Evidence for Past Glaciations
- Autor(en)
- Jean François Ghienne, Daniel P. Le Heron
- Abstrakt
On three occasions, during the Cryogenian, Ordovician and early Carboniferous, the present-day Sahara was glaciated. The first of these glaciations left glacial landforms and deposits in the western part of the desert. Much more widely, expansion of large ice masses towards the present north took place multiple times during the late Ordovician and led to the development of spectacular sediment–landform assemblages (found in Mali, Mauritania, Morocco, Algeria, Libya, Niger, Benin and Chad) that allow for ice sheet dynamics to be reconstructed. Striated surfaces are widespread and are only one example of linear features developed beneath the ice: highly attenuated and elongate mega-scale glacial lineations, produced by fast-flowing ice streams, occur in multiple localities. Irregular, mounded piles of sediments associated with this glaciation may represent ice stagnation landforms, and circular-outlined phenomena such as pingos occurred beyond the ice front. Meltwater-related features include ice-marginal tunnel valleys and proglacial channel networks. The early Carboniferous record is recognised in Niger, Chad and south-western Egypt.
- Organisation(en)
- Institut für Geologie
- Externe Organisation(en)
- Université de Strasbourg
- Seiten
- 23-31
- Anzahl der Seiten
- 9
- DOI
- https://doi.org/10.1007/978-3-031-47160-5_3
- Publikationsdatum
- 2023
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105101 Allgemeine Geologie
- Schlagwörter
- ASJC Scopus Sachgebiete
- Geology, Earth-Surface Processes
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/59139293-3d23-4508-b547-303e288f789c