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Key Words
Key Words
Crust, Mantle, Outer Core, Inner Core, Lithosphere, Asthenosphere, Convection Currents, Tectonic Plates, Plate Boundaries (Convergent, Divergent, Transform), Earthquakes, Volcanoes, Seafloor Spreading, Mountain Building.
Overview
Earth's structure is complex and fascinating, consisting of several layers, each with unique characteristics and functions. Understanding these layers helps us explore the planet’s geology, tectonic activity, and natural phenomena like earthquakes and volcanoes. This guide will provide an overview of Earth's layers and their significance in shaping the planet.
The Layers of Earth
The Layers of Earth
Earth is composed of four main layers:
Crust:
The outermost layer.
Thin and solid, varying between 5-70 km in thickness.
Composed of two types:
Continental Crust: Thick, less dense, primarily granite.
Oceanic Crust: Thinner, more dense, primarily basalt.
Contains landforms, rocks, and soil.
Mantle:
Located beneath the crust, extending to about 2,900 km deep.
Made of semi-solid rock.
Contains convection currents that drive tectonic plate movements.
Divided into:
Upper Mantle: Includes part of the lithosphere and asthenosphere.
Lower Mantle: More rigid due to increased pressure.
Outer Core:
A liquid layer composed of iron and nickel.
Responsible for generating Earth's magnetic field.
Extends from 2,900 km to 5,150 km below the surface.
Inner Core:
The innermost layer, composed of solid iron and nickel.
Extremely hot, with temperatures up to 5,500°C.
Solid due to immense pressure despite the high temperature.
The Lithosphere and Asthenosphere
The Lithosphere and Asthenosphere
Lithosphere:
Includes the crust and the rigid upper part of the mantle.
Divided into tectonic plates that float on the asthenosphere.
Asthenosphere:
The semi-fluid layer beneath the lithosphere.
Allows tectonic plates to move.
Convection Currents: The Driving Force
Convection Currents: The Driving Force
Within the mantle, convection currents occur as hot, less dense material rises, cools, and sinks again. These currents drive the movement of tectonic plates, influencing earthquakes, volcanic activity, and mountain building.
Plate Tectonics and Boundaries
Plate Tectonics and Boundaries
The movement of tectonic plates shapes Earth’s surface through interactions at plate boundaries:
Convergent Boundaries: Plates move toward each other, forming mountains or subduction zones.
Divergent Boundaries: Plates move apart, creating new crust at mid-ocean ridges.
Transform Boundaries: Plates slide past each other, often causing earthquakes.
Key Processes and Phenomena
Key Processes and Phenomena
Earthquakes: Sudden movements along fault lines caused by plate interactions.
Volcanoes: Openings in Earth's crust where magma, gases, and ash erupt.
Seafloor Spreading: Creation of new oceanic crust at divergent boundaries.
Mountain Building: Formation of mountains through plate collisions.
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