Treatise on Physical Geology, Deep Earth Dynamics and Seismology

• Asthenosphere — A layer ofthe solid Earth located in the upper mantle, directly below the lithosphere (at a depth between approximately 100 and 410 kilometers); it is characterized by rocks in a plastic, viscous, and partially molten state due to high temperatures and pressures, allowing the slow movement of overriding tectonic plates through convection currents.
• Astian — Pertaining to or relating to the Astian, a historical chronostratigraphic subdivision of the Upper Pliocene in Europe (primarily used in the Mediterranean basin to describe marine sedimentary deposits rich in fossilized malacofauna); the term is derived from the name of the city of Asti in Italy.