Thursday, November 15, 2012

Some like it hot... volcanoes that is!

Have you ever seen a volcano? When looking at one, you feel amazingly insignificant! You think of the awesome power that they hold within them, and it causes a fearful respect!

How do volcanoes start?
Scientist think that volcanoes begin as an underground bubble of lava. This magma or melted rock is lighter than solid rock it wants to rise toward the earth's surface. If there is a crack or weak spot in the crust, it will find its way through and form a large chamber or reservoir called a magma chamber just below the earth's surface.

The magma begins to melt nearby rock and this increases the pressure in the chamber. This begins to push against the surrounding rock and causes it to split apart. The magma is then forced through this split and out the vent or opening. As it begins to spew, the cooling magma begins to form a rock. Yet the molten rock or magma still continues to spew forth. It keeps cooling and spewing until a new mountain is formed!

Volcanoes tend to occur in specific areas that lie between the boundaries of the plates. There is a lot of volcano activity in one area which is called the ring of fire. This is the edge of the Pacific plate.

Thursday, November 1, 2012

Moving Crust?

Like we mentioned before our earth is an amazing place! There are so many mysteries hidden beneath our feet. One of those mysteries is that of the drifting or moving crust. You see the earth's crust is actually made up of plates that float like rafts on the water. These plates are often moved when heat rising from below the crust pushes them from place to place.

Sometimes these plates will collide or grind together. When they collide they may often buckle producing mountains. In fact, most of our earth's ranges are found near plate edges. These plates are responsible for the trenches and mountains that are found in the oceans. When plates move apart, they create a gap. The gap will sometimes fill with molten lava, but it will still leave a deep crack. These cracks are the immensely deep ocean trenches.

What do you think happens when the plates grind against each other? They produce earthquakes. The rough edges grind against each other and then sometimes stop. Yet, the pressure to move is still there. When the rocks finally give in they crack, the plates jump ahead and move. This is what causes an earthquake to happen. Sometimes the rocks will just bend without moving - and that is called a fold. Other times, the rocks will just crack without moving and that is called a fracture.

Earthquakes can be measured by their magnitude on a Richter scale. About 80% of earthquakes occur within a the circum-pacific belt. This is the edge of the plate that circles the Pacific Ocean.