Earth's Structure: Layers and Composition

Layers of the Earth

• The Earth consists of three layers: crust, mantle, and core.
• The crust is made of rocks and minerals, with much of it covered by water, sand, soil, and ice.
• Bedrock, a solid rock, lies beneath the loose surface layer.
• The crust accounts for less than 1% of Earth's mass.
• Oxygen, magnesium, aluminum, silicon, calcium, sodium, potassium, and iron make up 99% of the Earth's crust.
• Continents are about 35 km thick, while ocean floors are about 8 km thick.
• The mantle lies below the crust, is about 2,900 km thick, and makes up about 70% of Earth's mass.
• The mantle consists of silicon, magnesium, oxygen, aluminum, and iron, with temperatures between 500°C and 2,000°C.
• The core lies in the center of the Earth and accounts for about 30% of Earth's mass.
• Molten iron and nickel primarily make up the outer core, which is about 2,200 km thick and has temperatures between 4,000°C and 6,000°C.
• Solid iron and nickel make up the inner core, which is about 1,270 km thick, due to extreme pressure, and its temperature reaches up to 7,000°C.

Slow Processes that Change the Surface of the Earth

• Weathering, erosion, and deposition are examples of slow processes that cause surface changes to the Earth.

Weathering

• Weathering is the process where a rock is broken down into smaller pieces on the Earth's surface.
• The three types of weathering are physical, biological, and chemical.
• Physical weathering, also called mechanical weathering, breaks down rocks without changing their chemical composition and is mainly due to temperature changes.
• In cold areas, weathering involves water, and when water freezes in cracks of rocks, it expands and widens the cracks.
• Rocks are broken down into pieces over time through the process known as ice wedging.
• Biological weathering occurs through the contribution of living things, such as roots growing into cracks and burrowing animals.
• Chemical weathering involves chemical reactions, where acidic rainwater reacts with minerals in rocks.

Erosion

• Erosion is the process of transporting broken rocks and soil materials by natural agents such as running water, waves, glaciers, and wind.

Deposition

• Deposition occurs when the movement of sediments slows or stops, causing the sediments to drop and creating landforms.

Non-Renewable Energy Sources

• Non-renewable energy sources will not replenish quickly and may run out soon, with most being fossil fuels formed from organic matter decay over 300 million years ago.
• Coal, petroleum, and oil shale are the types of fossil fuels currently in use and are made into fuels for different kinds of equipment and are used in manufacturing.

Coal

• Today's coal began to form millions of years ago in swampy areas from plant matter covered by layers of sediments.
• The intense heat and pressure converted the plant matter into a mixture of carbon and hydrocarbon compounds.
• Bituminous and anthracite coal are the oldest types, containing the highest carbon content, which makes them good for fueling power plants.
• Sub-bituminous and lignite coal are the youngest types, containing less carbon, which makes them less useful as fuels.
• Coal comes in different forms and is used to produce electricity, with coal beds located near the ground's surface for easier mining.
• Coal is also used in steel manufacturing, with a refined substance from it called coke used to smelt iron.

Petroleum

• Petroleum is formed over millions of years from decaying algae and tiny ocean animals known as plankton.
• The sediments and organic matter are buried deeper into the Earth, under pressure and heat, to become oil-bearing shale and crude oil.
• The bituminous deposits that include crude oil, natural gas, and tar are made into fuels for different kinds of equipment and are used in manufacturing.
• Petroleum is a major source of energy for transportation and is refined by fractional distillation into gasoline, diesel, and kerosene.
• Oil products are also used as raw materials in the manufacture of plastics.

Oil Shale

• Oil shale refers to sedimentary rocks containing solid bituminous materials (kerogen) that release petroleum-like liquid when heated by pyrolysis.
• Oil shale formed over long periods from silt and organic debris, with its oil unable to be pumped directly out of the ground, and currently, its extraction is more expensive than from conventional oil wells.

Disadvantages of Using Fossil Fuels

• The supply of fossil fuels is limited, as they do not replenish themselves and take millions of years to form.
• Combustion of fossil fuels releases carbon dioxide, a greenhouse gas responsible for global warming.
• It also releases carbon monoxide, nitrogen oxides, sulfur oxide, and heavy metals, causing pollution and acid rain.

Reducing the Negative Impact of Fossil Fuels

• Lowering fossil fuel consumption can be done by conserving energy, carpooling, and practicing the 3Rs (reduce, reuse, recycle).
• Increasing fuel efficiency requires ensuring efficient fuel combustion and using energy-efficient appliances.
• Using renewable energy such as the sun and wind offer reliability, lower costs and a small environmental impact.

Renewable Energy Sources

• Renewable energy sources can be replaced after being used, such as the Sun, wind, running water, waves, biomass, heat within the Earth, and hydrogen.

The Sun

• The Sun provides heat and light energy, and devices collect solar energy for water heating or convert it directly into electricity.
  • Advantages: Free of pollution and low maintenance cost
  • Disadvantages: High initial cost, weather dependence, and expensive energy storage.

Wind

• Wind can turn the blades of large windmills to produce electricity or pump water.
  • Advantages: Free of pollution and Low maintenance cost
  • Disadvantages: Not consistent, High installation costs, Threat to aerial animals

Running Water

• Hydroelectric energy uses the energy released when water rushes from a dam into a turbine.
  • Advantages: Reliable and efficient, Flexible flow control, Recreation and tourism attraction
  • Disadvantages: Environmental impact, displacement of people floods, expensive construction, limited locations

Waves

• Wave energy can be captured using special floating devices.
  • Advantages: Free of pollution, Relatively consistent and predictable, Low operation cost
  • Disadvantages: High cost of investment, Difficult to transmit, May disturb vessels

Biomass

• Biomass is the organic materials that come from plants and animals.
  • Advantages: Widely available, Cheaper than fossil fuels, Reduces landfills
  • Disadvantages: Not entirely clean, risk of Deforestation, Large space is needed.

Heat from inside the Earth

• Geothermal energy is derived from heat beneath the Earth's surface.
  • Advantages: Free of pollution, Constant supply
  • Disadvantages: May release greenhouse gases, High investment costs, Ground instability, Location specific

Hydrogen

• Hydrogen energy is converted into electricity using a fuel cell.
  • Advantages: Free of pollution, More powerful and high efficiency
  • Disadvantages: Expensive, Difficult to transport, Dangerous to use.