Dylan Seaton
10 000 years ago, the Saharan Desert was unlike what we see today. Back then, these dry lands were once lush with dense vegetation, rivers and lakes.
Simply put, Earth goes through cyclical variations due to its orbit around the sun. These variations are called Milankovitch Cycles. The first cycle, the Eccentricity, is the change in Earth’s orbital shape around the sun, occurring every ±100 000 years. The second, the Obliquity, is the change in the angle of Earth’s tilt on its axis, every ±41 000 years. The third is the Precession, aka. The Wobble, which is precisely what happens as the Earth rotates on its axis. The Wobble occurs every ±26 000 years and has major implications on climate variabilities between the Northern and Southern Hemispheres. And it is this cycle that caused the ‘Greening’ of the Saharan Desert.
For some epic animations and more details describing these cycles click here.
The Precession 'reinforced’ the African monsoons, generating heavy rains and bringing about the African Humid Period. This period lasted around 9 000 years, until ±5 000 years ago. Remnants of the old environment are still visible today.
My study is looking at some of these landscape remnants that formed during the African Humid Period. Specifically, my research is studying landforms called Alluvial Fans.
Alluvial fans are cone-shaped sediment deposits that develop along mountain fronts or steep valleys, where narrow river channels suddenly open up to wide, flat plains (Figure 1). These sediment deposits hold information of when and how water flowed here.
I am looking at the physical and chemical properties of the sediments in alluvial fans to paint a clearer picture of the African Humid Period, particularly in Morocco.
This blog, however, will not delve into the sciences, but rather share my first experience in the Anti-Altas Mountains of Morocco.
Landing in the late morning of Agadir, my supervisors and I were welcomed by a geological professor from University Ibn Zohr, who would be our guide for the next week.
After some refreshments, we made our way some 200 km south to Guelmim. After arriving, we took the opportunity to stretch our legs and wander around the local area.
The following day we left for Assa, stopping along the way to learn about the evolution of the Anti-Atlas Mountains.
The next few days saw us trekking, surveying, taking measurements and hammering the rocks for sampling.
We also took some time to observe things that weren’t only geology. Despite being a desert, Assa still hosts an abundance of life, from scant lizards to large dromedaries.
Dromedary roaming the morning desert.
The last day saw us frantically packing our bags for the +300 km drive back to Agadir. Taking a slight detour, we visited other sites and investigated the results of the September-October 2024 floods.
Despite a little flu, and aching hands from the hammering, the trip was a major success. I got more context for my project, met some amazing people and experienced a new, yet familiar culture. With heaps of data collected, ready to be analyzed, my piece of the puzzle is finding its way to the bigger picture of the African Humid Period. I look forward to my next trip.
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