Lithosphere-Asthenosphere boundary a thermal control of oceanic-lithosphere thickness. The continental lithosphere contains an ancient, stable part known as the craton. The LAB is particularly difficult to study in these regions and evidence suggests that the lithosphere within this old part of the continent is at it thickest and even appears to exhibit large variations in thickness beneath the cratons, thus supporting the theory that lithosphere thickness and LAB depth are age-dependent. Depths of the LAB beneath these regions (also known as shields and platforms) are estimated to be between 200 and 250 km deep. Beneath Phanerozoic continental crust, the LAB is roughly
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