2. Write the short note on (a) work of river and
(b) work of wind.
Answers
A short not on river:
The running water in the river erodes the landscape.
When the river tumbles at a steep angle over very hard rocks or down a deep valley side it forms a waterfall.
While entering the plain the river twists and turns and forms large bends which are known as meanders. Due to continuous erosion and deposition along the sides of the meander, the ends of the meanders loop come closer and closer. In-due course of time the meander loop cuts off from the river and forms cut-off lake, which is also called an ox-blow lake.
Sometimes, the river overflows its banks causing flood in the neighboring areas. As it floods, it deposits layers of the fine soil and other material called sediments along its banks. As a result fertile floodplain is formed. The raised banks are called levees.
As the river approaches the sea, the speed of the flowing water decreases and the river begins to break up into several streams known as distributaries. Then a time comes when the river becomes very slow and it begins to deposit its load. Each distributary forms its own mouth. The collection of sediments from all the mouths forms a delta, which is a triangular landmass.
A short note on wind:
Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk movement of air. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn. Winds have various aspects: velocity (wind speed); the density of the gas involved; energy content or wind energy. The wind is also a critical means of transportation for seeds, insects, and birds, which can travel on wind currents for thousands of miles.