volcanoesA volcano is also called vulcan, which means place at the earth surface where volcanic material comes out, like lava and gasses. The conic shape of a volcano originates from the materials it brings up to the surface of the earth. At other planets like Mars and Venus there are also large volcanoes.
A volcano is formed bij a volcanic mass of lava and stone that comes out of the earth. It comes out through a canal. It is called eruption pipe. If an eruption pipe comes near the surface of the earth it forms a crater.
The big eruption cloud risis to greath heights. The tipical formed volcanoes may eventually erode. But the magmacenters and the eruptioncanals stay intact. They indicate early vulcanism. .
Kinds of volcanoes
There are different kinds of volcanoes. You can detect this by the gasses and the kind of lava and melted stone. These differences come from the composition of the magma, deep in the earth. basic lava is very liquid. The gasses escape easily.
Here you see where the volcanoes are
Sour lava is less liquid. The gasses escape not so easily thus leading to great pressures and explosions. Trough these explosions can big crators of several km diameter be forwed. If these holes become filled with water they are called explosionlakes. In other cases of explosions clouds of suspended lava particles in hot gasses are formed. These clouds come down and destroy everything they meet with their high temperature.
Recent volcanism is found in specific areas of the earth around the Pacific and in the middle of the Atlantic Ocean. Most working volcanoes are formed in the young chain mountains at the rims of the continents or on iland belts like the Antilles, Japan and Indonesia.
Apart from active volcanism there are also old volcanic rests. Old volcanism you find as sulphur springs and carbonic-acid springs and hot geysers. In older mountains you can find old lava streams, passages and old craters
Volcanism is caused by magma chambers. These maga chambers lie 10 - 20 km beneath the earthsurface. The high presure can push the volcanic material through cracks and clefts to the higher parts of the earthcrust. Most of the contents of the magma chambers never reaches the surface. This subvolcanism has a role in the forming of ores. For instance tin in Bolvia gold and silver in eastern europe and zinc in Germany and France.