Wednesday, May 17, 2017
Short Story: A Forecast of Egyptian Civilisation
Mai Samih listens to the story of civilisation in Egypt from a geological perspective.
Rocks and earth layers have as much to say as a drawing on a temple about the past, maybe even more. Head of the Department of Geology and professor of Geo-Archaeology at the Faculty of Science at Cairo University Mohamed Abdel-Rahman Hemdan said as much at a seminar at Beit Al-Sinary in Cairo in March when he claimed that “the past is the key to the present.”
“We geologists study the present to understand what happened in the past. However, that past is also the key to the present because archeologists have learned much about how the climate in particular has changed over time. This is a new trend we are now trying to work with,” he said.
The climate is the weather over the long term, Hemdan said, commenting that time-scales of 100 to a million years are not uncommon in geology. Cold weather in the north could affect the surface of the oceans and the winds in another part of the planet that carry rain.
“Rain for us in Egypt originates from two sources, the Atlantic monsoon from the west and the Indian monsoon from the east. These unite into one front named the Intertropical Convergence Zone (ITCZ), which causes rain. If this is directed northwards, it leads to rain, as happened some 11,000 to 8,000 years Before the Present (BP). If it goes southwards, a state of drought occurs. This could be good news for those who fear global warming, as when the sea level rises our desert will become green because there will be more rain,” he said.
Some 150,000 years BP the sea level was low, and the weather in Ethiopia was not as wet as it is today, so it did not feed a lot of water into the Nile. The River Nile looked like a small channel at the time, and the water level in the Mediterranean was 120 metres lower than it is today.
“Approximately 25,000 to 11,000 years BP there was a dry era called the Last Glacial Maximum (LGM), and Egypt went through a drought. In cool weather, the sea level decreases. The Nile flood level was low, and because of the low sea level the Delta had more branches that started to multiply and deepen. These left what are sometimes called ‘turtle backs’ behind them, sediments of soil that people would settle on to be higher than the water level during floods,” Hemdan said.
This period was followed by wet conditions. “From 11,000 to 8,000 years BP, the Nile flood was very high, and the desert also saw a lot of rain, meaning that scientists called it the ‘Green Sahara’ era,” he said, adding that human beings were free to live more widely as a result.
From 10,000 to 8,000 years BP, the land was once again very wet, and the River Nile would increase one cm every year. There was a lot of rain in Ethiopia, and the water in the Nile turned the flood plains into swamps. The river did not deposit much sediment, and it would flood the valley all year round, Hemdan added.
“Some 2,000 years BP is a very important era for the whole planet as it was an ice age that lasted for about 1,000 to 1,500 years, also affecting Egypt,” he said, adding that the Nile at that time consisted of two channels, the main one and one that resembled the Bahr Al- Lebeni and Giza channels that can still be seen today. “We discovered this through satellite images. The first was a short, thin channel near the desert during the Pre-Dynastic Period, and the second one was a large one in the current Nile channel,” he said.... READ MORE.