The Andesite Line is the most significant regional distinction in the Pacific. It separates the deeper, basic igneous rock of the Central Pacific Basin from the partially submerged continental areas of acidic igneous rock on its margins. The Andesite Line follows the western edge of the islands off California and passes south of the Aleutian arc, along the eastern edge of the Kamchatka Peninsula, the Kuril Islands, Japan, the Mariana Islands, the Solomon Islands, and New Zealand. The dissimilarity continues northeastward along the western edge of the Albatross Cordillera along South America to Mexico, returning then to the islands off California. Indonesia, the Philippines, Japan, New Guinea, and New Zealand—all eastward extensions of the continental blocks of Australia and Asia—lie outside the Andesite Line. Looking down the Aleutians from an airplane. ... For other uses of Kamchatka, see Kamchatka (disambiguation). ... The Kuril Islands The Kuril Islands (Russian: Кури́льские острова́), also known as Kurile Islands, stretch northeast from Hokkaido, Japan, to Kamchatka, separating the Sea of Okhotsk from the North Pacific Ocean. ... Mariana Islands (sometimes called The Marianas; up to the early 20th century sometimes called the Ladrone Islands) are a group of islands made up by the summits of 15 volcanic mountains in the Pacific Ocean. ... The Solomon Islands is a nation in the South Pacific Ocean, east of Papua New Guinea and is part of the Commonwealth of Nations. ...

Within the closed loop of the Andesite Line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Central Pacific Basin. It is here that basaltic lavas gently flow out of rifts to build huge dome-shaped volcanic mountains whose eroded summits form island arcs, chains, and clusters. Outside the Andesite Line, volcanism is of the explosive type, and the Pacific Ring of Fire is the world's foremost belt of explosive volcanism. The Ring of Fire is a zone of frequent earthquakes and volcanic eruptions that encircles the basin of the Pacific Ocean. ...