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Answer:
A river basin or drainage basin is an area of land drained by a river and its tributaries. The edge of the drainage basin is known as the watershed. This can be compared to a sink or basin, which catches the water falling into it. The water travels towards the centre and leaves the sink through a plug hole.
A shield<span> is generally a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that </span>form<span> tectonically stable areas. In all cases, the age of these rocks is greater than 570 million years and sometimes dates back 2 to 3.5 billion years.</span>