Revision on Geography

The ___________ is the densest layer of the Earth. This is because the pressure of the surrounding Earth results in compression which causes the density to increase.

• crust

• mantle

• core

• plate

Which of the following is not the consequence of volcanic eruptions?

• Increase in visibility

• Fire

• Mudflows bury large piece of land

• Emission of lava and poisonous gases

Seventy-five percent of the world's active volcanoes are positioned around the _______, a horseshow-shaped zone that stretches from South America across the west coast of _______, through the Bering Sea to Japan, and then to Australia in the Southern Hemisphere.

Most volcanoes form along the boundaries of Earth's tectonic plates, except the _______ plate boundary. When the plates collide, one often plunges deep below the other in what is known as a _______. As the descending landmass sinks deep into the Earth, temperature and pressures increase. Finally, _______ is formed underground. After eruption and solidification, volcanoes are formed.

Volcanic eruptions pose many dangers like _______, which are movements of hot molten rock that comes out of a volcano. _______ is another volcanic danger. Unlike the soft, fluffy bits of charred woof left after a campfire, it is made of tiny sharp fragments of rocks which are dangerous to inhale.