Give reasons for the following:

Volcanos have constructive effects in favour of man.

Volcanos have constructive effects in favour of man because:

1. Lava from plains are very fertile. For example- plains in Java, Malwa region in Deccan plateau and parts of Brazil.
2. Lava activity also provides us precious stones.
3. Geyser and springs are formed that provide water with health benefits.
4. Crater lakes are formed which serve as source of water to perennial rivers. For example-Lake Nyos.
5. Sometimes remnants of volcanoes after erosion helps in preserving traces of old civilization.