The time required for cooling lava

Some of the threads over the years form the fumaroles. At Horullo in Mexico, in the keys held by the lava, which poured 46 years ago, Humboldt observed the temperature of 54 °. Flows of considerable power freeze even longer. Skapmar-iokul in Iceland in 1783 to focus on two lava flows, the volume of which surpassed the volume Motsblana, it is not surprising that such a powerful mass of solidified gradually over 110 years. We saw that the lava flows quickly solidifies on the surface and put on a solid crust, where the liquid mass is moving, as if in a tube. If after this amount of emitted lava reduced, then such a pipe is not completely filled it: the top cover will be gradually lowered, stronger in the middle and lower edges, instead of a convex surface, which is any thick fluid mass, you get a concave surface in the form of a chute. However, the solid crust, dressing flow drops do not always: if it is sufficiently powerful and strong, it will withstand its own weight, in such cases within the frozen flow voids are formed, without a doubt, this is by having the famous caves of Iceland. The most famous among them enjoys Surtshellir ("Black Cave") in Kalmanstunga, located in a vast lava field, its length of 1600 m, width 16 - 18 m and height, and - 12 m. It consists of a main hall with a number of side chambers. The walls of the grotto are covered with shiny vitreous formations from the ceiling down the magnificent lava stalactites, the sides are visible long strips - should go flaming mass. Many of the lava flows of Hawaii Island erupt long caves, tunnels, such as: places of these caves are very narrow, sometimes extended to 20 m tall and form large rooms, decorated with stalactites, they sometimes stretch for many kilometers and twists, following all the directions of the lava flow. Such tunnels have been described as the volcanic islands of Bourbon (Reunion) and Amsterdam.