Notes, summaries, assignments, exams, and exercises for Geology for Secondary education

Energy Inside the Earth

Temperature in the Earth's Interior

Although the surface is cold, scientists have calculated that at 2000 km depth, the temperature exceeds 2500 °C, and in the Earth's core at 6300 km, it is about 4500 °C.

Consequences of Heat Loss

The Earth radiates heat outwards as magma. Magma is formed by molten rock found at high temperatures. When it reaches the surface, it forms volcanoes.

Volcanoes

What are Volcanoes?

Volcanoes form when magma rises to the surface. During eruptions, explosions occur, which expel gas from the magma.

Materials Emitted by Volcanoes

In eruptions, volcanoes emit:

• GASES: Help the lava escape.
• LAVAS: Liquid rock ejected by volcanoes.
• Pyroclastic materials: These are classified as: bombs (reaching up to 30 cm)

Energy: Definition and Fundamental Principles

Energy: Power in action and the ability of a body to do work. Two principles: energy is neither created nor destroyed — it is only transformed, and it can change from a dispersed to a more concentrated form.

Kinds of Energy and Power Sources

Kinds of energy:

• Mechanical energy (water mill)
• Electromagnetic energy (generator)
• Thermal energy (coal combustion)
• Chemical energy (airplanes and batteries)
• Wind energy (windmills)
• Nuclear energy (fission)

Power sources: Any material or natural phenomenon from which we obtain energy. The amounts available from a source determine the energy resource.

Nuclear Energy: Features and Considerations

Features: Nuclear energy relies on fission reactions in atoms that release...

Historical Beliefs About Earth's Shape

Humanity has long believed that the Earth was flat. The sea surface appears to be horizontal, and so do the great plains of the continents.

Images taken from spacecraft show an Earth-shaped sphere. But the idea existed long before these ships were available; earlier observations seemed to confirm that fact.

The Greek philosopher Aristotle made early observations supporting a spherical Earth.

Horizon and Celestial Observations

On clear days you can see how boats disappear over the horizon. Sometimes you see the Earth's shadow projected on the Moon. It is always circular in shape, which is the type of shadow produced by a sphere. As we move north or south, we see new stars appear and others disappear from view....

Seafloor Spreading

By 1960, it was established that the composition of the ocean floor is primarily basaltic. Mid-ocean ridges are areas where new oceanic crust is created. Seafloor basalts are older the further they are from the ridge; their age is highest near continents and minimum along the ridge itself. The rate of expansion is estimated at a few millimeters per year. Seismic surveys revealed that it is not just the crust, but the entire lithosphere, that moves via convection currents.

Banded Magnetic Seabed

The Earth's magnetic field is unstable, and its polarity reverses periodically, causing the magnetic poles to swap positions. Currently, the north magnetic pole is in the Antarctic region, and the south magnetic pole is in the Arctic....

Landscapes, Erosion, and Sedimentation

Landscape: A portion of land characterized by biotic, anthropogenic, and atmospheric elements.

Erosion: The removal of materials by geological agents, resulting in wearing and modeling of the land.

Transportation: The movement of materials by geological agents.

Sedimentation: The accumulation of material in depressed areas of the surface (sedimentary basins).

Physical Weathering

Rupture of rocks due to tensions arising from different processes:

• Gelifraction: The action of water expanding when it freezes, causing cracks within the rock.
• Thermoclasty: Rupture of rocks exposed to sunlight.
• Decompression: The expansion and cleavage that occurs in rocks formed at depth.

Chemical Weathering

Disintegration of rocks due...

Energy Density of Non-Renewable Resources

• Wood: 14,000 kJ/kg
• Coal: 30,000 kJ/kg
• Oil: 40,000 kJ/kg
• Natural gas: 1 m³ equals 0.9 kg of oil
• Uranium: 1 g is equivalent to 1.7 metric tons of oil
• Deuterium: 1 g is equivalent to 7.4 metric tons of oil

Natural Gas and Nuclear Energy

Natural gas: A mixture of methane and other hydrocarbons. It has high power and low-polluting energy, generating CO₂ and water. Spain has significantly increased its use.

Nuclear energy: The energy source is uranium-235, used in nuclear fission reactors. It can also be fueled by plutonium, an element that is derived from uranium. Natural uranium cannot be used directly as fuel because it has a very small proportion of uranium-235; therefore, it must be enriched until it is at...

Causes of Climate Change

Fossil Fuel Combustion

The anthropogenic burning of fossil fuels, including coal, natural gas, and petroleum, is a primary process for electric power production and is directly linked to transportation. These activities are essential for human and industrial development but contribute significantly to greenhouse gas emissions.

Deforestation

The reduction of forest areas significantly impacts the equilibrium concentration of carbon dioxide in the atmosphere due to two principal reasons:

1. Burning vegetation releases methane and other greenhouse gases.
2. Trees, which make up forests, absorb large amounts of carbon dioxide through photosynthesis. Their removal reduces this natural carbon sink.

Impacts of Climate Change

Rising Sea

Energy Transfer in Trophic Chains

Photosynthetic organisms capture light energy from the sun that reaches the Earth's surface. These producers use this energy to perform photosynthesis, producing organic matter rich in energy from inorganic compounds.

Thus, light energy is converted into chemical energy and stored in the organic matter of the producers.

From One Link to the Next

What happens to the organic matter manufactured during photosynthesis?

• Respiration: A portion of the energy is degraded through respiration, used for the organism's vital functions, and released into the environment as heat.
• Waste: Parts of the organism, such as old leaves or roots, become waste and go directly to the decomposers.
• Stored Energy: The rest is stored in organs

Forces and Their Deforming Effects

A force can produce a deformation in a body. Experience shows that the distorting effect of a force depends on its intensity and the area on which it acts.

Understanding Fluids and Their Properties

Effects of Forces on Fluids

Substances called fluids are characterized by their ability to flow, even passing through small orifices. They do not have a definite form but conform to that of the container they occupy. Both liquids and gases are classified as fluids. A key distinction is that liquids are generally difficult to compress, while gases are highly compressible.

Principles of Pressure in Fluids

Pascal's Principle

Pascal's Principle states that the pressure exerted on any point of a confined incompressible fluid...

Historical Ideas on Earth's Age

• 1650: Archbishop James Ussher

  Anglican Archbishop James Ussher published a study that fixed the creation of the Earth in 4004 BC, precisely at 9 pm on October 23.

• Until the 18th Century

  The accepted age of the Earth was less than 6,000 years. This is known as short chronology or biblical chronology because it was based on a literal interpretation of the Bible.

The Answer Lies in the Rocks

Everything began to change in the 19th century when it was discovered that the past was preserved in the rocks. From this point, scientists attempted to "decipher" the geological code.

Reconstructing the Geological Past

Geologists seek answers to three fundamental questions:

1. What happened?

   Identifying the major events that have affected