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Journal of Creation 37(1):8–9, April 2023

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Ice Age megalakes did exist in the Sahara

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Image: FrankvEck, Wikipedia commons / CC-BY-SA-4.0Lake Chad size comparison with UK 
Figure 1. Lake Chad in 1970 (green) compared with its size during the AHP 7,000 years ago (blue) and the size of the British Isles (red). Lake Chad has shrunk considerably in the last 50 years (yellow area), likely because of increasing demand for water.

Researchers have long known that the Sahara Desert was once wet (or ‘green’1,2). However, there is a question as to when it happened and how wet it became. They believe the Sahara was green very late in the Ice Age and the early Holocene—a period dubbed the African Humid Period (AHP).3 Field research and satellite pictures provide evidence of lakes and rivers that are now mostly buried beneath the sand.4-6 Paleolake Chad covered an area of 340,000 km2,7 much larger than the current Lake Chad (figure 1). Countless fossils from the Ice Age have been found, such as snails, diatoms, ostracodes, fish, foraminifera, elephants, giraffes, buffaloes, antelopes, rhinoceroses, large reptiles, and other animals, including the aquatic hippopotamus.8 This kind of diversity is seen today in the African Serengeti, south of the Sahara Desert. Even dwarf Nile River crocodiles have been found as recently as the early 20th century in isolated lakes or pools in oases of the high western Sahara.9,10 This suggests the Sahara was wet recently. Moreover, many Ice Age artifacts and thousands of rock petroglyphs have been found, suggesting the population of the Sahara was quite large.

Some researchers downplay the wet Sahara

However, some researchers propose there were no megalakes (defined as lake areas greater than 25,000 km2) other than Paleolake Chad, which is fed by rain from the belt of higher precipitation to the south. Instead, they argue there were wetlands and small lakes, suggesting that the wet Sahara may not have been as wet as some suppose.11 Quade et al. suggest that if megalakes existed, it would have required an annual precipitation rate greater than 1.2 m/yr with the Intertropical Convergence zone (ITCZ) displaced greater than 1,000 km north of its current location. Models do not support such a shift of the ITCZ. Because of the models, Quade et al. suggest that the evidence for megalakes can be explained by isolated wetlands and small lakes caused by springs. As proof, they claim that there is a lack of well-developed and spatially extensive shorelines.

At present the ITCZ causes an east–west belt of heavy rain through central Africa. It is known that the precipitation for the green Sahara came from the ITCZ because the oxygen isotope ratios in the water were high.12 Although secular scientists are mystified,13 the green Sahara can be explained within biblical earth history if the Northern Hemisphere ice sheets melted well before the maximum of the Ice Age on Antarctica.1,2 The ITCZ would then have been further north until after glacial maximum in Antarctic 1,000 years after the Flood.

New research vindicates the existence of megalakes

The article by Quade et al. spurred research to re-examine the evidence for Sahara megalakes.14 The researchers not only validated the existence of many megalakes throughout the Sahara, even in the north, they also discovered a new one in the western Sahara, named Lake Timbuktu. They also found many smaller lakes and rivers. Shorelines are not well developed or extensive because moving sand dunes have destroyed most of the geomorphic evidence. The researchers used comprehensive remote sensing of megalake shorelines and their catchments to analyze the megalakes. Sometimes only remnants of shorelines were detected, which showed that high shorelines did exist and proved that megalakes were common and vast. Most of the Sahara basins give evidence of megalakes. Shoreline features cannot be attributed to springs, since springs do not form shorelines.

Timing of megalakes uncertain

Drake et al. realize that the dates of the megalakes are uncertain: “However, it is clear from the literature that the timing of the development of many of these megalakes is poorly constrained.”15 They place the megalakes generally into the uniformitarian Quaternary, 2.6 Ma to 11.7 ka, i.e. their general ice age period. More specifically, they place the existence of megalakes during ‘humid phases’ of the previous interglacial. However, they admit that there is little datable material to substantiate this concretely. The dates used are derived from carbon-14 and U-series techniques used on fossils shells, but these methods are said to be notoriously unreliable for dating fossil shells. Although luminescence techniques could potentially date quartz-rich sand shorelines, it has been applied only in a few locations.

Researchers still do not know origin of wet Sahara

In regard to the needed precipitation to fill up the paleolakes, Drake et al. admit that the models fail. They try to justify the existence of many megalakes by claiming that many catchments contain mountains, and that more precipitation is expected in the mountains, which is true. However, today the Sahara has mountains and basins, but the Sahara is very far from producing megalakes, with the exception of Lake Chad. Although Drake et al. show that the existence of megalakes is robust, they skirt around the ‘elephant in the room’: why was there much more precipitation than there is today?

The Ice Age solution

The biblical rapid Ice Age model can explain the existence of the large and small lakes in the Sahara and the population of animals and people by a northward displacement of the ITCZ.1,2 In the same way as were the lakes in the southwestern U.S., and other lakes generally around the 30th parallel of the Northern Hemisphere, the Saharan lakes were first filled during Flood runoff. Residual floodwater would have been left in enclosed basins. Evidence for this could be the marine foraminifera fossils found in the Sahara Desert. Then much more rain in the Sahara during the Ice Age would have either maintained the lakes or filled them up to overflowing, resulting in rivers and streams. Dried-up rivers and streams with amphibian fossils are found below the sand. Such a wet environment was caused by much greater evaporation from the Ice Age warm ocean and a different general circulation from that evident today. But the wet Sahara continued after the Ice Age into the mid Holocene, likely because the ITCZ was displaced much farther north.

Conclusion

The notion of a ‘wet Sahara’ in the recent past is controversial among secular researchers, since they struggle to adduce a mechanism to explain it. However, much evidence exists for it and has recently been bolstered through the discovery of ancient shorelines. And unlike the conditions proposed by secular researchers, the conditions produced by a post-Flood Ice Age in the biblical perspective provide mechanisms for explaining the existence of a ‘wet Sahara’.

Posted on homepage: 17 May 2024

References and notes

  1. Oard, M.J., Ice core oscillations and abrupt climate changes: part 5—the early Holocene green Sahara, J. Creation 35(3):103–108, 2021. Return to text.
  2. Oard, M., The lush green Sahara, Creation 42(3), p. 45–47, 2020. Return to text.
  3. Ménot, G., Pivot, S., Bouloubassi, I., Davtian, N., Hennekam, R., Bosch, D., Ducassou, E., Bard, E., Migeon, S., and Revel, M., Timing and stepwise transitions of the African Humid Period from geochemical proxies in the Nile deepsea fan sediments, Quaternary Science Reviews 228(106071):1–14, 2020. Return to text.
  4. Pachur, H.-J. and Kröpelin, S., Wadi Howar: paleoclimatic evidence from an extinct river system in the southeastern Sahara, Science 237:298–300, 1987. Return to text.
  5. Chorowicz, J. and Fabre, J., organization of drainage networks from space imagery in the Tanezrouft plateau (Western Sahara): implications for recent intracratonic deformations, Geomorphology 21:139–151, 1997. Return to text.
  6. Paillou et al., Mapping of the major paleodrainage system in eastern Libya using orbital imaging radar: the Kufrah River, Earth and Planetary Science Letters 277:327–333, 2009. Return to text.
  7. Hoelzmann, P., Kruse, H.-J., and Rottinger, F., Precipitation estimates for the eastern Saharan palaeomonsoon based on a water balance model of the West Nubian palaeolake basin, Global and Planetary Change 26:105–120, 2000. Return to text.
  8. Kröpelin, S. and Soulié-Märsche, I., Charophyte remains from Wadi Howar as evidence for deep mid-Holocene freshwater lakes in the eastern Sahara of Northwest Sudan, Quaternary Research 36:210–223, 1991. Return to text.
  9. Charlesworth, J.K., The Quaternary Era, Edward Arnold, London, p. 1113, 1957. Return to text.
  10. Drake, N.A., Blench, R.M., Armitage, S.J., Bristow, C.S., and White, K.H., Ancient watercourses and biogeography of the Sahara explain the peopling of the desert, PNAS 108(2):458–462, 2011. Return to text.
  11. Quade, J., Dente, E., Armon, M., Ben Dor, Y., Morin, E., Adam, O., and Enzel, Y., Megalakes in the Sahara? A review, Quaternary Research 90:253–275, 2018. Return to text.
  12. Hoelzmann, P., Kruse, H.-J., and Rottinger, F., Precipitation estimates for the eastern Saharan palaeomonsoon based on a water balance model of the West Nubian Palaeolake Basin, Global and Planetary Change 26:103–120, 2000. Return to text.
  13. Notaro, M., Wang, Y., Liu, Z., Gallimore, R., and Levis, S., Combined statistical and dynamical assessment of simulated vegetation–rainfall interactions in North Africa during the mid- Holocene, Global Change Biology 14:347–368, 2008. Return to text.
  14. Drake, N.A., Candy, I., Breeze, P., Armitage, S.J., Gasmi, N., Schwenninger, J.L., Peat, D., and Manning, K., Sedimentary and geomorphic evidence of Saharan megalakes: a synthesis, Quaternary Science Reviews 276:1–20, 2022 ǀ doi.org/10.1016/j.quascirev.2021.107318. Return to text.
  15. Drake et al., ref. 14, p. 17. Return to text.

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