"Diverse Surface Forms" Changes in the Earth's Surface PPT Courseware 2

"Diverse Surface Forms" Changes in the Earth's Surface PPT Courseware 2

former surface

What did the earth's surface look like in the past?

Answer: In the past, the earth was a vast ocean.

Why did the previous earth surface change to the current earth surface?

It is depicted as having two processes: enlargement and reduction. Expansion occurs when two plates move away from each other and magma from below forms new crust. Shrinking occurs when two plates collide, with the edge of one extending underneath the other and being heated and destroyed by the hot mantle. There are many faults at plate boundaries (such as the San Andreas Fault in California), and collisions between continental plates (such as the Indian Ocean Plate and the Eurasian Plate).

What is orogeny?

It refers to the movement in which local forces on the earth's crust cause the rocks to deform rapidly and cause large-scale uplift to form mountains. It affects only a narrow strip of the earth's crust. It is fast, large-amplitude, and wide-ranging, often causing huge changes in terrain levels; at the same time, with the strong deformation of rock strata, there are also horizontal displacements, forming complex folds and fracture structures. Folding and faulting, magmatic activity and metamorphism are the main signs of orogeny. The world's volcanic belts are consistent with island arc orogenic belts. The geosyncline is an unstable area of ​​the earth's crust, distributed in a band. It descended strongly in the early stage and deposited huge thick rock series. In the later stage, it folded and rose violently, forming a tall mountain system, that is, a fold belt. Geosynclines often surround or separate platforms in the form of narrow strips. Modern plate tectonics theory believes that the geosyncline is the edge part of the plate. The movement of the plate causes adjacent plates to squeeze and collide, forming island arcs and mountain systems. The mountains or bird arcs are the boundaries of the plates. This movement is manifested in the landforms as tall mountain systems, chain island arcs and associated deep ocean trenches, such as the Himalayas and the western Pacific island arc belt.

How many parts did the earth's surface consist of in the past?

The Earth's crust is made up of several solid plates, each floating on the hot mantle. Theoretically it is called plate theory. There are currently eight major sections:

¤North American Plate - North America, Northwest Atlantic and Greenland

¤South American Plate - South America and Southwest Atlantic

¤Antarctic Plate - Antarctica and coastal areas

¤Eurasian Plate - Northeast Atlantic, Europe and Asia except India

¤African Plate - Africa, Southeast Atlantic and Western Indian Ocean

¤Indian and Australian Plate - India, Australia and most of the Indian Ocean

¤The Nazca Plate - the eastern Pacific and parts of adjacent South America

¤Pacific Plate – most of the Pacific Ocean (and the southern coast of California)

There are more than twenty small plates, such as the Arabian and Philippine plates. Earthquakes often occur at these plate boundaries.

Summarize

In the early days of the earth's formation, when the earth cooled down, the surface of the earth was a vast ocean. After the later orogeny, land and mountains were formed. Then came the emergence of life. Life was born in the sea and evolved on land. , multiplied and evolved into many species, and the current surface was formed after the action of various natural forces, such as sunlight and weathering.

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"Diverse Land Surface Forms" PPT courseware on changes in the land surface:

"Diverse Land Surface Forms" Land Surface Changes PPT Courseware Teaching Objectives (1) Knowledge and Skills Read the map and understand the basic characteristics of my country's terrain. Process and methods Group cooperative learning and discussion analyze the impact of terrain on my country's climate, rivers and the production and life of our people ..