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

Perennial Saline Lakes

Perennial saline lakes are common in tropical and subtropical regions with relatively low rainfall. They include:

• Soda lakes (trona: Na₂CO₃.HNaCO₃.2H₂O)
• Sulphate lakes (mirabilite: Na₂SO₄.10H₂O)
• Chloride lakes (halite: NaCl)
• Nitrate lakes (Chile salpeter: NaNO₃)

Ephemeral Lakes

Ephemeral lakes form in dry regions where seasonal effects and evaporation play an important role in the sedimentation pattern. They include:

• Playa lakes
• Salt pans
• Oxbow lakes

Sub-Environments and Processes

Stratification

As the upper water layer is heated by the sun, an exponential temperature curve is expected in lakes, but this is seldom the case due to various factors. Evaporation at the surface cools the uppermost layer and produces convection currents,... Continue reading "Lake Environments: Types, Processes, and Sedimentation" »

Environmental Challenges: Spain & Global Resources

Biodiversity Defined

Biodiversity, or biological diversity, refers to the number and variety of species within a specific spatial area. Spain holds the distinction of being the European Union country with the greatest biodiversity.

Understanding Climate Change

Climate change is primarily driven by human actions, notably the greenhouse effect and the depletion of the ozone layer. Chlorofluorocarbons (CFCs) in the atmosphere attack the ozone layer, leading to an increased incidence of ultraviolet and infrared radiation from the sun. These factors contribute to a rise in the Earth's average temperature, posing significant risks such as melting ice caps, rising sea levels, and the submersion of... Continue reading "Global Environmental Challenges: Resources & Conservation" »

What is Soil? An Introduction to Pedology

Soil is the interface between the geosphere, biosphere, and atmosphere. The study of soil is known as Pedology (Soil Science).

Soil Formation: The Three Stages

Soil formation is a complex process divided into three main stages:

Stage 1: Formation of the C Horizon

Rocks experience both chemical and physical weathering, leading to a more or less altered bedrock. This altered material is also known as the mantle of alteration or the C horizon.

Stage 2: Development of the A Horizon

This stage involves the establishment of a progressive living horizon, with contributions from:

• Pioneer settlers (lichens, mosses, etc.)
• Microorganisms and heterotrophic organisms
• Higher plants and animals

These organisms contribute to... Continue reading "Understanding Soil: Formation, Properties, and Conservation" »

Global Health Challenges

Emerging and Re-emerging Infectious Diseases

According to the WHO (World Health Organization), from the onset of AIDS to SARS (Severe Acute Respiratory Syndrome), the rate of new infectious diseases has been approximately one per year. These emerging diseases are often transmitted by unknown pathogens. Some of these germs have long been confined to their natural habitats before coming into contact with humans. This is believed to have occurred with devastating hemorrhagic fevers such as Ebola.

Other cases involve re-emerging diseases, where major infectious diseases of the past, dangerous to the human species, have resurfaced due to mutations. Some of these recrudescent diseases are now affecting regions of the world where... Continue reading "Disease Emergence and Flood Impact: Global Challenges" »

Raw Materials and Industrial Inputs

These resources are offered by nature and are processed by industry to turn them into finished products. Depending on their source, raw materials can be classified into:

Classification of Raw Materials

• Mineral Raw Materials

  These are part of the Earth's crust. They are extracted from underground mines, which can be subterranean or open pit. Minerals can be classified as metallic (from which metals are extracted), non-metallic, and energy minerals (which provide energy sources).

• Vegetable Raw Materials

  Examples include food products, forest products, and rubber.

• Animal Raw Materials

  Examples include wool, hides, and fish.

Sources of Energy

Energy sources are mainly divided into two groups:

• Non-renewable energy sources:

... Continue reading "Classification of Raw Materials and Global Energy Sources" »

Precipitation

According to the process leading to their formation:

Orographic Precipitation

Terrain features, such as mountains and ridges, act as fixed screens and barriers. These force moist, warm air masses to rise. Consequently, this results in an adiabatic process that culminates in condensation and precipitation.

Convective Precipitation

Convective precipitation results from the warming of soil or water and the air in contact with it. This warm, moist air rises because its density is less than that of the upper layers. In doing so, it undergoes an adiabatic process that leads to condensation and rain.

Cyclonic Precipitation

A cyclone is an enormous mass of air that spins at very high speeds around a vortex. It is formed by strong temperature... Continue reading "Precipitation Types and Measurement Methods" »

Surface Water Resources and Management

Surface water bodies are the most important source of water supply. A prominent feature of these resources is their variability, which is highly dependent on irregular rainfall patterns.

Rivers: Characteristics and Flow Regime

The river network in Spain (approximately 70,000 km) often carries a relatively small volume of water, and its flow rate is highly irregular. Furthermore, rivers receive large volumes of spills, resulting in many contaminated sections.

Factors Characterizing River Flow

The river regime is characterized by several factors:

1. Flowrate: The amount of water flowing through a river at one specific point. It is measured in m³/s.

Flow = A · P · v

Irregularity: The ratio between the average annual... Continue reading "Surface Water Management: Rivers, Reservoirs, and Quality" »

We frequently use the word energy. In the late nineteenth century, science endorsed this concept and gave it a more precise meaning. Many properties of matter can be used to define different kinds of energy that can transform into each other and transfer from some bodies to others.

Kinetic and Potential Energy

An object in motion can collide with another and produce changes. This is known as kinetic energy and can be expressed mathematically as: E_c = 1/2mv². An object located at a certain height may fall, start moving, and push another. This is gravitational potential energy, and we can write it as: E_p = mgh.

Energy Conservation

Energy is conserved in any transformation. If an object falls from a height, it loses potential energy, but that energy... Continue reading "Understanding Energy: Forms, Conservation, and Sources" »

Understanding Earth's Landforms

Fluvial Landforms: Shaped by Water

• Furrows and Ravines

  These are trails formed by wild waters, causing grooves that group together and deepen. Increased concentration of water flow and erosion widens and deepens these grooves, forming gullies or ravines.

• V-shaped Valleys

  In mountainous regions, the river deepens its channel, increasing both width and depth, creating a characteristic 'V' shape.

• Trough Valleys

  The river erodes the channel walls above its bed, moving materials through gravitational processes, leading to a wider, U-shaped valley.

• Alluvial Fan

  An accumulation of material eroded and transported by a stream, deposited upon reaching flatter areas.

• Flood Plains

  Deposits formed by rivers during flood events. They

... Continue reading "Earth's Dynamic Landforms: A Compendium of Geological Features" »

Bacteria

Ecological Importance

In ecosystems, some bacteria fix free nitrogen from the atmosphere, incorporating it into host plants where it is converted into organic compounds.

Economic Importance

Bacteria are widely utilized by humans in various industrial processes. Certain species are essential for the production of cheese, butter, yogurt, and other dairy products.

Sanitary Significance

Most bacteria are benign and contribute to processes that benefit humans. However, some pathogenic bacteria can cause serious illnesses.

Blue-Green Algae (Cyanobacteria)

Ecological Significance

These algae are widely distributed, forming part of phytoplankton. They are primary producers in food chains and an essential foundation of life in seas, lakes, and lagoons.... Continue reading "Biological Kingdoms: Essential Roles and Human Impact" »