From its origins, our planet is composed of various layers that formed while heavy materials fell towards the center and lighter ones surfaced. Some of the layers produce chemical or structural changes that cause discontinuities. Less heavy elements, such as silicon, aluminum, calcium, potassium, sodium and oxygen, make up the outer crust.
The plates that form the earth's crust are floating on pasty materials under heavy pressure. They move slowly with respect to each other. In the past they were united, then they separated forming the current continents.
Due to these movements and the pressure on the internal materials, various phenomena occur: land folds, faults, cracks, volcanoes and earthquakes. We live on a surface that, far from being stable, changes over time.
In this chapter…
In this chapter:The plates of the earth's crust: The terrestrial surface, the lithosphere, is divided into plates that move at the rate of about 2 ... Read pageThe continental drift: This is the name of the phenomenon by which the plates that support the continents move at along ... Read pageThe continuous movement: What has happened, at least once, can happen again. And it will happen. The movement of the plates ... Read pageTectonics of plates: For billions of years there has been a slow but continuous movement of the plates that ... Read page Oceanic expansion: In the ocean floor the plates move away and there is a gap between them it is filled with material from ... Read page Formation of mountains: the folds: The earth's crust is solid, but as new portions are constantly generated and ... Read pageFailures of the earth's crust: Failures are a type of deformation of the earth's crust that ends in rupture, giving rise ... Read pageThe volcanoes: One of the most spectacular manifestations of the geological activity of the Earth are, without a doubt, the volcanoes ... Read pageTypes of volcanoes: Volcanoes have been classified into several large groups or types, although the we must not fit exactly in ... Read page Earthquakes: Earthquakes, earthquakes, earthquakes, earthquakes ... they are readjustments of the earth's crust caused by the… Read page Seashells and Tsunamis: A tsunami is a sudden invasion of the coastal strip by ocean waters due to a tsunami, a large… Read page