Fold Mountains

Fold Mountains are usually formed from sedimentary rocks when two tectonic plates move together on a convergent boundary. The Himalayas and the Alps are two examples of fold mountains. Here is the Bitesize revision section on fold mountains, but also check out the excellent S-Cool revision site too. Have a look at the videos below too. I especially liked the song version done by a group of pupils to the tune of Bryan Adams' "Heaven".

Earthquakes

Earthquakes are a sudden release of energy from movement within the earth's crust. They are most common at plate boundaries. There are thousands of earthquakes across the globe every day but most are too small to be detected without special equipment, although big ones can cause massive destruction. Have a look at the resources mentioned here to help you understand the causes and effects of this natural disaster.
A good place to start is the BBC website which has a great selection of resources on earthquakes. Still with the BBC, Bitesize has a good revision section on earthquakes, as does S-Cool and Cool Geography. If you want to find out more about measuring earthquakes then have a look at the Geography Site.
Have a look at this video too to help you understand the phenomena.

Mount St Helens eruption

Mount St Helens in Washington State in the western United States erupted in May 1980 after two months of earthquakes and steam venting. The eruption caused the entire north face of the mountain to collapse, with the pyroclastic flow destroying everything in its path, melting glaciers on the mountain and then causing massive mud slides (lahars). The volcanic cloud spread across the USA in just three days and encircled the earth in two weeks.  This National Geographic video provides a great introduction to the topic, explaining how volcanoes are formed. Then take a look at this Discovery Channel video about the effects and this clip on the devastating effects of the Mount St Helens eruption.

 

Plate Tectonics

The idea that the earth's plates are in constant movement can be a confusing notion, but this extract from the series "Earth, the Power of the Planet" by Dr Iain Stewart gives an excellent explanation of the processes that are taking place.

Plate tectonics

For a very detailed and informative explanation of plate tectonics and the structure of the earth try these two links on the Moorlands School website.
For some beautiful satellite images of volcanoes have a look at the NASA site.