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

Carbon Cycle

The main reservoir of carbon is the atmosphere, but water also contains small amounts of CO2. Atmospheric CO2 is fixed by producers through photosynthesis. Consumers and decomposers incorporate carbon through food. Carbon can escape the cycle and remain separated from living beings, such as when fossil fuels are formed.

Nitrogen Cycle

The atmosphere is composed of 78% nitrogen, but this gas is inaccessible to most living things except bacteria. Consumers and decomposers incorporate nitrogen through food. Atmospheric nitrogen can be transformed into nitrates, which can leave the cycle when transported by water to sediment, where they form sedimentary rocks.

Homeostasis in Ecosystems

Homeostasis is the set of self-regulatory mechanisms... Continue reading "Carbon, Nitrogen Cycles & Ecosystem Dynamics Explained" »

Atmospheric Pollution

The combustion of hydrocarbons, largely due to industrial processes or transportation, generates smoke, suspended particulates, and gaseous pollutants. The most common are carbon monoxide, carbon dioxide, sulfur oxides, nitrogen oxides, and hydrogen sulfide.

Industrial facilities and power plants usually emit a greater volume of contaminants. In the developed world, the danger of some issues has forced the relocation of industries to industrial belts outside of densely populated urban areas. However, emissions are still causing serious environmental problems.

Acid Rain and Smog

Emissions of sulfur and nitrogen react in the atmosphere when in contact with oxygen, water vapor, and light, producing mainly sulfuric acid and nitric... Continue reading "Atmospheric Pollution and Environmental Degradation: Causes and Effects" »

Physical Properties of Oil

Color: Varies from yellow to reddish-brown. The color darkens with increasing specific gravity, which increases with the percentage of asphalt.

Odor: Varies depending on the amount of light hydrocarbons and impurities. Examples include a pleasant smell of petrol to an unpleasant odor similar to combustion.

Specific Weight: Oil is lighter than water. Its weight is influenced by factors such as the percentage of asphalt.

Viscosity: Depending on the specific gravity and chemical composition, oil can be either very fluid or viscous.

Solubility: Insoluble in water; due to its lighter weight, it remains on the surface. It is soluble in benzene, ether, chloroform, and other organic solvents.

Chemical Properties of Oil

Crude oil... Continue reading "Understanding Oil: Physical, Chemical Properties and Types" »

Equilibria in a Dynamic Planet

The water cycle, powered by solar energy, involves a series of ocean currents called the ocean conveyor belt. This cycle depends on the Earth's climate. The movement of mantle material causes the elevation of depths, which feeds volcanoes. These gases are composed of carbon, nitrogen, and sulfur, which are essential for the climate and the biosphere. Usually described as cycles, these are rather complex exchanges among many deposits. These flows and cycles form a very dynamic system.

Geological Risks and Hazards

Risk is the interaction of a geological process with human resources or assets. Risk depends on hazard (the probability of a phenomenon occurring) and damage (exposure and vulnerability).

Flooding and Flash

Understanding Cavitation in Fluid Dynamics

Cavitation, sometimes referred to as suction vacuum, is a hydrodynamic effect that occurs when water or another liquid fluid passes at high speed over a sharp edge, producing a fluid decompression due to the conservation of the Bernoulli constant (Bernoulli's Principle). It can reach the vapor pressure of the liquid so that its constituent molecules immediately change to a vapor state, forming bubbles or, more correctly, cavities. The formed bubbles travel to areas of higher pressure and implode (the vapor suddenly returns to a liquid state, abruptly collapsing the bubbles), producing a trail of gas and potentially damaging the metal surface where this phenomenon occurs.

Discharge Cavitation Explained

Discharge... Continue reading "Cavitation and Water Hammer Phenomena in Fluid Systems" »

Natural Hazards

Floods

Floods are common hazards often caused when heavy rainfall exceeds the soil's absorption capacity, leading to surface runoff. Aquifers, which are bodies of water found below ground, may be circulating or remain stagnant.

The risk of flooding depends on two factors:

• Precipitation type: There is a major risk if too much water falls in a short time.
• Orography of the land: The danger increases in low-lying areas and decreases at higher elevations. Thus, we predict that low areas (valleys) in regions with heavy rainfall are at higher risk.

Flow rate: This is the maximum level of water a river can reach during periods of peak precipitation. In these circumstances, the river overflows its banks, flooding the surrounding areas.

Crustal

Ocean Surface Currents and Wind Patterns

Surface currents are produced by the frictional force that winds exert on the ocean surface, reflecting the direction of prevailing winds. The Trade Winds blow from east to west, while the Westerlies blow from west to east.

The Mechanics of Marine Currents

These currents originate where water swirls in gyres, turning clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere. As the Earth rotates eastward, these vortices are deflected to the west. Upon colliding with continents located on the western side of the ocean basins, the currents are forced to narrow and intensify.

Major Warm Currents

The two major warm currents are:

• The Gulf Stream
• The Kuroshio Current

Effective Water Saving

Urban Drainage Master Plans

A master plan involves a set of studies for the planning of urban drainage in a city (study area) over a period of time, considering its interaction with external contributing basins and receiving streams. These plans are designed to maintain hydraulic order.

Drainage System Components

A drainage system typically includes:

• The main collector and its discharge works to a main channel or another collector.
• Branches and tributaries.
• Inspection and cleaning chambers.
• Sinks (inlets) that capture runoff from roads, e.g., Zanjón de la Aguada.

Collectors can be in open channels or underground.

Key Hydraulic Structures

Dams and Reservoirs

A reservoir is a body of work consisting of a dam that closes a natural channel. An embankment... Continue reading "Urban Drainage & Water Systems: Key Infrastructure" »

Earthquake Causes, Effects, and Prevention

Causes of Earthquakes

• Regional-Global Scale: Lithospheric subduction zones (cause of large earthquakes).
• Local Causes:
  • Volcanic eruptions
  • Escape of materials related to large surface currents
  • Fractures
  • Fluid extraction: groundwater, petroleum
  • Excavation collapse: mining, filling of reservoirs

Effects of Earthquakes

• Shaking of soil and buildings (the majority of deaths are caused by the collapse of buildings).
• Ground displacements taking place across fault lines.
• Landslides (a violent earthquake can trigger thousands of them).
• Tsunamis or tidal waves (traveling at high speed).
• Explosions: nuclear tests, exploration for mineral and oil deposits, mining operations.

Increased Seismic Risk Factors

• Human overpopulation

Geographic Coordinates and Earth's Geometry

• Poles: The extreme points of Earth's diameter that form the axis of rotation.
• Equator: The circle of the Earth perpendicular to the line of the poles.
• Great Circle: The intersection of a sphere with any plane passing through its center.
• Earth Meridians: Great circles that pass through Earth's poles and cross the Equator perpendicularly.
• Local Meridian: The terrestrial meridian passing through a specific place; any meridian is divided by the poles into two equal parts of 180°.
• Greenwich Meridian: Passes through the observatory of the same name; it is also called the 0° meridian or Prime Meridian.
• Parallels: Smaller circles that are parallel to the Equator.

Maritime Navigation and Port Data

Port of Valparaiso:... Continue reading "Essential Geographic and Maritime Navigation Terms" »