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

Composition of the Atmosphere

• Nitrogen: 78%
• Oxygen: 21%
• Other: 1% (carbon dioxide, ozone)

Due to the pull of gravity, the atmosphere’s density decreases with altitude. Weather is directly related to air pressure, and the pressure of an air column on a body decreases as altitude increases.

Layers of the Atmosphere

Troposphere

Temperature: Decreases. This is the lowest, thinnest, and densest layer, containing 80% of the atmosphere's mass. Weather occurs here. The tropopause acts as a barrier between cold and hot air, and this is where airplanes fly.

Stratosphere

Temperature: Increases. Contains 19% of the air. Temperature rises because gas particles absorb solar radiation. It houses the ozone layer, which shields humans from ultraviolet radiation. Weather... Continue reading "Earth's Atmosphere Layers and Composition Explained" »

Raw Materials and Energy Sources

Types of Raw Materials

Raw materials are classified into three types: raw materials of animal and plant origin, and raw materials of mineral origin.

Non-Metallic Minerals

Non-metallic minerals are those from which other materials are obtained, including sulfur, rock salt, gypsum, and mica. Rocks are also considered non-metallic raw materials; rocks are also considered non-metallic raw materials. Mines and mining refer to the process of extracting raw materials of mineral origin.

Energy Sources

Non-renewable energy sources are natural resources that are processed to produce energy for domestic purposes and the operation of industries and transport. They are divided into two groups: depending on their economic importance,... Continue reading "Natural Resources and Medieval Spanish Literature" »

Energy Resources

Nonrenewable Energy

Nonrenewable energy is a source of energy that exists in limited quantities and, once used, cannot be replaced except over millions of years.

Examples:

• Coal (fossil fuel)
• Oil (fossil fuel)
• Natural gas (fossil fuel)
• Uranium (rock)

Renewable Energy

Renewable energy is a source of energy that can be replaced in a relatively short period of time.

Examples:

• Hydroelectric
• Solar
• Geothermal
• Wind
• Biomass
• Nuclear fusion (potentially in the future)

Most renewable energy originates from the sun.

Fossil Fuels

Oil, natural gas, and coal are known as fossil fuels because they were formed underground from the remains of once-living organisms. Fossil fuels are relatively inexpensive and are usually readily available, but their use creates... Continue reading "Renewable & Non-Renewable Energy Resources: A Comprehensive Guide" »

The Hydrosphere

Definition

All the water that exists on our planet is collectively known as the hydrosphere. This includes water found on the ground, surrounding us, and underground.

Forms of Water

• Solid: Ice, glaciers, snow, and ice caps.
• Liquid: Rivers, seas, oceans, and rain.
• Gas: Steam and water vapor.

Distribution of Water

• Planet: 71% water
• Marine Water: 97%
• Fresh Water: 3%

Water Uses

Water is essential for various purposes, including agriculture, industries, homes, public services, energy production, transportation, and recreation.

Waters of Mexico

Mexico's water resources include marine and fresh water, with diverse classifications, uses, and locations.

Marine Water

Mexico has a vast coastline with access to the Pacific Ocean, the Gulf of California,... Continue reading "Understanding the Hydrosphere, Atmosphere, and Climate" »

Seismic Portrait of Earth's Layers

Earth's layers are detectable as changes in seismic wave velocity with depth.

The boundary between the upper and lower mantle is visible at 660 km as a sudden change from rapidly increasing P- and S-wave velocities to slow or no change in P-wave and S-wave velocities.

The core-mantle boundary is apparent as a sudden drop in P-wave velocities, where seismic waves move from solid mantle to liquid outer core.

The boundary between the outer core and inner core is marked by a sudden increase in P-wave velocity after 5000 km, where seismic waves move from a liquid back into a solid again.

Crust–Mantle Boundary (Moho discontinuity)

Depth: Its depth is ~10 km under the ocean floor and ~35 km under the continents.

Discovery:

Radioactive Decay: Principles and Equations

If the decay rate is equal to λ, the probability that a given nucleus will decay in a small time interval dt is λdt. Therefore, if at any time we have P parent nuclei, the number that decay in the next moment is P(λdt).

The rate of change of parent nuclei (dP/dt) is proportional to the number of parent nuclei present:

dP/dt = -λP

This differential equation can be solved as follows:

• Separate variables: dP/P = -λdt
• Integrate both sides: ∫(dP/P) = -λ∫dt
• Resulting in: ln(P) = -λt + C

The boundary condition is found because we know that when t = 0, P = P₀ (the initial number of parent nuclei). Therefore, C = ln(P₀), and we can write the equation as:

ln(P) = ln(P₀) - λt

Rearranging this equation:

• ln(P)

Coastal Dynamics: Waves and Marine Erosion

Waves are fundamental forces shaping our coastlines. Their interaction with the shore involves two primary movements: swash and backwash.

Understanding Wave Dynamics

Swash and Backwash: The Basics

• Swash: When water rushes up the beach.
• Backwash: When water drains back down the beach.

Destructive Waves: Shaping Coastlines

Destructive waves are powerful forces that remove material from the beach. They are characterized by a weak swash and a strong backwash, pulling sand and pebbles back down the beach as the water retreats.

• Often steep, high waves that are close together.
• Crash down onto the beach.
• Come in very quickly, at a rate of 10 to 15 waves per minute.
• Also known as plunging waves.

Constructive Waves: Building

Coastal Erosion Processes and Hazards

Cliff erosion is a continuing process. Wave refraction causes eroding energy to wrap around jutting headlands, narrowing them and creating tombolos and offshore islands.

Site Selection and Construction Measures

1. Build 5 or more meters above normal high tide.
2. Build in a spot with numerous high dunes between the proposed building and the water.
3. Determine the rate of coastline erosion in the immediate vicinity.

Slope Stabilization Techniques

1. Reduction of slope angle.
2. Terracing.
3. Placement of additional supporting material at the base of the slope.
4. Removal of soil, rock, or artificial structures high on the slope to reduce the mass.

Signs of Slope Failure

1. Doors or windows stick or jam for the first time.
2. New cracks appear

Erosional Base and Graded Sand Units

Erosional base is in the head, and deposition is in the body.

Normal Graded Sand Unit (Ta)

Rapid deposition from suspension.

Planar Stratified Sand Unit (Tb)

Deposition on an upper stage plane bed, indicating flow deceleration, reduction of deposition rate, and establishment of a well-defined bed over which there was both bed load and suspended load movement.

Cross Laminated Ripple Unit (Tc)

Further decrease in flow velocity with an appreciable deposition rate.

The Overlying Planar Laminated Mud Unit (Td)

Deposition from the tail.

The Massive Mud Unit (Te)

Fallout from the turbulent buoyant plume.

Lakes: Palaeoclimate Indicators

Two key features of lakes:

1. They are among our best indicators of continental palaeoclimate.

Climograma

Un Climograma é un gráfico no que representamos simultaneamente os valores da temperatura media mensual, mediante unha liña, e os de precipitación media mensual, mediante barras verticais, dos doce meses do ano. No eixe vertical esquerdo situaremos as frecuencias de temperatura en oC (Graos Centígrados), tendo en conta se hai temperaturas inferiores a 0oC, pois nese caso haberá que deixar un espazo para representalas. As temperaturas medias mensuais están unidas por unha liña vermella 1.No eixe vertical dereito representaremos as precipitacións (en mm), tendo en conta as proporcións que debemos utilizar en función do total, sabendo que será necesario indicar o dobre do valor empregado no eixe vertical esquerdo. A diferenza... Continue reading "Climograma and Pollution: Environmental Impact in Spain" »