Products of volcanic eruptions

Small streams have a stand density of honey, but in most cases, clutch their particles is much greater, at least, it takes some stress to stick a stick into the lava mass, and deepening that occurs at the same time, it remains for a full hour. Many streams can be compared with the semi-liquid cement. In some cases, as is the Humboldt and Bussengo in South America, they are not completely molten mass, and are a mixture of liquid magma from solid chunks. Speed ??of movement of the lava varies, depending on its density and the slope of the terrain where it makes its way. Relatively small lava flows that poured down the steep slopes, move forward very quickly; stream ejected Vesuvius on Aug. 12, 1805, raced up the steep slopes of the cone with amazing speed and in the first four minutes, U2 made 5 km> and in 1631 another thread the same volcano reached the sea in one hour, ie, was at this time of 8 km. Especially liquid lava stand open basalt volcanoes of the island of Hawaii, before they are mobile, that the cliffs form a real lavopady and can move at most a negligible slope of the soil, even in Mr. repeatedly observed, as these lavas were 10 - 20 and even 30 km per hour. But such a quick movement belongs in any case to the number of exemptions, even the lava, which saw Scrope in 1822 and which is within 15 minutes of time to get down from the edge of the crater of Vesuvius to the foot of the cone is not normal. At Etna lava movement believe is a quick, if it occurs at a speed of 1 km in 2 - 3 hours. Usually, the lava is moving and that slowly and in some cases is only 1 meter per hour. Lava flowing from a volcano in the molten state, has a white-glowing luster and inside the crater for a long time to save: it's good you can see where, due to cracks, exposed the deep part of the flow. Outside the crater lava cools rapidly and the flow will soon be covered solid crust, consisting of a dark mass of slag, for a short time it becomes so strong that people can safely walk on it, sometimes on a crust, covering all moving stream, can be reached before places where the lava follows. Solid slag crust is formed something like a tube inside which moves the liquid mass. Front end of a lava flow is also covered by a black hard crust, with further movement of the lava crust that presses to the ground and flows through it farther, covering the front of the new slag shell. This phenomenon does not occur only at a very fast moving lava, and in other cases by dropping and peredviganiya slag layer is formed of lava, by which the moving stream. The latter is a rare sight: the front part of his Pulet Scrope compares with a huge heap of coals, which, under the influence of some pressure from behind, pile up on each other. Its movement is accompanied by a noise, ringing like cast metal, this noise is due to the friction of individual lumps of lava, their fragmentation and reduction.