Pacific Ocean closed loop of the andesite line are most of the deep troughs, submerged volcanic mountains, and oceanic volcanic islands that characterize the Pacific basin. Here 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 named after the several hundred active volcanoes that sit above the various subduction zones. The Pacific Ocean is the only ocean which is almost
Circum-Baikal Railway in operation: Kultuk, Maritui, Ulanovo, and Baikal, with one section of double track at 137 km. The Circum-Baikal contains thirty-eight tunnels with a total length of 9063 m (the longest of them, a tunnel through cape Polovinnyj, is 777.5 m long). There are also 15 stone galleries with a total length of 295 m and 3 ferro-concrete galleries with apertures, 248 bridges and viaducts, and 268 retaining walls. The Circum-Baikal has no equal in Russia as to the richness of engineering constructions. The tunnels and stone galleries of the Circum-Baikal are unique in that they were constructed atypically and have