Where old oceanic crust meets continental crust or younger oceanic crust at a convergent plate boundary it gets forced down into the mantle. This process does not necessarily happen when the crust is 180 millions years old. Rather, the oldest oceanic crust is found along the edges of the Atlantic ocean, dating to when it first formed in the Jurassic period.
A hydrothermal vent is formed when seawater seeps into cracks in the oceanic crust, gets heated by magma underneath, and then rises back to the seafloor. The high temperatures and pressure at these vents cause minerals and metals to dissolve in the hot water, creating unique underwater ecosystems.
The youngest rocks on the ocean floor are located at mid-ocean ridges, where new oceanic crust is formed through volcanic activity. As the crust spreads away from the ridge, it gets progressively older. This process is known as seafloor spreading.
When seawater freezes, the salt is expelled from the ice crystal structure, resulting in ice being formed with very low salt content. The expelled salt forms a concentrated brine solution, which can affect the surrounding seawater density and circulation patterns in the ocean.
The oceanic crust of the Atlantic Ocean floor is attached to the continental crust of the continents around the ocean. So as the Atlantic's Ocean floor spreads, the continents along its edges also move. Over time, the whole ocean gets wider.
The oldest rocks on the ocean floor would be those at the colliding edge of the plate boundary.Answer 2: The oldest of all oceanic rocks are on the Asian side of the pacific plate.
near ocean trenches.
In a sense, yes. The oceans lay on top of the crust. As the crust moves on top of the mantle at a speed roughly equivalent to the rate of fingernail growth, the ocean gets out of the way.
The age of rock increases with distance from mid-ocean ridges. At the ridges, new oceanic crust is formed through volcanic activity, which is young. As the crust moves away from the ridges, it cools and becomes older. This process is known as seafloor spreading.
When oceanic crust is still young, it's relatively warm. The older it gets, the colder it gets. The colder it gets, the less volume it takes in, however, it's still the same amount of matter. This causes a bigger density, thus causing the crust to sink deeper into the mantle.
When ocean water evaporates, the salt does not evaporate with the water. The water molecules evaporate, leaving the salt behind. This is why seawater is salty, as the salt remains in the ocean as the water evaporates.
Pieces of evidence for sea floor spreading include the presence of mid-ocean ridges where new crust is formed, symmetric magnetic striping on either side of mid-ocean ridges, age dating of oceanic crust that shows it gets older as it moves away from ridges, and the discovery of pillow basalts and other volcanic rocks on the ocean floor.