Old Earth Ministries Online Earth History Curriculum

Presented by Old Earth Ministries (We Believe in an Old Earth...and God!)

This curriculum is presented free of charge for use by homeschooling families.

NOTE:  If you found this page through a search engine, please visit the intro page first. 

 

Chapter 9 - The Triassic Period

Lesson 45: The Tethys Ocean

 

      The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.  About 250 million years ago, during the Triassic, a new ocean began forming in the southern end of the Paleo-Tethys Ocean. A rift formed along the northern continental shelf of Southern Pangaea (Gondwana). Over the next 60 million years, that piece of shelf, known as Cimmeria, traveled north, pushing the floor of the Paleo-Tethys Ocean under the eastern end of Northern Pangaea (Laurasia). The Tethys Ocean formed between Cimmeria and Gondwana, directly over where the Paleo-Tethys used to be.


Chapter 9 - The Triassic Period

 

 Lesson 44 - Triassic Overview

 Lesson 45 - The Tethys Ocean

 Lesson 46 - Supercontinent Pangea

 Lesson 47 - Triassic Species In-Depth, Ichthyosaur

 Lesson 48 - Dinosaurs

 Test 

 

Tethys Ocean map

First phase of the Tethys Ocean's forming: the (first) Tethys Sea starts dividing Pangaea into two supercontinents, Laurasia and Gondwana.

     During the Jurassic Period (150 Ma), Cimmeria finally collided with Laurasia. There it stalled, the ocean floor behind it subducting under, forming the Tethyan Trench. Water levels rose and the western Tethys came to shallowly cover significant portions of Europe, forming the (first) Tethys Sea. Around the same time, Laurasia and Gondwana began drifting apart, opening an extension of the Tethys Sea between them that today is the part of the Atlantic Ocean between the Mediterranean and Caribbean. As North and South America were still attached to the rest of Laurasia and Gondwana, respectively, the Tethys Ocean in its widest extension was part of a continuous oceanic belt running around the Earth between about latitude 30 N and the Equator. Thus, ocean currents at that time around the Early Cretaceous ran radically differently from the way they do today.

     Between the Jurassic and the Late Cretaceous (which started about 100 Ma), Gondwana began breaking up, pushing Africa and India north, across the Tethys and opening up the Indian Ocean. As these land masses pushed in on it from all sides, up until as recently as the Late Miocene (15 Ma), the Tethys ocean continued to shrink, becoming the Tethys Seaway or (second) 'Tethys Sea'.

     Today, India, Indonesia and the Indian Ocean cover the area once occupied by the Tethys Ocean, and Turkey, Iraq, and Tibet sit on Cimmeria. What was once the Tethys Sea has become the Mediterranean Sea. Other remnants are the Black, Caspian and Aral Seas (via a former inland branch known as the Paratethys). Most of the floor of the Tethys Ocean disappeared under Cimmeria and Laurasia. Geologists have found fossils of ocean creatures in rocks in the Himalayas, indicating that those rocks were once underwater, before the Indian continental shelf began pushing upward as it smashed into Cimmeria. We can see similar geologic evidence in the Alpine orogeny of Europe, where the movement of the African plate raised the Alps.

     Paleontologists also find the Tethys Ocean particularly important because much of the world's sea shelves were found around its margins for such an extensive period of time. Marine, marsh-dwelling, and estuarian fossils from these shelves are of considerable paleontological interest.

     Like every science, geology is a continuously evolving system of theories, and the terms used to describe various pre-historic formations have fluctuated as more accurate theories have emerged. For example, many internet sources use "Tethys Ocean" to refer to the "Tethys Sea" and vice versa. Some even appear to erroneously refer to the growing Atlantic Ocean during the Jurassic as the Tethys Sea.
     The western part of the Tethys Ocean is called Tethys Sea, Western Tethys Ocean or Alpine Tethys Ocean. The Black, Caspian and Aral Seas are thought to be its crustal remains (though the Black Sea may in fact be a remnant of the older
Paleo-Tethys Ocean). However, this "Western Tethys" was not simply a single open ocean. It covered many small plates, Cretaceous island arcs and microcontinents. Many small oceanic basins (Valais Ocean, Piemont-Liguria Ocean, Meliata ocean) were separated from each other by continental terranes on the Alboran, Iberian, and Apulian plates. The high sea level in the Mesozoic age flooded most of these continental domains forming shallow seas.
     During the
Oligocene, large parts of central and eastern Europe were covered by a northern branch of the Tethys Ocean, called the Paratethys. The Paratethys was separated from the Tethys by the formation of the Alps, Carpathians, Dinarides, Taurus and Elburz mountains during the Alpine orogeny. It gradually disappeared during the late Miocene, becoming an isolated inland sea.
The eastern part of the Tethys Ocean is likewise sometimes referred to as Eastern Tethys.
     As theories have improved, scientists have extended the "Tethys" name to refer to similar oceans that preceded it. The
Paleo-Tethys Ocean, mentioned above, existed from the Silurian (440 Ma) through the Jurassic eras, between the Hunic terranes and Gondwana (later the Cimmerian terranes). Before that, the Proto-Tethys Ocean existed from the Ediacaran (600 Ma) into the Devonian (360 Ma), and was situated between Baltica and Laurentia to the north and Gondwana to the south. Neither Tethys oceans should be confused with the Rheic Ocean, which existed to the west of them in the Silurian era.


End of Reading

 

Return to the Old Earth Ministries Online Earth History Curriculum homepage.

horizontal rule

Source Page:  Tethys Ocean