Aromatic and Glutinous rice varieties are seen in both Indica and Japonica main types of rice. There are more than 40,000 varieties of cultivated rice (grass species Oryza sativa) said to exist. But the exact figure is uncertain. Over 90,000 samples of cultivated rice and wild species are stored at the International Rice Genebank and these are used by researchers from the world.
Plate Tectonics-Formidable Forces. Plate tectonics is the fundamental mechanism that drives geological processes in the geosphere. Plate tectonic theory is based on an understanding of the Earth's internal structure, the different types of tectonic plates and plate boundaries, and the driving forces of plate movements.Figure 4a): occur where two lithospheric plates move away from each other, driven by magma rising from deep within the mantle. Volcanic activity at a divergent plate boundary creates new lithosphere along what is known as a spreading ridge. Figure 4b: Generalised structure of a convergent plate boundary.
Plate tectonics is a theory of geology. It has been developed to explain large scale motions of the Earth 's lithosphere. This theory builds on older ideas of continental drift and seafloor spreading. Dissipation of heat from the mantle is the original source of energy driving plate tectonics. Exactly how this works is still a matter of debate. The driving forces of plate motion continue to be active subjects of on-going research.