Social Science : Geography
LITHOSPHERE – II
VI. Distinguish between
• It is the break down of rocks without changing their chemical composition, through the action of physical forces
• Exfoliation, block disintegration granular disintegration etc are the different types of weathering
• Disintegration and decomposition of rocks due to chemical reactions is called chemical weathering
• Chemical weathering takes place through the processes of oxidation, carbonation, solution and hydration
• A triangular shaped low lying area formed by the river at its mouth.
• Deltas have fine deposits of sediments enriched with minerals eg. Cauvery Delta.
• Estuary is formed where the river meets the sea.
• Deposition of silt by the river is not possible here in the estuaries like delta as if the waves keep on eroding the deposits, eg. River Narmada and Tapti.
• When the water containing dissolved calcite gradually drips from the ceiling of the caves, water evaporates and the remaining calcite hangs from the ceiling. Thus stalactites are formed
• When the calcite deposits rises upward like a pillar Stalagmites are formed.
Longitudinal sand dunes
• Longitudinal dunes are long narrow ridges of sand, which extend in a direction parallel to the prevailing winds. These dunes are called Seifs in Sahara
Transverse sand dunes
• Transverse dunes are asymmetrical in shape. They are formed by alternate slow and fast winds that blow from the same direction
• Certain hard rocks like igneous rocks are more resistant to wind action.
• Such isolated residual hills rising abruptly from their surroundings are inselbergs. eg : Uluru, Ayers Rock, Australia
• In arid regions, certain rocks have hard and soft layers arranged vertically.
• When winds blow over these rocks the soft layers get eroded leaving irregular crests and are called Yardangs.
• A spit is a ridge or embankment of sediment, attached to the land on one end and terminating in open water on the other end. Spits are common at the mouth of estuaries.
• A bar is an elongated deposit of sand, shingle or mud found in the sea. It is almost parallel to the shoreline