Earth's Structure and Layers

Study Notes

Structure of the Earth

The Earth's outermost layer is the crust, divided into continental crust (thicker and less dense) and oceanic crust (thinner and more dense).
The mantle is the layer below the crust, extending to about 2,900 km deep, and is composed of silicate rocks rich in magnesium and iron.
The Earth's core comprises the outer core (liquid, mostly iron and nickel) and the inner core (solid, primarily iron).
The Mohorovičić Discontinuity (Moho) marks the boundary between the Earth's crust and the mantle, with a sudden increase in seismic wave velocities.
The Gutenberg Discontinuity marks the boundary between the mantle and the outer core, with a significant decrease in seismic wave velocities.
The Lehmann Discontinuity marks the boundary between the outer core and the inner core, with an increase in seismic wave velocities.

Plate Tectonics

The lithosphere is the rigid outer layer of the Earth, broken into tectonic plates.
The asthenosphere is the semi-fluid layer beneath the lithosphere on which tectonic plates move.
Divergent boundaries are where plates move apart, such as at the Mid-Atlantic Ridge.
Convergent boundaries are where plates move towards each other, such as at the Himalayas.
Transform boundaries are where plates slide past each other, such as at the San Andreas Fault.

Major Landforms

Mountains are elevated areas formed by tectonic forces, such as the Himalayas.
Valleys are low areas between mountains or hills, often with rivers.
Plateaus are elevated flat areas.
Plains are broad, flat, or gently rolling areas.
Deserts are dry areas with sparse vegetation, such as the Sahara Desert.
Coastal landforms include beaches, cliffs, and dunes.

Hydrosphere

Oceans cover about 71% of the Earth's surface.
The major oceans are the Pacific, Atlantic, Indian, Southern, and Arctic.
Rivers are large natural streams of water flowing towards oceans, seas, or lakes, such as the Amazon and Nile.
Lakes are inland bodies of water, such as Lake Superior and the Caspian Sea.
Glaciers are large ice masses that move slowly over land, such as the Greenland Ice Sheet.

Atmosphere

The troposphere is the lowest layer of the atmosphere, where weather occurs.
The stratosphere contains the ozone layer.
The mesosphere is where meteors burn up.
The thermosphere is where auroras occur and contains the ionosphere.
The exosphere is the outermost layer, merging into space.
The tropopause marks the boundary between the troposphere and the stratosphere.
The stratopause marks the boundary between the stratosphere and the mesosphere.
The mesopause marks the boundary between the mesosphere and the thermosphere, and is the coldest point in the atmosphere.
The thermopause marks the boundary between the thermosphere and the exosphere.

Climate and Weather

Climate zones include tropical, temperate, and polar regions.
Tropical climates are near the equator, warm year-round.
Temperate climates have moderate temperatures, with distinct seasons.
Polar climates are near the poles, cold year-round.
Cyclones are large-scale air masses that rotate around a strong center of low atmospheric pressure.
Tornadoes are violently rotating columns of air in contact with both the surface of the Earth and a cumulonimbus cloud.
Hurricanes are intense tropical storms with powerful winds and heavy rain.

Biosphere

Biomes are large regions characterized by specific climate, flora, and fauna, such as rainforests, deserts, and tundras.
Ecosystems are communities of living organisms interacting with their physical environment.
Biodiversity is the variety of life on Earth, crucial for ecosystem stability and resilience.

Description

Learn about the composition of the Earth, including the crust, mantle, and core, and their distinct characteristics. Explore the differences between continental and oceanic crust, and the primary discontinuities from the outermost layer to the inner core.