Lake Ptolemy
Lake Ptolemy | ||
---|---|---|
West Nubian Paleolake, Northern Darfur Megalake | ||
Primary inflows ? | | |
River sources | ? | |
Primary outflows | ? | |
Basin countries | Sudan | |
Surface area | 8,133–11,230 km2 (3,140–4,336 sq mi) | |
Max. depth | 15 m (49 ft) | |
Water volume | 372–547 km3 (89–131 cu mi) | |
Salinity | ? | |
Surface elevation | 550–555 m (1,804–1,821 ft) | |
Max. temperature | ? | |
Min. temperature | ? | |
Frozen | Never | |
Islands | ? |
Lake Ptolemy is a former lake in
Name and research history
The lake's deposits were first recognized in 1985-1986, but the "chelonide marshes" or "turtle swamp" of Ptolemy almost certainly refer to the former lake.[1] It is also known as "West Nubian lake",[2] "West Nubian Paleolake" and "Northern Darfur Megalake".[3] "Ptolemy lake archipelago" refers to dune fields that were periodically submerged along the eastern shores, forming archipelagos.[4] The lake name was first mentioned in a 1858 map, but its existence became clear only in 1980–1982.[5]
Geomorphology
Context
During the early and middle
Lake
Lake Ptolemy is located on the territory of present-day Sudan.[9] Estimates of its size have changed as the quality of regional maps changed: At first, it was believed to have reached surface areas of about 27,000 square kilometres (10,000 sq mi);[10] later research on the basis of more reliable elevation maps suggested that it was no larger than 5,330 square kilometres (2,060 sq mi);[11] later still, newer maps indicated larger surface areas of 8,133 square kilometres (3,140 sq mi) and 11,230 square kilometres (4,340 sq mi) and a volume of 372 cubic kilometres (89 cu mi) and 547 cubic kilometres (131 cu mi), respectively.[12]
Depending on the location, evidence for water levels of 550 metres (1,800 ft) or even 555 metres (1,821 ft) above sea level have been found;[13] in the former case the lake may have occupied an area of no less than 17,864 square kilometres (6,897 sq mi).[14] There is also evidence of shorelines at altitudes of 570–576 metres (1,870–1,890 ft) above sea level;[15] if they reflect the lake reaching that altitude, this stand would reach a surface of 30,750 square kilometres (11,870 sq mi) and a volume of 2,530 cubic kilometres (610 cu mi) at that stage.[12] Such a size is comparable to Canada's largest lake, the Great Bear Lake,[16] and larger than Lake Erie. It would have been up to 83 metres (272 ft) deep.[17] Lower lake stages might have reached 565 metres (1,854 ft) and 560 metres (1,840 ft) elevation,[18] and there is fossil evidence that episodes of shallow water level occurred in the lake.[19] The lake floor in its southern and western sectors reaches 549 metres (1,801 ft) elevation above sea level.[20]
The lake existed in the area of present-day
Hydrology
The lake was nourished by runoff from the
This runoff reached the lake through various wadis,
The presence of
At a water level of 550 metres (1,800 ft) Lake Ptolemy would have been connected with a paleodrainage system belonging to the Abyad Plateau.[39] A connection between Lake Ptolemy and Wadi Howar which drains to the Nile is possible.[4][40] but not proven.[41] At water levels of 577–583 metres (1,893–1,913 ft) Lake Ptolemy would overflow into Wadi Arid.[18]
Biology
Lake Ptolemy featured a diverse ecosystem,[41] especially in its southwestern sector where tributaries formed river deltas with diverse environments; these include banks, reed beds, shallow lakes and swamps.[42] Plant species documented from Lake Ptolemy include Acacia and Tamarix species, as well as Balanitos aegyptiaca and Capparis decidua.[26] The various water systems aided in the propagation of plants.[43] Reed vegetation formed on the southern and western shores of the lake,[24] and probably extended over its entire perimeter and sometimes into open water.[5] The existence of Typha suggests that shallow lake phases occurred.[21] Microbialites[44] and stromatolites also formed on the lake shores and together with limnites are used to delimit the lake surface.[45]
About 10-18
The south shore of Lake Ptolemy could have been inhabited by neolithic pastoralists,[47] while the swampy conditions at the northern margin rendered it presumably inhospitable.[48] In addition, many human artifacts have been found in the region surrounding the former lake,[49] some of which may have had religious-spiritual significance.[42] As the lake levels decreased, populations migrated deeper into the lake basin.[50]
Lake chronology
The lake basin was probably formed before the
Lake Ptolemy existed as a freshwater lake already around 9,180 ± 185 years before present.
Wadis flowing into the lake were transporting water as late as 3,300 – 2,900 and 3,300 – 2,400 years before present on the southern and northern side, respectively. During its drying, the lake split into separate pools.
Relationship to groundwater and ecosystems
Lake Ptolemy is related to the Nubian Sandstone Aquifer; in simulations maximum water levels in the aquifer reached the surface of the lake,[57] and about 3 cubic kilometres (0.72 cu mi) of water from the lake entered the aquifer every year.[58] The lake further aided in the interchange between Lake Chad and Nile species.[6]
See also
- African humid period – Holocene climate period during which northern Africa was wetter than today
References
- ^ Kropelin 2009, pp. 167–168.
- ^ a b c d Pachur & Altmann 2006, p. 205.
- ^ a b Elsheikh, Abdelsalam & Mickus 2011, p. 82.
- ^ a b Pachur & Altmann 2006, p. 219.
- ^ a b c d e f Pachur 1997, p. 229.
- ^ a b c Pachur & Altmann 2006, p. 35.
- ^ a b c Pachur 1997, p. 228.
- ^ Hoelzmann et al. 2001, p. 193.
- ^ a b Gossel, Ebraheem & Wycisk 2004, p. 705.
- ^ Pachur & Altmann 2006, p. 226.
- ^ Hoelzmann et al. 2001, p. 213.
- ^ a b Elsheikh, Abdelsalam & Mickus 2011, p. 83.
- ^ Pachur & Altmann 2006, p. 221.
- ^ Pachur 1997, p. 240.
- ^ Ghoneim & El-Baz 2007, pp. 5008, 5009.
- ^ Ghoneim & El-Baz 2007, p. 5001.
- ^ Ghoneim & El-Baz 2007, p. 5013.
- ^ a b Ghoneim & El-Baz 2007, p. 5014.
- ^ a b Pachur 1997, p. 231.
- ^ a b Pachur & Altmann 2006, p. 216.
- ^ a b c d e Pachur & Altmann 2006, p. 207.
- ^ Pachur 1997, p. 238.
- ^ Quade et al. 2018, pp. 9–11.
- ^ a b Pachur & Altmann 2006, p. 212.
- ^ Ghoneim & El-Baz 2007, p. 5010.
- ^ a b c d Pachur & Altmann 2006, p. 206.
- ^ a b Pachur 1997, p. 230.
- ^ a b Pachur & Altmann 2006, p. 36.
- ^ Hoelzmann et al. 2001, p. 214.
- ^ Ghoneim & El-Baz 2007, p. 5005.
- ^ a b c Pachur & Altmann 2006, p. 208.
- ^ Pachur 1997, p. 239.
- ^ Pachur & Altmann 2006, p. 230.
- ^ Kropelin 2009, p. 168.
- ^ Elsheikh, Abdelsalam & Mickus 2011, p. 84.
- ^ a b Pachur 1997, p. 235.
- ^ a b Pachur & Altmann 2006, p. 465.
- ^ Pachur & Altmann 2006, p. 222.
- ^ Pachur & Altmann 2006, p. 236.
- ^ Pachur 1997, p. 233.
- ^ a b Pachur & Altmann 2006, p. 218.
- ^ a b Pachur 1997, p. 234.
- ^ Pachur & Altmann 2006, p. 224.
- ^ Pachur 1997, p. 236.
- ^ Pachur & Altmann 2006, p. 220.
- ^ a b c d Pachur & Altmann 2006, p. 228.
- ^ Pachur & Altmann 2006, p. 44.
- ^ Kropelin 2009, p. 169.
- ^ Pachur & Altmann 2006, p. 231.
- ^ Kropelin 2009, p. 170.
- ^ Pachur & Altmann 2006, p. 294.
- ^ Pachur & Altmann 2006, pp. 223, 224.
- ^ Pachur & Altmann 2006, pp. 227, 228.
- ^ a b Pachur & Altmann 2006, p. 209.
- ^ a b Pachur & Altmann 2006, p. 210.
- ^ Pachur & Altmann 2006, p. 468.
- ^ Gossel, Ebraheem & Wycisk 2004, p. 708.
- ^ Pachur & Altmann 2006, p. 229.
Bibliography
- Elsheikh, Ahmed; Abdelsalam, Mohamed G.; Mickus, Kevin (1 August 2011). "Geology and geophysics of the West Nubian Paleolake and the Northern Darfur Megalake (WNPL–NDML): Implication for groundwater resources in Darfur, northwestern Sudan". Journal of African Earth Sciences. 61 (1): 82–93. .
- Ghoneim, E.; El-Baz, F. (20 November 2007). "DEM-optical-radar data integration for palaeohydrological mapping in the northern Darfur, Sudan: implication for groundwater exploration". International Journal of Remote Sensing. 28 (22): 5001–5018. S2CID 88510033.
- Gossel, W.; Ebraheem, A. M.; Wycisk, P. (1 December 2004). "A very large scale GIS-based groundwater flow model for the Nubian sandstone aquifer in Eastern Sahara (Egypt, northern Sudan and eastern Libya)". Hydrogeology Journal. 12 (6): 698–713. S2CID 128894657.
- Hoelzmann, Philipp; Keding, Birgit; Berke, Hubert; Kröpelin, Stefan; Kruse, Hans-Joachim (15 May 2001). "Environmental change and archaeology: lake evolution and human occupation in the Eastern Sahara during the Holocene". Palaeogeography, Palaeoclimatology, Palaeoecology. 169 (3–4): 193–217. .
- Kropelin, S (2009). "Holozäne Umweltrekonstruktion und Kulturgeschichte der Sahara: Perspektiven aus der sudanesischen Wüste" (PDF). Nova Acta Leopoldina (in German). 108: 165–191.
- Pachur, Hans-Joachim (April 1997). "Der Ptolemäus-See in Westnubien als Paläoklimaindikator". Petermanns Geographische Mitteilungen (in German) (141): 227–250.
- Pachur, Hans-Joachim; Altmann, Norbert (2006). Die Ostsahara im Spätquartär (in German). Springer Berlin Heidelberg. ISBN 978-3-540-47625-2.
- Quade, J.; Dente, E.; Armon, M.; Dor, Y. Ben; Morin, E.; Adam, O.; Enzel, Y. (2018). "Megalakes in the Sahara? A Review". Quaternary Research. 90 (2): 9–11. ISSN 0033-5894.