| Category | Format | Size |
|---|---|---|
| Zhejiang Education Edition Seventh Grade Science Volume 1 | pptx | 6 MB |
"Plates on the Earth's Surface" PPT courseware
Description
"Plates on the Earth's Surface" PPT courseware
Part One: Evidence
fossil evidence
Glossary fern fossil ----- It is a fern that lived 250 million years ago. Scientists have discovered fossils of tongue ferns in Africa, South America, Australia, India and Antarctica.
Thoughts and discussions one
Glossary fern grows in warm to cool climate conditions, but Glossary fern plant fossils are widely distributed in Africa, South America, India, Australia, Antarctica and other continents, but the climate of these continents does not have such climatic conditions. This shows what?
It shows that these continents were once connected together, and that these continents may be located in warm and cooler latitudes, and then drifted and gradually drifted away from their original positions.
Topographic evidence:
There is a mountain range running from east to west in South Africa that connects with a mountain in Argentina. It was also discovered that the coastlines on both sides of the Atlantic Ocean corresponded to each other, and even the rocks and folds in the two places matched.
It shows that these continents were once connected together, but later drifted and gradually drifted away from their original positions.
climate evidence
Tropical plant fossils have been found on islands north of the Arctic Ocean, huge coal seams have been found in Antarctica, and glacial scratches have been found in South Africa.
This shows that these continents have drifted away from their original positions.
biological evidence
The two continents are far apart, but they have similar creatures.
It shows that these continents were once connected together, but later drifted and gradually drifted away from their original positions.
PPT on the plates on the earth's surface, part 2: various theories
continental drift theory
1. All mainland on the earth had a unified huge land before the middle generation.
2. The lighter silicon aluminum continent floats on the heavier sticky silicone magnesium layer.
3. Due to the effect of force, the continent ruptured and is separated from the silicon magnesium layer, and westward and the equator to a large -scale drift.
Thoughts and discussions 2
1. Why is the "continental drift theory" a scientific hypothesis?
2. What is the shortage of "mainland drift doctrine"?
seafloor spreading theory
Mantle material rises and gushes out from mid-ocean ridges and continental rifts. The outflowing mantle material condenses into a new ocean floor and pushes away the previously formed ocean floor, gradually expanding symmetrically to both sides. When the ocean floor expands and reaches the trench, it subducts downward and returns to the mantle.
Thoughts and discussions three
Does the "seafloor spreading theory" support the "continental drift theory"? What problem does it solve with the "continental drift theory"?
plate tectonics theory
1. The Earth's lithosphere is composed of six major plates, divided by trenches, ridges and huge mountains.
2. The plates "float" on the asthenosphere, constantly colliding and splitting with each other.
Student activities two
Operating requirements:
Place two books opposite each other, with the two books close to each other, then move the book toward the middle and observe carefully!
Student activities three
Take two wooden boards spliced together with newspaper paper, sprinkle some foam balls on the board, and pull the two people slowly in different directions until they break.
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Update Time: 2024-07-01
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