Magmatism is well known as one of the most important factors in the differentiation of matter of the earth. The recurrence of general paragenesis of magmatic rocks and their sequence in each new cycle of development of the lithosphere prove that they are identical processes and that they are present in the crust of our planet. Topics.- General principles for development of the basaltic series & methodology for their study; Basic features of geological structures of island arcs; Important types of volcanic series of island arcs & their distribution in time & space; Genesis of basaltic magma of island arcs; Petrology of andesites of island arcs; Basic features of deep-seated structures and geology of marginal seas & their types; Magmatism of continental blocks of the earth's crust & earlier subsided island arcs in marginal seas; Magmatism of deep-water basins of active seas; etc.