scale in the landscape. «Lacustrine and riverside landscapes were formed, along with the conditions of grasslands and savanna. They led to the expansion of groups of hunters and collectors, as well as pastor populations, so today is an arid and sterile desert ». This is confirmed by the abundant archaeological evidence in the area throughout its old networks of lakes and rivers.
«6,000 years ago, Rub al-áro experienced a strong decrease in rainfall. Dry and arid conditions began, forcing populations to move to more cozy environments and modify the lifestyle of nomadic populations.
