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

The Journey of Human Evolution

Unraveling Our Past: Prehistory and History

The story of human existence on our planet is filled with many chapters yet to be fully understood. In the quest for answers, a methodological division has been established, using the invention of writing as a pivotal milestone to separate prehistory from history. This distinction has, throughout the ages, brought forth a central question: the origin and evolution of humanity.

The term human evolution refers to the development of a lineage of ancestors, including various hominids and early Homo species, leading to modern humans. We, *Homo sapiens sapiens*, belong to the branch of modern humans, making our appearance on Earth approximately 40,000 years ago, though dating... Continue reading "Human Evolution: From Early Hominids to Modern Homo Sapiens" »

The Early Earth

The Earth formed approximately 4,600 million years ago, with temperatures exceeding today's by hundreds of degrees. These high temperatures were partly due to meteor impacts. The Earth's rock melted, and heavier elements like iron and nickel sank to the planet's center. This began a slow cooling and solidification of the outer layer. Elements combined to form various compounds. Almost all oxygen combined with hydrogen to form water, with carbon to form carbon dioxide, and with other elements (methane and carbon monoxide) to form minerals. After millions of years, the temperature dropped below 100°C, and steam clouds condensed, raining for hundreds of years to form slightly salty oceans.

Early Atmosphere

Scientists believe Earth'... Continue reading "Origin of Life: Earth's Early Conditions and Theories" »

Soybean Crop: Origin and Significance

Soy is of Asian origin. Today, it is one of the most important legumes in the country. In 1994, there were 184,056 hectares cultivated, with an annual production of 370,846 tonnes.

Climate and Soil Requirements

The appropriate temperatures range from a minimum of 12°C to 30°C.

Sowing Techniques

1. Prepare the soil thoroughly.
2. Select high-quality seeds.
3. The amount of seed varies according to the size of the seed. It may range from 65 kg for small seed varieties to 120 kg for large seeds, with an average of 2 bushels (92 kg).
4. Aim for a plant density of 400,000 to 900,000 plants per hectare.
5. Create furrows for planting with a distance of 60 cm between them. If planting in a line, sow 15 to 30 seeds per meter. The depth

Tectonic Dispositions

• Horizontal or Aclinal Relief: Self-sedimented areas with horizontal strata, alternating hard and soft layers. Water systems erode softer layers, creating residual relief.
• Monoclinal Relief: Gently sloping sedimentary areas with alternating hard and soft materials. Erosion forms steep slopes and isolated hills.
• Faulted or Germanic Structure: Results from pressure exceeding rock deformation capacity, leading to fractures, uplifted blocks, and sunken areas.
• Folded Relief: Formed by folding of sedimentary rocks due to compression. Anticlines are prone to erosion, while synclines retain more compact materials.

Appalachian Relief

Folded relief leveled by erosion, forming a base.

Jurassic Relief

Found in young mountain ranges with alternating... Continue reading "Understanding Landforms: Tectonics and Stress Factors" »

Fossil Fuels: A Deep Dive

Most of the energy used worldwide today comes from fossil fuels. They are used in transportation, to generate electricity, to heat rooms, and for cooking.

Fossil fuels include oil, coal, and natural gas, formed millions of years ago from the organic remains of dead plants and animals. Over millennia, the remains of organisms were deposited at the bottom of seas, lakes, and other water bodies, covered by layers of sediment. Chemical reactions of decomposition and the pressure exerted by the weight of these layers transformed these organic remains into gas, oil, or coal.

The Non-Renewable Nature of Fossil Fuels

Fossil fuels are nonrenewable resources; we cannot replace what we consume. They will eventually run out, and it... Continue reading "Fossil Fuels: Formation, Uses, and Future Availability" »

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" »

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" »

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" »