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

Planetary Origins and Earth's Structure

1.1 The Formation of Earth

Our solar system was formed from a solar nebula, or cloud of gas and dust, that collapsed and condensed about 4.56 billion years ago.

Most of this matter compacted together to form the Sun, while the remainder formed planets, asteroids, and smaller bodies.

Terrestrial vs. Jovian Planets

The outer planets—Jupiter, Saturn, Uranus, and Neptune—condensed at cold temperatures and are made mostly of hydrogen and helium. In contrast, the terrestrial planets (Mercury, Venus, Earth, and Mars), formed closer to the Sun, contain large amounts of iron, silicates (silicon and oxygen), magnesium, and other heavier elements that condense at high temperatures.

About 4 billion years ago, conditions... Continue reading "Planetary Formation, Geologic Time, and Earth's Core Composition" »

1. Non-Ferrous Metals and Their Alloys

1.1 General Non-Ferrous Metals

• Medium Melting Temperature: Cu, Ni
• Low Melting Temperature: Zn, Cd

1.2 Light Metals

• Medium Melting Temperature: Al, Mg, Be
• Low Melting Temperature: Li, Na

1.3 Noble (Precious) Metals

• Medium Melting Temperature: Ag, Au
• High Melting Temperature: Ru

1.4 High Melting Temperature Metals

• BCC Lattice: W, Ta
• HCP Lattice: Ti, Zr

1.5 Rare Earth Metals

• Trace Metals: Sc, Y, La
• Lanthanides: Ce, Pr

1.6 Radioactive Metals, Transuranides, and Transactinides

• Naturally Occurring Radioactive Metals: Po, Fr
• Transuranides and Actinides: Np, Pu
• Transactinides and Superactinides: Rf, Db

Metal Purity Levels:

• Raw Metal: 3-5% of impurities
• Technically Pure Metal: Up to 1% of impurities (fluxing)
• Electrolytically Refined

Proctor Compaction Test

1. Obtain air-dry soil on which the compaction test is to be conducted.

2. Sieve the soil.

3. Add enough water.

4. Determine the weight of the Proctor mold + base plate.

5. Attach the extension to the top of the mold.

6. Pour the moist soil into the mold in three equal layers.

7. Remove the top attachment from the mold.

8. Using a straight edge, trim the excess soil above the mold.

9. Determine the weight of the mold + base plate +- compacted moist soil in the mold, W2 (lb).

10. Remove the base plate from the mold. Using a jack, extrude the compacted soil cylinder from the mold.

11. Take a moisture can and determine its mass, W3 (g).

12. From the moist soil extruded in Step 10, collect a moisture sample in the moisture can (Step... Continue reading "Proctor Compaction Test Procedure and Equipment" »

Models of the Earth's Interior

Geochemical Model

• Crust: Up to the Mohorovičić discontinuity (35 km)
  • Continental: Granite and gneiss
  • Oceanic: Basalt
• Mantle: Up to the Gutenberg discontinuity (2,900 km). Composed of peridotite.
• Core: Central sphere (up to 6,378 km). Composed of iron and nickel.

Geodynamic Model

• Lithosphere: Crust and upper mantle. Composed of solid rocks.
  • Continental: 100–200 km (less dense)
  • Oceanic: 50–100 km (more dense)
• Asthenosphere: Solid but plastic rocks. Up to 660 km.
• Mesosphere: Solid but plastic rocks. Up to 2,900 km.
• Endosphere (Core):
  • Outer core: Up to the Lehmann discontinuity (5,100 km). Molten rocks.
  • Inner core: Remainder of the core. Solid rocks.

Isostasy

The behavior of the Earth's crust, as if it were floating on denser... Continue reading "Earth's Internal Structure and Geological Processes" »

Understanding Water Pollution

Water pollution is any chemical, physical, or biological change in water quality that has a damaging effect on anything living that consumes that water. When humans drink contaminated water, they often have health problems. Water contamination can also make it unsuitable for its intended use.

Common Types of Water Pollutants

There are several kinds of water pollutants. The first of these are disease-causing agents. These include bacteria, viruses, protozoa, and parasitic worms that are incorporated from sewage systems and raw sewage.

Oxygen-Consuming Agents

A second category of water pollutants are oxygen-consuming agents; these are residues that can be decomposed by oxygen-consuming bacteria. When the bacterial populations... Continue reading "Impacts and Causes of Water Contamination" »

Sunspot

The most visible manifestation of solar activity.

Solar Activity

All the sunspots, bursting events, and associated phenomena.

Solar Cycle

The nearly periodic 11-year change in solar activity (i.e., changes in the number of sunspots, flares, and other associated manifestations).

Wolf Number

A measure of the amount of sunspots, used to quantify solar activity.

Solar Wind

Solar material flowing into interplanetary space; the Sun's atmosphere expanding radially outwards in all directions.

Climate Change

A change in the statistical distribution of weather patterns.

Weather

The state of the atmosphere at any given place and time.

Climate

The average (mean) of weather parameters over a long period of time.

Meteoroid

A small rocky or metallic body traveling... Continue reading "Essential Astronomical and Meteorological Definitions" »

The Wilson Cycle: Earth's Dynamic Plate Movement

The Wilson Cycle describes the cyclical opening and closing of ocean basins and the fragmentation and reassembly of continents through plate tectonic processes. It typically involves several stages:

1. Continental Fragmentation and Rift Formation

   Plate dynamics generate tension that can cause a large continental mass to fracture along an axis. As the separation of plates continues, the lithosphere sinks, forming an intercontinental rift valley.

2. Formation of an Expanding Ocean

   If the rift is near a sea, the valley will flood, and a narrow sea will be formed. As the plates continue to separate, a mid-ocean ridge develops along the center, and new oceanic lithosphere expands.

3. Ocean Reduction and Continental

Structure of the Earth

Earth consists of four concentric layers: inner core, outer core, mantle, and crust. The crust is made up of tectonic plates, which are in constant motion. Earthquakes and volcanoes are most likely to occur at plate boundaries.

Inner Core

The inner core is in the center and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures reaching 5,500ºC.

Outer Core

The outer core is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. Temperatures are similar to the inner core.

Mantle

The mantle is the widest section of the Earth, with a thickness of approximately 2,900km. It is made up of semi-molten rock called magma.

Crust

The crust is the outer layer of... Continue reading "Structure of the Earth and Plate Tectonics: A Comprehensive Guide" »

What is the Environment?

We can define the environment as the space in which some kind of natural exchange that makes life possible takes place. The environment is not only the space itself but also the different forms of life that inhabit it. That is, if we were speaking of space only, we would be referring merely to a spatial location. On the other hand, the concept of environment expands this idea to include everything related to life developing in that space. Today, the environment is a topic very much in vogue because of the debate generated around its care and how human activity contributes increasingly more rapidly to damage it.

The environment is nothing other than the medium, precisely the place or space in which different life-related... Continue reading "Defining the Environment and Understanding Human Impact" »