Did increased flooding during the African Humid Period force migration of modern humans from the Nile Valley?

Zaki, Abdallah S.; King, Georgina E.; Haghipour, Negar; Giegengack, Robert; Watkins, Stephen E.; Gupta, Sanjeev; Schuster, Mathieu; Khairy, Hossam; Ahmed, Salah; El-Wakil, Mostafa; Eltayeb, Saleh A.; Herman, Frédéric; Castelltort, Sébastien

doi:10.1016/j.quascirev.2021.107200

Cited by 21 publications

(26 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our estimates from the width‐based discharge fall in the range of 33–245 m 3 /s. These estimates differ from discharge quantified from grain‐size distribution and paleochannel channel geometry (43–138 m 3 /s; Zaki, King, et al., 2021 ). When comparing the two values quantified from the two methods, the width‐discharge relationship yields a factor of ∼70% higher than the discharge estimated from the grain size and slope reconstruction.…”

Section: Discussionmentioning

confidence: 78%

“…These estimates are minimum rates and volumes, as the reconstruction of the precise elevation of the former eroded surface is not possible with the fluvial ridges. In order to constrain a reasonable age for the regional aridification that represents the onset of processes that lowered the surface, we evaluated ages determined from different proxies, including fluvial ridges, pollen records, dust fluxes, lake levels, lake sediments, and human occupation (e.g., Kuper & Kropelin, 2006 ; Nicoll, 2004 ; Zaki, King, et al., 2021 ). We find that the recent aridification started at ∼5 ka BP.…”

Section: Resultsmentioning

confidence: 99%

“…Zaki, King, et al. ( 2021 ) focused on obtaining absolute ages using OSL and 14 C, and reconstructing precipitation rates involved in forming the upstream paleochannels of these fluvial systems based on grain size. However, investigating the morphology and the drainage areas from the source to sink systems, the internal architecture of the whole ridge, reconstructing discharge using channel width, and calculating the inversion rates remain unconstrained.…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, Zaki, King, et al. ( 2021 ) recently dated these paleo‐rivers using OSL and 14 C; their results indicate that they were formed by several depositional events ranging from 53 ka to 1 ka. The ages indicate intense fluvial activity during the early (∼13,000 BP) to middle (∼5,200 BP) Holocene driven by heavy rainfall events (Zaki, King, et al., 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…The ages indicate intense fluvial activity during the early (∼13,000 BP) to middle (∼5,200 BP) Holocene driven by heavy rainfall events (Zaki, King, et al., 2021 ). The intensity of rainfall events was briefly calculated using grain size and paleo‐channel geometry to obtain the discharge, then dividing the discharge by drainage area leads to minimum precipitation rates (Zaki, King, et al., 2021 ). This intense episode of humid conditions has been linked to the African Humid Period ‐ AHP (ca.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

et al. 2022

View full text Add to dashboard Cite

A widely hypothesized but complex transition from widespread fluvial activity to predominantly aeolian processes is inferred on Mars based on remote sensing data observations of ancient landforms. However, the lack of analysis of in situ martian fluvial deposits hinders our understanding of the flow regime nature and sustainability of the martian fluvial activity and the hunt for ancient life. Studying analogs from arid zones on Earth is fundamental to quantitatively understanding geomorphic processes and climate drivers that might have dominated during early Mars. Here we investigate the formation and preservation of fluvial depositional systems in the eastern Sahara, where the largest arid region on Earth hosts important repositories of past climatic changes. The fluvial systems are composed of well-preserved single-thread sinuous to branching ridges and fan-shaped deposits interpreted as deltas. The systems' configuration and sedimentary content suggest that ephemeral rivers carved these landforms by sequential intermittent episodes of erosion and deposition active for 10-100s years over ∼10,000 years during the late Quaternary. Subsequently, these landforms were sculpted by a marginal role of rainfall and aeolian processes with minimum erosion rates of 1.1 ± 0.2 mm/yr, supplying ∼96 ± 24 × 10 10 m 3 of disaggregated sediment to adjacent aeolian dunes. Our results imply that similar martian fluvial systems preserving single-thread, short distance source-to-sink courses may have formed due to transient drainage networks active over short durations. Altogether, this study adds to the growing recognition of the complexity of interpreting climate history from orbital images of landforms.Plain Language Summary Mars is currently a dry and cold desert, but rivers preserved in inverted topography suggest that water once flowed during its early history. However, how sustained and how frequently these rivers flowed remains uncertain. Here we study ancient fluvial systems (rivers and deltas) from the eastern Sahara that formed during the late Quaternary, in much wetter conditions than those prevailing today in this desert and which bear striking analogies to martian systems. We find that rivers and deltas, now preserved as ridges, record short distance source-to-sink high-energy systems formed due to heavy rainfall events. Our observations and measurements of the meandering systems within the deltaic features suggest that such wet conditions might have spanned tens to a few hundred years over a total duration of ∼10,000 years. Since the wet conditions ceased, arid conditions prevailed, and the aeolian processes resumed, sculpting ridges out of ancient channels. Our results imply that martian fluvial systems may have been associated with similar local and heavy runoff conditions that lasted 10-100s years over thousands of years, possibly sufficient to support habitability. A shift toward arid environments led to the sculpting of fluvial ridges and the widespread formation of dunes across the modern martian landscape.

show abstract

Section: Discussionmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

et al. 2022

View full text Add to dashboard Cite

show abstract

The Origins of War

Meijer

2024

Hum Nat

View full text Add to dashboard Cite

Geochemistry and mineralogy of modern floodplain Nile sediments of Sohag area, Egypt: an environmental perspective

Ali,

Aal,

Radwan

et al. 2024

Environ Earth Sci

View full text Add to dashboard Cite

Understanding the characteristics of modern floodplain sediment (MFS) is important for geomorphological, paleoclimatic, sedimentation, and environmental investigations. We collected samples from present floodplain Nile sediments in Egypt’s Sohag area and used mineralogical and geochemical (i.e., major and trace elements) proxies to investigate the characteristics and establish their provenances, climatic conditions during deposition, and weathering influence. The study revealed that the Nile floodplain sediments are composed mainly of silt (26–77%), clay fraction (7–44%), and sand content (3–63%), and their texture is classified as clayey silt. These sediments are classified geochemically as greywacke to shale. The mineralogical studies revealed two main assemblages of heavy minerals: the first assemblage represented by magnetite, goethite, zircon, epidote, and garnet and reflects the basement complex in the Eastern Desert and its surrounding rocks; and the second assemblage of goethite, pyroxene, hornblend, and mica of fooldplain deposits derived from the Ethiopian highlands. The geochemical studies indicate that the Nile sediments are immature and formed due to the moderate degree and nonsteady chemical weathering of the parent rocks. The geochemical studies show different mixed sources of sediments, where fine sediments are mostly mafic igneous with a partial contribution from siliscic sedimentary rocks, while the coarser ones are derived mainly from siliscic sedimentary and acidic igneous rocks. The sediments of the presented modern fooldplain reflected two different tectonic setting source areas (collision and continental rift tectonic setting for high silica and low silica samples, respectively) that were shared in supplying the sediments to the present basin. The study revealed that the investigated area may become desertified as a result of climate change and human activities such as salinity, fertiliser use, sand encroachment, and pollution.

show abstract

Did increased flooding during the African Humid Period force migration of modern humans from the Nile Valley?

Cited by 21 publications

References 62 publications

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

Fluvial Depositional Systems of the African Humid Period: An Analog for an Early, Wet Mars in the Eastern Sahara

The Origins of War

Geochemistry and mineralogy of modern floodplain Nile sediments of Sohag area, Egypt: an environmental perspective

Contact Info

Product

Resources

About