Lithosphere-Asthenosphere boundary Lithosphere-Asthenosphere boundary The Lithosphere-Asthenosphere boundary (LAB) 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. The LAB is determined from the differences in the lithosphere and asthenosphere including, but not limited to, differences in grain size, chemical composition, thermal properties, and
Earth science in the same ways throughout geologic time. This enables those who study Earth's history to apply knowledge of how Earth processes operate in the present to gain insight into how the planet has evolved and changed throughout deep history. Earth science generally recognizes four spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere; these correspond to rocks, water, air and life. Also included by some are the cryosphere (corresponding to ice) as a distinct portion of the hydrosphere and the pedosphere (corresponding to soil) as an active and intermixed sphere. Earth science Earth science or geoscience includes all fields