1. The lava that is released during volcanic eruptions on cooling develops into igneous rocks.

2. The cooling may take place either on reaching the surface or from the inside itself.

3. Depending on the location of the cooling of lava, igneous rocks are classified as:

1. These volcanoes occur in the oceanic areas.

2. There is a system of mid-ocean ridges more than 70,000 km long that stretches through all the ocean basins.

3. The central portion of this ridge experiences frequent eruptions.

1. These volcanoes outpour highly fluid lava that flows for long distances.

2. The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province.

1. These are the most explosive of the earth’s volcanoes.

2. They are usually so explosive that when they erupt they tend to collapse on themselves rather than building any tall structure. The collapsed depressions are called calderas.

3. Their explosiveness indicates that its magma chamber 

1. Shape: Cone shaped with moderately steep sides and sometimes have small craters in their summits.

2. Volcanologists call these “strato-” or composite volcanoes because they consist of layers of solid lava flows mixed with layers of sand- or gravel-like volcanic rock called cinders or volca

1. Cinders are extrusive igneous rocks. A more modern name for cinder is Scoria.
2. Small volcanoes.
3. These volcanoes consist almost entirely of loose, grainy cinders and almost no lava.
4. They have very steep sides and usually have a small crater on top.

1. How to identify: They are not very steep but are far and wider. They extend to great height as well as distance.
2. They are the largest of all volcanoes in the world as the lava flows to a far distance. The Hawaiian volcanoes are the most famous examples.
3. Shield volcanoes have low slopes an