At the secondary era, in the middle of the cretaceous (100 million years), the Arabic plate is detached from Africa and converges towards Asia. Its Eastern edge then will start a process of depression (subduction) under the oceanic floor which separated them.

When this subduction blocked (80 million years) the Omani continental terrace started to be raised, with on its back the scrap of the oceanic floor under which it had passed. Exposed thus, this oceanic floor or “ophiolite” made it possible to the geologists of the whole world to study it and to better know the constitution of the current oceanic funds.

The site “Geotimes” (see photo) located at the border with the Emirates corresponds to the summit part of this ophiolite, where one can observe spectacular lava in the shapes of cushions (famous pillow lavas of the geologists) testifying to volcanic overflowings to great depths under the sea (- 4000 meters).  

Wadi Al Abyad makes it possible to visualize the base of this oceanic scrap where one can touch the limit between the oceanic crust and the coat; this contact is known under the name of Moho by the geologists. To observe this limit, usually located at 10 kilometers of depth under the surface of the Earth, is an exceptional case in the world.

Djebel Akhdar, climax of Oman, makes it possible to see the sediments limestones and argillaceous Omani Arabic margin. These sediments were folded and deformed during their hiding under the oceanic floor.  Djebel Bani , as for him, consists of limestones of the tertiary era (60 million years) rich in fossils in the shapes of small coins of currency called “nummulites”. They settled on the ophiolite after the first rising followed by strong erosion, which made it possible the sea to make this last incursion before rising general of all the unit describes above, which constitutes the Omanaise mountain today.

                                                                                       Pillows Lavas, site                           Snake Canyon, calc  of
                                                                                            Geotimes                                            Djebel Akhdar

Centre de Géologie de l’Oisans, 38520 Bourg d’Oisans, France
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