Tuesday 8 th February 2011 Waterfalls What is

Tuesday 8 th February 2011 Waterfalls

What is a waterfall? • Definition?

What is a waterfall? • Definition A waterfall is a geological formation where flowing water rapidly drops in elevation as it flows over a steep region or a cliff.

How are waterfalls formed? Copy out the paragraph below and insert the missing words from the word bank. Waterfalls occur when ______ flow over different types of ____. The ____ rock wears away faster than the ____ rock. In time a step develops over which the river _______ as a waterfall. _____also cuts away rock behind the _____. This causes the falls to move back and leave a _____ as it goes. HARD SOFT RIVERS WATERFALL PLUNGES ROCK GORGE

How are waterfalls formed? Copy out the paragraph below and insert the missing words from the word bank. Waterfalls occur when RIVERS flow over different types of ROCK. The SOFT rock wears away faster than the HARD rock. In time a step develops over which the river PLUNGES as a waterfall. WATER also cuts away rock behind the WATERFALL. This causes the falls to move back and leave a GORGE as it goes.

How are waterfalls formed? The diagrams below have been given the wrong labels. Can you figure out which description matches each diagram? 1. The hard rock collapses into the plunge pool to be broken up and washed away by the river. The position of the falls moves back. 2. Falling water and rock particles or boulders loosen and wear away the softer rock. 3. Erosion continues and the waterfall slowly eats its way upstream leaving a gorge behind. 4. The hard rock above is undercut as erosion of the soft rock continues.

How are waterfalls formed? The diagrams below have been given the wrong labels. Can you figure out which description matches each diagram? 2. Falling water and rock particles or boulders loosen and wear away the softer rock. 4. The hard rock above is undercut as erosion of the soft rock continues. 1. The hard rock collapses into the plunge pool to be broken up and washed away by the river. The position of the falls moves back. 3. Erosion continues and the waterfall slowly eats its way upstream leaving a gorge behind.

How are waterfalls formed? In your exercise books, draw each of the four diagrams and write the descriptions for each one. Falling water and rock particles or boulders loosen and wear away the softer rock. The hard rock above is undercut as erosion of the soft rock continues. The hard rock collapses into the plunge pool to be broken up and washed away by the river. The position of the falls moves back. Erosion continues and the waterfall slowly eats its way upstream leaving a gorge behind.

How is a waterfall worn away? In your exercise books, draw a cycle to show a waterfall is worn away. Put the labels below on the cycle in the right order. • • • Hard rock collapses Soft rock worn away Waterfall moves back Plunge pool deepens Hard rock undercut ? ? ?

How is a waterfall worn away? Soft rock is worn away Waterfall moves back Hard rock collapses Hard rock is undercut Plunge pool deepens

Waterfall diagram • Look at the diagram on the handout. Use the word bank to label the diagram.

Waterfall diagram • Look at the diagram on the handout. Use the word bank to label the diagram. A = WATERFALL B = PLUNGEPOOL C = RIVER D = SOFT ROCK UNDERCUT E = HARD ROCK OVERHANGS F = GORGE

Waterfalls of the World; Fact File • • Angel Falls, Venezuela (979 m high, 47 drops) Niagra Falls, Canada & USA (52 m high, 1 drop) Iguazu Falls, Argentina (82 m high, 275 drops) Victoria Falls, Zimbabwe (108 m, 1 drop)

Plenary; Mystery Picture