The suboceanic mantle.

An independent determination of density in the suboceanic lithosphere gives 3.5 to 3.6 grams per cubic centimeter at a depth of about 100 kilometers. This high value implies the existence of an ecologitic facies. A mechanism is proposed in which eclogite fractionation from the underlying, partially molten asthenosphere plays a key role in the creation and the spreading of the rigid, lithospheric plate.