Ok, right, time goes by and it was my second time to write the post.
In the 30 minutes lesson, we have learnt about the WATERFALL and MEANDER.
So let’s begin with the waterfall. The waterfall is a steep descent of water from a height. It usually found in the upper course of a river in the hills or mountains.
A WATERFALL=A STEEP DROP OF WATER
Formation of Waterfalls:
--It forms when a band of hard resistant rock lies over softer, less resistant rock.
--The softer rock is quickly eroded by hydraulic action and abrasion, causing the harder rock to be undercut.
--The hard rock overhangs until it can no longer carry its own weight.
--The overhang collapses and then breaks up in the water below.
--The great power of the water at the base of the waterfall causes a plunge pool to form.
--The bed of the river below the waterfall contains boulders eroded by splash back from behind the waterfall.
Some Facts of Waterfalls:
The tallest waterfall in the world is the Angel Falls. It is 979 metres high.
The highest waterfall in Africa is the Tugela Falls at 947 metres. It is found in South Africa.
Europe's highest waterfall, Utigard in Norway, is 800 metres high.
The Yosemite waterfall (739 metres) is the highest waterfall in the USA.
Secondly, we learnt meanders which are curves or bends along a river. It is usually found in the middle or lower course of a river.
MEANDER=A BEND IN A RIVER
Formation of Meanders:
A meander is formed when the moving water in a river erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternatively eroding sediments from the outside of a bend and depositing them on the inside. The result is a snaking pattern as the stream meanders back and forth across its down-valley axis.
Cause of Meanders:
Helicoidal Flow=Spiral Movement of Water
It will move eroded river load from the outer bank and then deposited much of it on the next inner bank of a river.
Top current: hits against the river bank and undercuts the eroded material.
Bottom current: carries the eroded material and deposits them in the next inner bank.
Yeah, I guess it’s all. Hope you can understand.
Enjoy the half day, heh heh.
Done by Violet
hellos! yayyz, i finally somewhat understand the formation of waterfalls and meanders after reading the post! haha, yayyz, and the fact that there's like so many pictures and little words makes reading and trying to understand so much nicer(: thanks dengxuan! anw, the explanations are also quite detailed like when it is specified that it's the top current which erodes and the bottom current which carries the eroded material(: haha, okays, i shall continue studying for geog test tmr, jiayous everyone:DD