Temporal Distribution
There have been five known ice ages in the Earth's history; the Earth is experiencing the Quaternary Ice Age during the present time. Tunnel valleys formed during four of the five have been identified.
| Name | Period (Ma) | Period | Era | Tunnel valleys and tunnel valley formation extensively observed |
|---|---|---|---|---|
| Quaternary | 2.58 - Present | Neogene | Cenozoic | Tunnel valleys formation has been reported in northern Asia, Europe, North America, and Antarctica |
| Karoo | 360 - 260 | Carboniferous and Permian | Paleozoic | Tunnel valleys has been reported in the Carboniferous–Permian glacial record of Australia and of South Africa. |
| Andean-Saharan | 450 - 420 | Ordovician and Silurian | Paleozoic | Tunnel valleys have been reported in Jordan, Saudi Arabia, Mauritania, Mali, Morocco, Algeria, Libya, Tunisia, Niger, Chad, and Sudan. |
| Cryogenian (or Sturtian-Varangian) |
800 - 635 | Cryogenian | Neoproterozoic | Tunnel valleys have been reported in the Cryogenian strata of Oman and Mauritania. |
| Huronian | 2100–2400 | Siderian and Rhyacian | Paleoproterozoic |
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“Death is not an event in life: we do not live to experience death. If we take eternity to mean not infinite temporal duration but timelessness, then eternal life belongs to those who live in the present.”
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