<span>Covered by the two cerebral hemispheres, the diencephalon is
the structure of the central nervous system that surrounds the third ventricle.
It is composed of several other structures. The most important of them are the
Thalamus, which plays a very important role in movements and emotions; and the
Hypothalamus, which provides functions including thermoregulation, appetite and
regulation of the sleep-wake cycle.</span>
Sedimentary rocks are formed overtime are different particles of sand, shells, pebbles and other fragments of materials form layers and harden into rock.
