Asthenosphere -

Earths mantle layer located at depths ra nging from 100 to 400 km beneath the Earths surface. Rock materia l in the layer astenosfery is partially melted, has a viscosity g reater than the viscosity of the lithosphere and is flexible. Acc ording to a recent geophysical study the continents are embedded to a depth of about 400 km, which excludes the existence of a continuous film astenosfery. According to the theory of plate tectonics convection movements astenosfery cause movement of tectonic plates and wandering continents.