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SAI INTERNATIONAL SCHOOL
                      STD VII                                                SUBJECT - GEOGRAPHY
               TOPIC-CH – 3- Our Changing  Earth(LESSON NOTES)

               Sub-topic-       Major Land forms- Work of a River-cont. work of sea waves ,work
               of ice, work of wind
               Notes-
                   ÿ A floodplain is the area around a river that is covered in times of flood. It is a
                       very fertile area due to the rich alluvium deposited by floodwaters.A build-up of
                       alluvium on the banks of a river can create levees , which raise the river bank.
                   ÿ A distributary, or a distributary channel, is a stream that branches off and flows
                       away from a main stream channel. Distributaries are a common feature of river
                       deltas.
                   ÿ A river delta is a landform created by deposition of sediment that is carried by a
                       river as the flow leaves its mouth and enters slower-moving or stagnant water.
                       This occurs where a river enters an ocean,



               Work of sea waves-




                   ÿ SEA CLIFF- By the action of waves cracks occurred rocks, near shore Later
                       cracks becomes larger and pieces fall, away Steep slope form called sea cliff
                   ÿ SEA CAVES- Formed due to erosive action of waves, Sea side are carved out
                       form a hole, hole is called sea waves,
                   ÿ ARCHES - Erosive and weathered activity by sea, waves Sea caves are closed
                       to each other, joined together form arch shapes.
                   ÿ STACKS -The roof of the arches will collapse, by the continuous emotional
                       processes of  waves ,remaining structure called stacks.
                   ÿ The sea waves deposit sediments along the shores forming beaches.
               Work of ice-


                   ÿ When glacial ice melts, different types of rock are laid down that have been
                       carried along by the glacier. Piles of these deposits are called moraines.


               Work of wind-

                   ÿ Mushroom rocks are those rocks which are eroded from base due to the action
                       of wind. This process of undercutting produces rocks of mushroom shape.
                   ÿ Sand dunes are hills of sand that are made by winds as they blow across
                       deserts.
                   ÿ Loess can be defined as sediment that has been entrained, transported, and
                       deposited by the wind.
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