Earth's Internal Structure, Rocks, and Soil Composition

Internal Structure of the Earth

• Continental Crust
• Mohorovicic Discontinuity
• Upper Mantle
• Transition Zone
• Lower Mantle
• Outer Core
• Inner Core

Soil Layers and Composition

• Core: Nickel and Iron
• Mesosphere: Silicon, Iron, and Magnesium
• Crust: Silicon and Magnesium

Rocks

Igneous Rocks

Formed from melted minerals, typically found in the Earth's core. They have an inlaid and laminated glass appearance. Examples include granite and sharpening stone.

Sedimentary Rocks

Formed at the bottom of lakes and oceans. They appear as a mass of different substances in layers. An example is gypsum.

Metamorphic Rocks

Formed from igneous or sedimentary rocks due to changes in temperature and humidity. They appear as attached blades that separate easily. Examples include slate and marble.

Lithosphere

The rock area of the Earth.

Minerals are inorganic matter.

Soil

Soil is a natural formation of varying thicknesses that allows the development of plants and animals. It is composed of a fraction of minerals, is porous, and allows for air and water penetration.

• Organic Fraction: Leaves, branches, and other organic matter.
• Mineral Fraction: Disintegrated rocks.

Physical processes form soil and sand, while chemical processes form clay.

Soil Properties

Soil is made up of particles of different sizes:

• Clay
• Silt
• Sand
• Gravel
• Pebbles

Soil Profile

• Horizon A: Organic matter accumulates, forming humus.
• Horizon B: Mineral layer, also contains some organic matter.
• Horizon C: Consists of rock debris from the disintegration of bedrock.
• Horizon R: The lowest layer, bedrock, which creates the other horizons.

Soil Classification

Rocky Soils

Lack Horizon A and B, are hard, impermeable, and have a dry appearance.

Sandy Soils

Porous and permeable, allowing water to pass through easily. They do not retain moisture.

Clay Soils

Soft texture, similar to sand, but maintain moisture and are less permeable.

Organic Soils

Rich in organic matter, porous, fluffy, fertile, and maintain moisture.

Topsoil

Optimal for agriculture, composed of organic matter.

Optimal Soil Composition for Agriculture

Clay Loam

Retains moisture and favors aeration. However, it is not suitable for all crops because water is absorbed quickly.

Sand and Gravel

Due to their porosity, roots receive enough air for oxygenation. However, they do not retain water and are dry and arid.

Essential chemical elements for agriculture include nitrogen, phosphorus, and potassium.

Erosion

A natural process that breaks down the soil. External agents include rain and wind. Examples of human-induced erosion include logging, indiscriminate irrigation, burning of forests, and indiscriminate planting.

Desertification

The process where wind carries sand from coastal and desert areas to farmland, destroying vegetation.

Soil Conservation

Soil Contamination

Any element that alters the composition of the soil.

Use of Pesticides

These are chemical elements that, if not properly managed, can remain in the soil for a long time. It is advisable to use pesticides that degrade easily.

Fertilizer Usage

Excessive use of fertilizers can cause eutrophication.