Ricky Deloli, age 9, of Ottawa, Ont., for his question:

 What exactly is a volcano?

In 1943, the geologists had a chance to see the birth of a volcano. It happened near the mountain village of Paricutin, 200 miles west of Mexico City. The region is dotted with the cones of volcanoes. For this is an area where the earth's rocky crust is unsettled. Far below ground there are stresses and strains which cause earthquakes, volcanoes and the building of new mountains.

Certainly the ground seemed very unsettled in February 1943. For a week there were earthquakes every day. One day the earth rumbled and trembled 300 times. But the next day, February 20, farmer Dionisio Pulido was out tending his cornfield. Of all things, he saw a plume of smoke rising from a hole in the ground. This was too much. The story goes that farmer Pulido took matters into his own hands and carried stones to plug up the smoky hole.

This did no good at all. For the hole was a volcano. It was the mouth of a deep tunnel reaching perhaps 30 miles down into the earth. At its roots was a pool of hot molten rocks and gas called magma. The imprisoned magma was waiting to erupt to the surface.

When night came, the plume over the cornfield was higher and thicker. Dust, ashes and fiery rocks were being tossed into the air. By morning, this debris had fallen in a pile around the volcano, a pile ten foot tall. The pile grew day and night, forming the volcano’s cone. Dust and ashes fell for miles around. At night the young volcano lit up the sky. And day and night the seething crater hole was crowned with a billowing cloud of dusty smoke.

Then came the lava. Rivers of rod hot molten rock poured forth over the countryside. Farmlands, houses anal villages were buried. After three months the volcano's cone stood 1100 feet high. A year after farmer Pulido tried to bury the young volcano with a rock, the cone was 1, 400 feet high.

The volcano was named Paricutin for the first village it destroyed. It raged and grew for several years. Then it became calm. Paricutin may be dormant, asleep and waiting to erupt again. It may be extinct it’s fury ended forever. If so, in time the wind and weather will wear away the high hill it built over the farms and villages.

Each volcano has its own history. Some are active through many centuries. Some live only a few years. Sometimes a volcano seems to be extinct, only to burst forth with now fury. During their lives, volcanoes build some of the most beautiful of mountains. Shasta, Rainier, Hood and Whitney are mountains made by volcanoes.

All volcanoes have roots that go miles into the earth. Down there the temperature may be 2000 degrees Fahrenheit. Buried rocks may be heated to melting point. Where there are stresses and upheavals in the earths crust, pools of magma may collect. Far below every active volcano, a pool of magma waits to erupt through a vent, or tunnel, to the surface.