"The Formation of Pebbles" Changes in Ground Form PPT Courseware

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"The Formation of Pebbles" Changes in Ground Form PPT Courseware

What is the name of the stone in the picture? What are the characteristics?

smooth round

What are the characteristics of stone distribution in rivers?

The stones are large, angular and rough.

The stones are larger, have sharp edges and corners, and have a rough surface.

The stones are small, have unclear edges and corners, and have a smooth surface.

Based on the distribution of stones in the river, where do the pebbles come from?

My theory: The pebbles came from upriver.

Why do rocks on high mountains continue to crack, break, and collapse?

Use pliers to hold a stone and heat it over an alcohol lamp, then immediately place the hot stone into cold water. Repeat it several times and see what changes happen to the stone?

When cracks occur in the rock, rainwater will flow into the cracks. What will happen when the temperature drops to 0°C? What effect does it have on rocks?

Water will freeze and split the rock. This effect of destroying the rock is called ice splitting.

Ice splitting breaks rocks

When rocks develop cracks, rain washes soil into the cracks. What happens when wild plant seeds fall into the cracks? What effect does it have on rocks?

Wild plant seeds will germinate, and the roots of the plants will grow and crack the rocks.

Tree roots swell and crack, shattering rocks

In the process of water transport, how do the rocks in the upper reaches of the river turn into pebbles on the river beach in the lower reaches?

My guess: It may have been turned into pebbles by the impact of water flow, collision of rocks, and friction.

Simulation experiment: Put a few small bricks into a glass bottle, fill it with water, close the bottle cap tightly, shake vigorously, and observe what changes happen to the small bricks?

Experimental steps

1. Observation before the experiment: What are the characteristics of bricks?

The bricks are larger, with sharp edges and rough surfaces.

2. Simulation experiment: shake the glass bottle vigorously

3. Observation after the experiment: What changes happened to the bricks?

Bricks are smaller, have less sharp edges and corners, and have a smooth surface.

4. Analyze the results: How do bricks become smooth?

The bricks are impacted, collided, and rubbed by the water flow, and gradually become smooth.

I know

1. Pebbles: We call the smooth and round stones on the river beach pebbles. The rocks in the upper reaches of the river turned into pebbles on the river beach in the lower reaches during the transportation of water.

2. Weathering: Rocks on high mountains are constantly broken and collapsed by temperature changes, ice splitting, and tree roots swelling. This kind of destruction of rocks is called weathering.

3. Formation of pebbles: The rocks on the mountains are weathered and transported to the river by water flow. During the process of being impacted, collided and rubbed by the water flow in the river, they gradually turn into smooth pebbles.

I will do it

1. Fill in the blanks:

1. We call the smooth and round stones on the river beach _____.

2. Rocks on high mountains are constantly broken and collapsed by _____, _____, _____. This kind of destruction of rocks is called _____.

3. The rocks in the river gradually become _____ on the river beach under the influence of the flowing water.

4. The rocks on the mountain pass through _____ and _____ into the river. When they are _____, _____, _____ by the water in the river, they gradually turn into pebbles with smooth surfaces.

2. Judgment:

1. There are often many smooth and round pebbles in the upper reaches of the river, while there are sharp-edged stones in the lower reaches. ( )

2. The stones under the mountains in the upper reaches of the river fell from the mountains due to loosening of the mountains, cracks in the mountains or swelling and cracking of tree roots. ( )

3. Stone is very hard and its shape never changes. ( )

4. The sandbanks in the river and the gullies on the plateau are all formed by the action of flowing water. ( )

3. Short answer

1. How are pebbles formed?

Answer: The rocks on the mountains are weathered and transported to the river by water flow. During the impact, collision and friction of the water flow in the river, they gradually turn into smooth pebbles.

2. Experimental observation: Use pliers to hold a stone and heat it on an alcohol lamp. Then immediately put the hot stone into cold water. Repeat several times to see what changes happen to the stone? What does it mean?

Answer: Stones will develop cracks and eventually break. This shows that cracks and fractures will occur after the rock expands due to thermal expansion and contraction.

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Update Time: 2024-09-09

This template belongs to science courseware E-education edition sixth grade science volume 1 industry PPT template

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