Exercise 2, page 38 Listen the attachment and complete the gaps with the correct missing words.

Have you 1) wondered how mountains are formed? If you know about volcanoes, you know a little bit already. The Earth's crust is made 2) of over 50 tectonic plates that push and pull to form mountains; and this happens so slowly that we don't even notice it. The wind, rain and ice also cause mountains to change shape. There are several types of mountains, so let's take a closer look at the three most common ones.

Fold Mountains

The most common type of mountain, formed over millions of years, is the fold mountain. Fold mountains form 3) two plates collide. The plates push against 4) other and the edges fold upwards. These folds can form whole mountain ranges, such as the Alps and the Himalayas.

Fault-Block Mountains

Sometmes there is pressure inside a plate that makes it crack instead 5) folding. Geologists call this crack a fault Iine. The pressure from inside the Earth pushes the crust of one or 6) sides of the fault ine up. This forms mountains, Iike the Sierra Nevada range in Califonia, USA.

Dome Mountains

Finally, dome mountains get their name because they look 7) a dome, or the top half of a ball. They are formed when hot melted rock (magma) 8) under the Earth's surface pushes up against the Earth's crust without breaking it. The Weald in the southeast of England was formed in this way.