The nature and growth of magmatic plumbing systems are very important to geology. Traditionally, magma chambers have been viewed as bodies of molten rock or partially crystallized ‘magma mush’ connected to the surface by a narrow cylindrical conduit.
Recent data suggest, however, that magma chambers beneath volcanoes are formed gradually through the union of smaller conduits.
The knowledge of the internal three-dimensional structure of volcanic formations and how this influences the storage and transport of magma within plumbing systems is rather poor. This is because these systems cannot be observed directly and are usually studied through incomplete eroded outcrops. Such exposures commonly provide a limited view of the inner workings of volcanic systems, with most of the structure remaining buried and inaccessible, and key features, such as the conduit and chamber contacts, commonly missing.
An emerging view is that magma chambers are formed incrementally via amalgamation of numerous smaller intrusions into a single body, so that at any one time, only a small fraction of the chamber is molten.