The
Lithosphere- Asthenosphere boundary represents a
mechanical difference between layers in Earth’s inner structure. Earth’s inner structure can be described both
chemically (
crust,
mantle,
core) and mechanically. The Lithosphere-Asthenosphere boundary (referred to as the LAB by geophysicists) lies between Earth's cooler, rigid
lithosphere and the warmer, ductile
asthenosphere. The actual depth of the boundary is still a topic of debate and study, although it is known to vary according to the environment.