Notes, summaries, assignments, exams, and problems for Geology

The Rock Cycle

The eroded rock reliefs acquiesce.

In areas of collision, mountains arise, and rocks undergo a process of metamorphosis.

The succession of these phenomena is the rock cycle.

The surface rocks are altered by physical or chemical processes to form sedimentary rocks.

In the depths of the crust, in subduction zones, by varying the temperature and pressure, metamorphic rocks occur.

Igneous rocks are formed by the cooling of magma from the melting of solid materials from the mantle or crust. If cooling is slow, the structure of the rock is plutonic; if it's fast, it's volcanic.

Magmatism

Magmatism on the Ridges

There are cracks in the ridges where basaltic magma rises, which solidifies at the bottom of the sea.

Magmatism in Subduction Zones

In... Continue reading "Understanding the Rock Cycle, Magmatism, and Mountain Formation" »

The Birth of Earth

As the terrestrial protoplanet increased in volume, the gravitational pull exerted by the planetesimals that collided with it increased. In these violent clashes, a large amount of heat was released, causing the planet to become partially molten. This merger allowed the denser material to sink, forming the core, while the lighter gases moved outward to form the atmosphere. Intermediate-density materials rose to form the mantle. Once the surface cooled, the abundant water vapor in the atmosphere condensed, forming the oceans.

The Early Atmosphere

The early atmosphere is believed to have formed by the degassing of the planet's interior. It contained large amounts of carbon dioxide and water vapor, along with some nitrogen. The... Continue reading "Earth's Formation and the Emergence of Life" »

Geology: Understanding Our Planet and Solar System

Geology is the science that studies the composition, structure, origin, and evolution of the Earth and other celestial bodies within the solar system.

Origin of the Solar System

The solar system, approximately 4.5 billion years old, originated from a nebula. This nebula consisted of dust, hydrogen, helium, and trace amounts of other chemical elements.

The nebula underwent several distinct phases:

1. Condensation: A nearby supernova explosion destabilized the initial nebula. Attractive forces overcame repulsive forces, causing materials to condense. The concentration was highest at the center, forming a protosun (primitive sun).
2. Planetesimal Formation: Condensed materials collided, forming planetesimals.

Types of Effort:

• 1. Compression caused by opposing forces and convergent (crush)
• 2. Strain or tension (stretch) caused by opposing forces and divergent
• 3. Parallel shear force caused by divergent and convergent (rip)

The Rock Cycle: Rocks are always formed from earlier ones. The rock cycle is an example of interaction with internal and external phenomena:

• 1. Internal geological processes: magmatism and metamorphism caused by the heat of the Earth
• 2. External geological processes: transport, sediment erosion, weathering, and diagenesis caused by solar energy.

Agent of Erosion:

• 1. Weathering
• 2. Erosion
• 3. Sediment transport

Internal Processes:

• 1. Magmatism and plate tectonics: The internal heat causing the magma is known as the geothermal gradient. The rocks

Understanding Key Environmental and Ecological Terms

Upwelling: Ocean Dynamics Explained

Upwelling is the vertical movement of deep, colder, and denser water toward the ocean surface. It can occur for various reasons, one of the most frequent being wind on the ocean surface.

Purification: Stream Recovery Process

Purification is the process of recovering a stream after an organic pollution episode.

Biofuels: Renewable Energy Sources

Biofuels are fuels derived from biological sources, obtained in a renewable manner from organic waste. These usually come from organic remains of sugar, wheat, corn, or oilseeds.

Atmospheric Inversion: Temperature Anomaly

An inversion refers to an abnormal change in the properties of the atmosphere with increasing altitude.... Continue reading "Essential Environmental and Ecological Concepts" »

The Hydrosphere: Oceans, Seas, and Freshwater

The hydrosphere comprises the Earth's water. Oceans and seas account for 97% of this water, while freshwater makes up the remaining 3%.

Freshwater Distribution

Freshwater is distributed as follows: 78% in glaciers, 21% in subterranean sources, and 1% on the surface.

Key Properties of Water

Water possesses several unique properties:

• It is a good solvent.
• It absorbs large amounts of heat.
• Its thermal expansion (dilatation) is abnormal.
• It is adherent.

Ocean Water Movements

Ocean water exhibits three primary movements:

• Waves: Caused by wind.
• Currents: Movement of large water masses.
• Tides: The periodic rise and fall of sea levels.

The Water Cycle

The water cycle is the continuous set of steps and processes that water... Continue reading "Earth's Water, Minerals, and Rock Formations" »

Major Geological Processes: Erosion, Transport, and Deposition

Erosion: Material Evacuation and Relief Modeling

Erosion is the evacuation of material by geological agents, resulting in the wear of reliefs and karst modeling.

Effects of Erosion

• Evacuation of Debris: Fragments of rocks or clasts produced by weathering.
• Modeling Land Surface Characteristics: Geological agents move rock clasts, producing specific relief forms.
• Peneplain Formation: Large, virtually flat areas resulting from extensive erosion.
• Redistribution of Continental Masses: Erosion, sediment transport, and subsequent deposit in sedimentary basins cause weight loss in mountainous areas.

Transport: Conveyance of Geological Materials

Transport is the conveyance of materials by geological... Continue reading "Geological Processes: Erosion, Sediment Transport, and Deposition" »

Understanding Natural Resources

All elements of nature that can be utilized to meet human needs and ensure survival and well-being are defined as natural resources.

Classification by Regeneration Rate

Natural resources are primarily distinguished based on the time required for their formation or regeneration:

• Renewable Resources

  These resources can regenerate after use, provided their consumption rate does not exceed their regeneration rate. Examples include water and solar energy.

• Non-Renewable Resources

  These are resources that cannot be recreated or replenished once consumed. Examples include oil and coal.

• Inexhaustible Resources

  These resources are used by humans in very small amounts relative to their vast abundance in nature. An example is solar

Climate: Concepts and Parameters

Climatology is the science that deals with climate studies. Climate is a set of meteorological phenomena that characterize the situation and weather in a particular place on Earth. The climate is the result of a series of interactions between latitude, altitude, continentality, and prevailing wind patterns.

Precipitation

Precipitation is water falling on the Earth's surface in liquid or solid form. For precipitation to occur, clouds must first be formed. This happens in three different ways:

• Convective Precipitation: Caused by rising warm air.
• Orographic Precipitation: Occurs when moist air is forced to rise over mountains.
• Frontal Precipitation: Results from the interaction of different air masses along a front.

Types

Sedimentary Rocks: Formation & Characteristics

Sedimentary rocks are formed by the accumulation of sediments, subjected to physical and chemical processes (diagenesis), resulting in consolidated material.

Sedimentary Rock Texture Types

Clastic Texture

Clastic texture characterizes sediments formed by the mechanical accumulation of detrital particles. This texture is influenced by the size and shape of the original mineral and rock particles, or by the types of organisms whose skeletons or shells accumulate.

Non-Clastic Texture

Non-clastic textures are formed by chemical and organic substances.

Major Types of Sedimentary Rocks

Detrital Sedimentary Rocks

Detrital rocks are formed by the accumulation of debris from erosion and deposited by gravity.... Continue reading "Sedimentary Rock Formation: Types, Textures & Processes" »