what could be the cause of continental drift?
http://sci.waikato.ac.nz/evolution/PlateTectonics.shtml
http://geophysics.suite101.com/article.cfm/understand_plate_tectonics_continental_drift
The cause of continental drift is primarily attributed to the theory of plate tectonics. Plate tectonics explains how Earth's outermost layer, known as the lithosphere, is divided into several large plates that float on the semi-fluid asthenosphere beneath them. The movement of these plates over time leads to continental drift. Here are the step-by-step factors contributing to this phenomenon:
1. Convection currents: Heat generated from radioactive decay in Earth's core creates convection currents in the asthenosphere. These currents act like a conveyor belt, moving the lithospheric plates located above them.
2. Lithospheric plates: The lithosphere is divided into approximately 12 major plates, along with several smaller ones. These plates are made up of both oceanic and continental crusts.
3. Plate boundaries: The plates interact with one another at their boundaries. There are three types of plate boundaries:
a. Divergent boundaries: Plates move apart from each other, creating tension and leading to the formation of new crust. This occurs primarily along mid-ocean ridges, where magma rises to fill the gap between the separating plates.
b. Convergent boundaries: Plates collide with each other, resulting in the destruction or creation of crust. There are three subtypes of convergent boundaries:
- Oceanic-oceanic convergence: One oceanic plate dives beneath another, forming a deep-sea trench and volcanic activity. This process is known as subduction.
- Oceanic-continental convergence: Oceanic plates subduct beneath continental plates, leading to the formation of mountain ranges (such as the Andes) and volcanic activity.
- Continental-continental convergence: When two continental plates collide, neither can subduct due to their low density. Instead, the plates crumple and uplift, causing the formation of large mountain ranges (such as the Himalayas).
c. Transform boundaries: Plates slide past each other horizontally. This leads to intense pressure and friction, causing earthquakes along fault lines (e.g., the San Andreas Fault in California).
4. Plate motion: The continuous movement of these plates, driven by the convection currents, can result in horizontal movement, pushing, or lateral displacement of continents over millions of years. This process is known as continental drift.
It is important to note that the theory of plate tectonics and continental drift are widely accepted in the scientific community, with ample evidence supporting these concepts.
The cause of continental drift can be explained by plate tectonics. Plate tectonics is the theory that explains how the Earth's outer layer, known as the lithosphere, is divided into several large and small plates that are constantly moving.
The primary driving force behind continental drift is the movement of these tectonic plates. There are three main types of plate boundaries: divergent, convergent, and transform.
Divergent boundaries occur when plates move away from each other. This movement creates tension and results in the formation of new crust through volcanic activity. As new crust is formed, it pushes the continents apart, causing them to drift.
Convergent boundaries happen when plates collide with each other. In this case, one plate may be forced beneath the other in a process called subduction. The subduction of oceanic crust beneath continental crust can cause continents to be pulled together, leading to the shrinking or merging of landmasses.
Transform boundaries occur when plates slide past each other horizontally. The friction between the plates can cause immense pressure to build up. When the pressure is finally released, it results in earthquakes and the lateral movement of the plates. This movement can also cause continents to shift.
In summary, the cause of continental drift is mainly attributed to the movement of tectonic plates at plate boundaries. This movement can result in the separation, collision, or sliding of continents over long periods of time.