how does heat flow and movement of material within Earth move the continents,cause earthquakes and volcanic eruptions and create mountains
http://en.wikipedia.org/wiki/Plate_tectonics
Heat flow and material movement within the Earth are primarily responsible for the movement of continents, earthquakes, volcanic eruptions, and the creation of mountains. Let's discuss each of these processes separately:
1. Movement of Continents (Plate Tectonics):
The Earth's outer layer, known as the lithosphere, is divided into several large pieces called tectonic plates. These plates float on the semi-fluid layer underneath, known as the asthenosphere. The movement of these plates is driven by the flow of heat within the Earth. Here's an overview of the process:
- Heat generated by the decay of radioactive elements in the Earth's interior creates convection currents within the molten rock of the mantle.
- These currents cause the asthenosphere to flow and drag the overlying tectonic plates.
- The movement of the plates results in various interactions at their boundaries, such as subduction zones, divergent boundaries, and transform boundaries.
- Subduction zones occur when one tectonic plate slides beneath another, leading to the formation of volcanic arcs and trenches.
- Divergent boundaries happen when two plates move apart, allowing magma to rise and create new oceanic crust.
- Transform boundaries occur when two plates slide past each other horizontally, causing earthquakes due to the accumulated stress and release of energy.
2. Earthquakes:
Earthquakes are the result of the sudden release of energy that has built up along faults (cracks in the Earth's crust) over time. The movement and interaction of tectonic plates play a significant role in triggering earthquakes. Here's how it happens:
- As tectonic plates move, stress builds up along plate boundaries and faults.
- Eventually, this stress exceeds the strength of the rocks, causing them to fracture and release energy in the form of seismic waves.
- The sudden release of energy causes the ground to shake, resulting in an earthquake.
- Most earthquakes occur along plate boundaries, especially at subduction zones and transform boundaries.
3. Volcanic Eruptions:
Volcanic eruptions occur when molten rock (magma) from beneath the Earth's surface is ejected onto the surface. The movement of tectonic plates is closely linked to volcanic activity:
- Volcanoes often form at subduction zones, where one plate descends beneath another, creating intense heat and pressure.
- The descending plate introduces water and other volatile substances into the mantle, causing it to melt and generate magma.
- This magma, being less dense than the surrounding rocks, rises through cracks and fractures in the Earth's crust.
- Eventually, the magma may reach the surface, resulting in a volcanic eruption.
4. Mountain Formation:
The movement and collision of tectonic plates can also lead to the formation of mountains. Mountain-building processes are typically associated with convergent plate boundaries, where two plates collide. Here's how mountains are formed:
- When two plates converge, the leading edges crumple, fold, and buckle due to the immense pressure.
- This compression causes rocks to be pushed upwards and downwards, leading to the formation of mountain ranges.
- In some cases, the collision may also result in the formation of a subduction zone, where one plate slides beneath another, leading to the uplift of crustal rocks and the creation of mountainous terrains.
In summary, the movement of tectonic plates driven by heat flow and material movement within the Earth is responsible for the shifting of continents, triggering earthquakes and volcanic eruptions, as well as creating mountains.