Tethys Ocean
Prehistoric ocean that fragmented into the Indian Ocean and Mediterranean.
Wikipedia / Wikimedia Commons
The Tethys Ocean (pronounced TEETH-iss or TETH-), also known as the Tethys Sea or Neo-Tethys, was a prehistoric body of water that existed through much of the Mesozoic Era and into the early to middle Cenozoic Era. It gave rise to the modern Indian Ocean, the Mediterranean Sea, and the inland marine basins of Eurasia—chiefly the Black Sea and Caspian Sea today. In the early Mesozoic, as the supercontinent Pangaea split apart, the term "Tethys Ocean" described the sea lying between the ancient landmasses of Gondwana and Laurasia. Later, after the Indian and Atlantic oceans opened during the Cretaceous and those continents further fragmented, the Tethys referred to the ocean bordered by Africa, Eurasia, India, and Australasia.
During the early to middle Cenozoic, the Indian, African, Australian, and Arabian tectonic plates moved northward and collided with the Eurasian plate. This created new boundaries for the ocean, formed a land barrier that blocked currents between the Indian and Mediterranean basins, and triggered the mountain-building events of the Alpide belt—including the Alps, Himalayas, Zagros, and Caucasus ranges. These geological shifts, combined with a drop in sea level due to Antarctic glaciation, ended the Tethys as it had existed, splitting it into the Indian Ocean, the Mediterranean Sea, and a separate basin called the Paratethys.
The Tethys was preceded by the Paleo-Tethys Ocean, which lasted from the Cambrian to the Early Triassic. The Neotethys itself formed during the Late Triassic and persisted in some form until the Oligocene–Miocene boundary, roughly 24 to 21 million years ago, when it fully closed. A portion known as the Paratethys became isolated during the Oligocene (about 34 million years ago) and survived until the Pliocene (around 5 million years ago), when it largely dried up. The modern inland seas of Europe and Western Asia—the Black Sea and Caspian Sea—are remnants of this Paratethys Sea.
The ocean takes its name from Tethys, a water goddess in ancient Greek mythology who was sister and consort to Oceanus, and mother of the Oceanid sea nymphs as well as the world's great rivers, lakes, and fountains.
In terms of terminology and subdivisions, the eastern part of the Tethys is sometimes called Eastern Tethys, while the western part is referred to as the Tethys Sea, Western Tethys Ocean, Paratethys, or Alpine Tethys Ocean. Th
- Existed
- Mesozoic Era through early-mid Cenozoic Era
- Preceded by
- Paleo-Tethys Ocean (Cambrian–Early Triassic)
- Succeeded by
- Indian Ocean, Mediterranean Sea, Paratethys
- Named after
- Tethys, Greek water goddess
- Key geological events
- Collision of African, Indian, Australian, Arabian plates with Eurasian plate; Alpide belt orogenies; Antarctic glaciation sea-level drop
Lore & Background
The Tethys Ocean formed during the Late Triassic, after the Paleo-Tethys Ocean, and lasted in some form up to the Oligocene–Miocene boundary (about 24–21 million years ago) when it completely closed. A portion known as the Paratethys was isolated during the Oligocene (34 million years ago) and lasted up to the Pliocene (about 5 million years ago), when it largely dried out. The modern inland seas of Europe and Western Asia, namely the Black Sea and Caspian Sea, are remnants of the Paratethys Sea. During the early Mesozoic, as Pangaea broke up, the Tethys Ocean lay between Gondwana and Laurasia. Later, after the Cretaceous, it was bordered by Africa, Eurasia, India, and Australasia.
Reader's Guide
The Tethys Ocean is significant as the direct predecessor to the Indian Ocean, the Mediterranean Sea, and the Eurasian inland marine basins (Black Sea and Caspian Sea). Its closure during the early-mid Cenozoic, driven by the northward collision of the Indian, African, Australian, and Arabian plates with Eurasia, created the Alpide belt mountains (Alps, Himalayas, Zagros, Caucasus) and a land barrier that altered global ocean currents. This decoupling, combined with Antarctic glaciation sea-level drop, fragmented the Tethys. The complete closure around 20 and 14 million years ago led to a global reorganization of currents, enabling upwelling in the Arabian Sea and establishing the modern South Asian Monsoon. The Tethys also hosted diverse marine life during the Late Cretaceous, including large mosasaurs and pterosaurs like Hatzegopteryx, and its islands produced examples of insular dwarfism and gigantism among dinosaurs and pterosaurs.
Did You Know?
- The Tethys Ocean is named after Tethys, a Greek water goddess, sister and consort of Oceanus.
- The Paratethys, a northern branch of the Tethys, was isolated during the Oligocene and largely dried out by the Pliocene.
- During the Late Cretaceous, the Tethys Sea was home to large mosasaurs such as Prognathodon giganteus and Mosasaurus hoffmannii.
- The Tethys Ocean's closure helped establish the modern South Asian Monsoon.
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