UNIT 10: THE EARTH'S RELIEF

UNIT 10: THE EARTH´S RELIEF

1.-Internal Processes

In this unit we will learn more about the Earth´s relief and how internal processes change it.

High temperatures inside the Earth cause very slow movements that have enough force to move entire continents. These cause internal processes that later come to the Earth´s surface, like when volcanoes erupt or when there are earthquakes.

1.1.-Volcanoes

A volcano is an opening on the Earth´s surface that lets lava, ash, and gases escape from below, from inside the Earth.

The lava is a mixture of molten rock, gases and pieces of rock. When the lava comes out with great force and energy, it is called an eruption.

A volcano has three main parts:* A main vent. This is the main vertical channel the magma rises through to the surface.* A crater. This is the hole the lava comes out of at the top of the volcano.* A volcanic cone. These are the mountains that are made up of the rock and hard lava that accumulate near the crater when the
magma comes up to the surface.

1.2.- Earthquakes

Earthquakes are when the ground at a certain level of the Earth´s crust shakes.

Every earthquakes starts at a specific point in the inside of the Earth.

This point is called the hypocentre. Movement is transmitted vertically from this point towards the Earth´s surface. The point where an earthquakes first reaches the Earth´s surface is called the epicentre.

Seismic waves spread the movement along the surface. If this movement is very strong, it can change the Earth´s relief.

Activities

1.- Name the three main parts of a volcano and explain them

2.- What is an Earthquake?

3.- True or false and underline. Check when it is neccessary.

• a) A volcano expels lava and gasses

• b) The crater is the hole at tyhe top of the volcano.

• c) A mantle is the hole comes out of a top of the volcano.

• d) Magma is the mixture of rock, gases and pieces of rock that reaches the Earth's surface.

• e) The point where an earthquake first reaches the Earth's surface is called the hypocentre.