Phacoliths Small 320×145 Medium 640×289 Large 1024×463 Download TIFF Original 2400×1085 | (206.6 KB) Description Diagram illustrating the formation of phacoliths (shown in solid black). A phacolith is an intrusion of liquid rock formed when magma pushes up from deep within the earth into any cracks or spaces it can find. Keywords diagram, formation, intrusion, magma, phacolith, pluton Galleries Structural Geology Source: Amadeus W. Grabau A Textbook of Geology (Boston: D.C. Heath & Co., 1920) 202
