In English common law, fee tail or entail is a form of trust established by deed or settlement which restricts the sale or inheritance of an estate in real property and prevents the property from being sold, devised by will, or otherwise alienated by the tenant-in-possession, and instead causes it to pass automatically by operation of law to an heir ...
Oceanic-Continental Plate Convergence. When an oceanic plate collides with a continental plate the crust forming the oceanic plate gets bent and pulled under the continental crust. This is because the rocks that form the oceanic crust are denser and thinner than the rocks that form the continental crust. The process by which the oceanic crust is pulled under the continental crust is called subduction and the zone at which this occurs at the plate boundaries is called the subduction zone. At the subduction zone where the oceanic crust sinks beneath the continental crust a deep oceanic trench or valley is created.
Subduction boundaries occur where oceanic lithosphere is pushed beneath continental or oceanic lithospheres. Where two plates converge at an oceanic trench a subduction boundary is formed as cold oceanic lithospheres are pushed back down into the mantle. This happens because the oceanic plate is denser than the continental plate so, as they move together, the oceanic plate is forced underneath the continental plate. In this case, one plate overrides, or subducts the other, pushing it slowly downward into the mantle where it melts to form magma.