Olympus Mons is thought to have formed over a long period of time, through the eruption of lava from a central vent. The volcano is no longer active, but it is still considered to be a young volcano by geological standards.
The question of whether Olympus Mons was once a giant volcanic island is a matter of debate. Some scientists believe that the volcano may have formed on the edge of a large crater, which was later filled in with lava. Others believe that the volcano formed on the open surface of Mars, and that it simply grew to its current size over time.
The evidence for the possibility that Olympus Mons was once an island comes from the presence of a number of large, flat-topped mesas around the base of the volcano. These mesas are thought to be the remains of volcanic islands that were once located in a sea that covered much of the surface of Mars.
The theory that Olympus Mons was once an island is supported by the fact that the volcano is located in the Tharsis volcanic province, which is thought to have been the site of a large amount of volcanic activity in the past. However, there is no definitive proof that Olympus Mons was ever an island, and the question is likely to remain a matter of debate for some time to come.
