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

HUMAN IMPACT

Acidic rain: It is a broad term that includes any form of precipitation with acidic components and results when dioxide (So2) and nitrogen oxides (NO) are emitted into the atmosphere and transported by wind and air currents. Acid rain is caused by the burning of fossil fuels to generate electricity, the chemical releases of vehicles and from manufacturing. There are two forms of acid rain: dry deposition which is crust in a sheltered area and wet depositions that are raindrops of sulphurous acid. Acid rain can be very harmful to the environment because it takes away minerals from the leaves and soil and without them plants cannot grow properly. Even if this rain doesn’t fall straight into lakes it can get there through rivers... Continue reading "Human Impact: Acid Rain, Climate Change, Overfishing, and More" »

EARTH INTERNAL LAYERS: Compositional : Crust (oceanic, continental) Mantle, Core. Phisical: Lithospere (rigid), Low velocity zone (ductile and partially molten), Lower molten (solid), Core (outer molten, inner solid).

 EV OF THE THEORY OF CONT DRIFT: Paleolithic evidence: Fossils. Biological ev: Living beings. Geological ev: Continents fit. Paleoclimatic ev: Glacier rests. BENIOFF ZONE: Area of seismic activity in a subducting plate. WILSON CYCLE: Rift Valley Stage: Magma rises up through fractures making the lithosphere thinner and lower. Red Sea St: Deep lakes are formed at the bottom of the valley, which spreads. Atlantic Ocean st: New oceanic lithosphere is being produced and the Atl Oc is expanding. Pacific Ocean st: The Oc lithosphere... Continue reading "Mnemonic for lithosphere,asthenosphere,mesosphere,outer core and inner core" »

Understanding Plate Tectonics and Earth's Geological Features

Key Concepts in Plate Tectonics

Alfred Wegener

Proposed the theories of continental drift and plate tectonics in 1912.

Continental Drift

The theory that Earth's continents have moved over geological time relative to each other, appearing to drift across the ocean bed; they were once joined together as a single supercontinent.

Plate Tectonics

The scientific theory that the Earth's outer rigid layer, the lithosphere, is broken into large, rigid pieces called tectonic plates that are in constant motion over the Earth's mantle.

Lithosphere

The rigid outer layer of the Earth, consisting of the crust and the uppermost part of the mantle. Tectonic plates are made of the lithosphere.

Asthenosphere

The

Weathering and Erosion

Weathering is the process which causes rocks and minerals to break down and disintegrate into smaller pieces. This can occur through chemical, biological, and mechanical processes influenced by temperature and humidity. Erosion by water forms gullies in the land, which can gradually deepen into ravines and gorges.

Landscapes and Tectonic Plates

Landscapes produced under the surface of the earth are known as karst landscapes. The solid part of the earth is divided into different layers separated by areas known as discontinuities, such as the Mohorovičić discontinuity, Repetti, Gutenberg, and Lehmann. Tectonic plates, made up of the crust and the upper mantle, are massive slabs of solid rock. Volcanoes are cracks or openings... Continue reading "Understanding Weathering, Erosion, and Tectonic Plates" »

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.