The magma in a magma chamber usually exists in several layers, based upon the density of the materials composing the lava. The least-dense magma rises to the top, while the denser magma settles toward the bottom of the magma chamber.
Full Definition of ACCRETION. 1. : the process of growth or enlargement by a gradual buildup: as a: increase by external addition or accumulation (as by adhesion of external parts or particles) b: the increase of land by the action of natural forces. 2. â acÂ·creÂ·tionÂ·ary \-shÉ-Ëner-Ä, -Ëne-rÄ\ adjective.
615 pages on this wiki. In astrophysics, the term accretion is used for at least two distinct processes. The first and most common is the growth of a massive object by gravitationally attracting more matter, typically gaseous matter in an accretion disc.Accretion discs are common around smaller stars or stellar remnants in a close binary or black holes in the centers of spiral galaxies.n the nebular theory, accretion refers to the collision and sticking of cooled microscopic dust and ice particles electrostatically, in protoplanetary discs and gas giant protoplanet systems, eventually leading to planetesimals which gravitationally accrete more small particles and other planetesimals.