The Mascarene Plateau is an submarine plateau

Oceanic plateau

An oceanic plateau is a large, relatively flat submarine region that rises well above the level of the ambient seabed. While many oceanic plateaus are composed of continental crust, and often form a step interrupting the continental slope, some plateaus are undersea remnants of large igneous...

 in the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

, north and east of Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

. The plateau extends approximately 2000 km, from the Seychelles

Seychelles

Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

 in the north to Réunion

Réunion

Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...

 in the south. The plateau covers an area of over 115,000 km² of shallow water, with depths ranging from 8150 meters, plunging to 4000 meters to the abyssal plain

Abyssal plain

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest...

 at its edges. It is the largest undersea plateau in the Indian Ocean.

Geography

The northern part of the Mascarene plateau includes the Seychelles

Seychelles

Seychelles , officially the Republic of Seychelles , is an island country spanning an archipelago of 115 islands in the Indian Ocean, some east of mainland Africa, northeast of the island of Madagascar....

 and Agalega Islands

Agalega Islands

The Agalega Islands are two islands in the Indian Ocean, lying north of Mauritius at and are governed by that country. The islands have a total area of 24 km² , although the official figure of 70 km² appears too high when compared with data from satellite images.The North Island is home...

. The southern part of the Mascarene plateau includes the Mascarene Islands

Mascarene Islands

The Mascarene Islands is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks...

, Saya de Malha Bank

Saya de Malha Bank

The Saya de Malha Bank is the largest submerged bank in the World, part of the vast undersea Mascarene Plateau...

, Nazareth Bank

Nazareth Bank

Nazareth Bank is a large submerged bank in the Indian Ocean. It lies about 1040 km east of northern Madagascar and 280 km south of Saya de Malha Bank. The closest land is Cargados Carajos shoals, a small and remote dependency of Mauritius located 140 km to the southwest. The Nazareth...

, Soudan Banks

Soudan Banks

The Soudan Banks are a group of underwater high points and reefs off the coast of Africa, known for their good fishing and administered by Mauritius. The five banks lie on the Mascarene plateau. North Soudan contains large salmon stocks. South Soudan is the largest of the banks, with many reefs...

, and Hawkins Bank

Hawkins Bank

Hawkins Bank is a large, submerged bank off the Mascarene Plateau. It is considered a dependency of Mauritius The bank is abundant with fish and Mauritian vessels often fish in the waters in and around the bank....

. The Mascarene Islands are the mountainous islands of Mauritius

Mauritius

Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...

, Réunion

Réunion

Réunion is a French island with a population of about 800,000 located in the Indian Ocean, east of Madagascar, about south west of Mauritius, the nearest island.Administratively, Réunion is one of the overseas departments of France...

, Rodrigues

Rodrigues

Rodrigues is a common surname in the Portuguese language. It was originally a Patronymic, meaning Son of Rodrigo or Son of Rui. The "es" signifies "son of". The name Rodrigo is the Portuguese form of Roderick, meaning "famous power" or "famous ruler", from the Germanic elements "hrod" and "ric" ,...

, and the Cargados Carajos Shoals

Cargados Carajos

Cargados Carajos Shoals are a group of about 16 small islands and islets on an extended reef in the Indian Ocean northeast of Mauritius. The islands have a total land area of 1.3 km². The reef measures more than 50 km from north to south, and is 5 km wide, cut by three passes. The...

.

Geology

The Indian subcontinent

Indian subcontinent

The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...

 was at one time next to the east coast of the Seychelles, but seafloor spreading

Seafloor spreading

Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. Seafloor spreading helps explain continental drift in the theory of plate tectonics....

 has moved the landmass to its current position, where it has collided and fused with the continent of Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

.

The northern part of the Mascarene plateau is formed of granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

, and is a fragment of the ancient supercontinent

Supercontinent

In geology, a supercontinent is a landmass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.-History:...

 of Gondwana

Gondwana

In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

. The granite is topped with deposits of limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 and basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

. The basalt deposits in the Seychelles are from the Deccan Traps

Deccan Traps

The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than thick and cover an area of and a volume of...

 eruption, which occurred in the central part of the Indian subcontinent 65 million years ago

Geologic time scale

The geologic time scale provides a system of chronologic measurement relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth...

, at the end of the Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period.

The southern part of the Mascarene plateau, also known as Southern Mascarene plateau (SMP), was formed by the Réunion volcanic hotspot

Réunion hotspot

The Réunion hotspot is a volcanic hotspot which currently lies under the Island of Réunion in the Indian Ocean. The Chagos-Laccadive Ridge and the southern part of the Mascarene Plateau are volcanic traces of the Réunion hotspot....

 along with the Chagos-Laccadive Ridge

Chagos-Laccadive Ridge

The Chagos-Laccadive Ridge , also known as Chagos-Laccadive Plateau, is a prominent volcanic ridge and oceanic plateau extending between the Northern and the Central Indian Ocean....

. The banks

Bank (geography)

A geographic bank has four definitions and applications:# Limnology: The shoreline of a pond, swamp, estuary, reservoir, or lake. The grade can vary from vertical to a shallow slope....

 and shoal

Shoal

Shoal, shoals or shoaling may mean:* Shoal, a sandbank or reef creating shallow water, especially where it forms a hazard to shipping* Shoal draught , of a boat with shallow draught which can pass over some shoals: see Draft...

s of the southern part of the Mascarene plateau were once volcanic islands

High island

In geology , a high island is an island of volcanic origin. The term can be used to distinguish such islands from low islands, whose origin is due to sedimentation or uplifting of coral reefs.-Definition and origin:...

, much like Mauritius and Réunion, which have now sunk or eroded to below sea level or, in the case of the Cargados Carajos, to low coral island

Coral island

A coral island is the result of an atoll whose lagoon has dried up or been filled in with coral sand and detritus. This state is typically the last in the life cycle of an island, the first being volcanic and the second being an atoll. Most of the world's coral islands are in the Pacific Ocean...

s. The Saya de Malha Bank formed 35 million years ago, and the Nazareth Bank and the Cargados Carajos shoals formed later. Limestone banks found on the plateau are the remnants of coral reef

Coral reef

Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...

s, indicating that the plateau was once a succession of islands

Archipelago

An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...

. Some of the banks may have been islands as recently as 18,0006,000 years ago, when sea levels were up to 130 meters lower during the most recent ice age

Quaternary glaciation

Quaternary glaciation, also known as the Pleistocene glaciation, the current ice age or simply the ice age, refers to the period of the last few million years in which permanent ice sheets were established in Antarctica and perhaps Greenland, and fluctuating ice sheets have occurred elsewhere...

. Mauritius formed 810 million years ago, and Rodrigues and Réunion formed around two million years ago. Piton de la Fournaise

Piton de la Fournaise

Piton de la Fournaise : "Peak of the Furnace" is a shield volcano on the eastern side of Réunion island in the Indian Ocean. It is currently one of the most active volcanoes in the world, along with Kīlauea in the Hawaiian Islands , Stromboli, Etna and Mount Erebus in Antarctica...

 volcano on Réunion is one of the most active volcano

Volcano

2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...

es in the world.