Karst topography is a result of the dissolution of soluble rocks like limestone, dolomite and gypsum. Caves are formed due to weathering of rock deep underground. Cave or cavern is a natural void and is a space large enough so that a human can enter. The study of the formation and development of caves is called as Speleogenesis. Most of the formation of caves takes place in limestone rocks by dissolution.
The Thermosphere is located between 80 and 400 km above the mesopause. It contains electrically charged particles known as ions. It is therefore known as Ionosphere. The temperature here starts increasing with heights. Radio waves transmitted from the earth are reflected back to the earth by this layer. The International Space Station and other satellites orbit in this layer. Auroras are observed in the lower parts of this layer.
EXAMIANS