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

Properties of Minerals

Loads of things are made of minerals. Rocks are a mixture of minerals and minerals are a mixture of chemical elements. Every mineral has properties. A mineral has the physical properties (you can see from the outside): colour, shape, size, shine, hardness, cleavage (how does the mineral break). And it also has the chemical properties (you can’t see from the outside): carbon dioxide…(minerals). Crystals can form from freezing and cooling, and we know that because the video shows us that if you mix sugar (or magnesium sulphate as we did in the lab which are crystals already) with hot water, and then we cool the water down we will obtain a bigger crystal. This process is called re-crystallization. The video also teaches... Continue reading "Understanding Minerals and Rocks: Properties, Formation, and Uses" »

Tunnel Typology

General Tunnel Classifications

• True tunnels: Typically constructed by boring or mining.
• Cut-and-cover tunnels: Involve slope excavation and the construction of retaining walls, with the tunnel then covered.
• Submerged tunnels: Constructed underwater, often by sinking pre-fabricated sections.

Classification by Ground Type

• Soft ground tunnels: Require specialized soft excavation techniques and robust support systems.
• Rock tunnels: Involve hard rock excavation methods and typically require moderate support.

Classification by Purpose

• Without inner pressure: Examples include hydraulic, railway, road, pedestrian, and hybrid tunnels.
• With inner pressure: Such as pressure galleries where the ground's stiffness significantly influences design and

Coastal Landforms: Erosion and Deposition

Headlands and Bays

Cliffs and Wave-Cut Platforms

Hello, we are going to talk about landslides. For us, this is really a massive natural disaster because it has a strong impact on all aspects, like the environment, the economy, and security. It is important to know about them because, basically, they can happen anywhere in the world. But first of all, what is a landslide?

Understanding the Causes of Landslides

It's important to understand the causes of this natural disaster because often people think that natural disasters are caused by supernatural forces. For example, in Mexico, some people believe that earthquakes happen in the month of September. Similarly, with landslides, some people think they are caused by a punishment from God or because Mother Nature is angry, but this is completely... Continue reading "Understanding Landslides: Causes and Impacts" »

Eutrophication

Eutrophication is the increase in nutrients, which increases the number of producers. This makes the water cloudy and prevents photosynthesis from taking place in the deeper levels, as there is a lack of sunlight. Heterotrophic organisms and decomposers intensify their activity, as there is more organic matter available. They also increase their oxygen consumption. In the end, the oxygen in the deeper level runs out, making it impossible for most species to survive.

Theory of Continental Drift

1912-1960: 225 million years ago, all the continents were joined together as one large supercontinent called Pangea. Over a very long period, the continents drifted apart to the positions they are today.

Evidence for Continental Drift

• Geological:

Landform Modeling: Earth's Dynamic Surface

Landform modeling refers to the changes caused to rocks in the Earth's crust by various geological agents. The characteristics of these changes vary significantly based on several factors:

Factors Influencing Landform Characteristics

• Climate of Each Region: Determines which geological agents act predominantly in an area.
• Type of Rock Arrangement: Not all rocks are equally resistant to modeling processes.
• Exposure: All exposed surfaces are subject to the same modeling agents.
• Vegetation: Land covered by vegetation is less exposed to modeling and is protected from precipitation.

Key Geological Processes

• Erosion: Modeling agents crack rocks, break fragments, and cause the gradual wearing away of the Earth's relief.

Energy Sources

Energy is the ability of a system to do work. Chemical: stored energy contained in chemical compounds. Released during chemical reactions, electrical: produced by the flow of electric charge, thermal: released as heat, electromagnetic: stored in electromagnetic waves or radiation, mechanical: combination of two energies (kinetic: things in motion, potential: stored within an object), nuclear: stored in the nuclei of atoms (fission: nucleus splits, fusion: nucleus joins).

Non-Renewable Energy Sources

Non-renewable energy sources are limited energy resources obtained from beneath the Earth. They are being used faster than they can be replenished. Fossil fuels are formed from the remains of microorganisms, plants and animals buried... Continue reading "Understanding Energy Sources: Renewable vs Non-Renewable" »

Secondary Sector and Energy Sources

The secondary sector includes all activities that convert raw materials into finished or semi-finished products. The secondary sector is usually associated with industry.

Crafts

When we talk about the secondary sector, it is important to remember crafts. In this type of work, products are made by hand or using small tools. Craftspeople work in a workshop and use materials such as fabric, glass, or clay.

Energy Sources

Energy sources are natural resources that produce the power required to make products from raw materials. There are two types: non-renewable energy sources, obtained from fossil fuels; and renewable energy sources, obtained from inexhaustible, non-polluting resources.

• Non-renewable: coal, petroleum,

Rigid Retaining Structures

Rigid structures have a rigid and stiff body. They move as a unit.

Types of Rigid Structures

• Gravity Walls

  These walls rely on their mass to resist lateral earth pressure.

  • Designed to avoid sliding and overturning.
  • Examples: In situ concrete walls, Masonry walls (often requiring drainage between the bricks), Rockfill.

• Cantilever Walls

  These walls use a structural stem and base slab to resist pressure.

  • Saves concrete compared to gravity walls.
  • Requires steel reinforcement.
  • Examples: Precast concrete walls, Green retaining walls.

• Counterfort Walls

  These walls use vertical supports (counterforts) connected to the stem and base.

  • The counterforts help support the bending moments.
  • Often used with reinforced earth (geosynthetics).
  • A toe

Hydropower

Hydropower utilizes the energy of water in rivers, which can be dammed to create reservoirs. These reservoirs have exit gates that lead to a turbine. The rotation of the turbine is converted into electricity. Reservoirs also serve to store water for irrigation and human consumption, and they help prevent dangerous floods.

However, hydropower has drawbacks. It can:

1. Inundate large areas of the banks.
2. Destabilize deltas (sediment that nourished these is now trapped at the bottom of the reservoir, and the sea erodes the delta).
3. Alter aquatic life.

Consequently, new hydropower plants are no longer built in many countries, and some older ones are being dismantled in more advanced nations.

Nuclear Energy

Globally, there are 442 nuclear power plants... Continue reading "Sustainable Energy Sources: Hydropower, Nuclear, Wind, and Solar" »