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

Types of Plate Boundaries

1) Constructive or Divergent Boundaries

Two plates move apart from each other. New magma rises to the surface, cools, and forms basalt, creating volcanoes and rift valleys.

2) Destructive or Convergent Boundaries

Two plates move towards each other. Typically, an oceanic plate sinks below the other in a subduction zone. Sediments between the plates fold, forming mountain ranges. Friction melts rocks, causing volcanoes and earthquakes.

3) Conservative Boundaries

Two plates slide against each other, often at different speeds. Stress buildup leads to sudden movements and friction, resulting in earthquakes.

Negative Impacts on People

Earthquakes

Earthquake shockwaves damage buildings, bridges, and roads, causing injuries and fatalities.... Continue reading "Understanding Plate Boundaries and Their Impact" »

Composition of Earth's Atmosphere

• Nitrogen (78%)
• Oxygen (20%)
• Argon (1%)

Greenhouse Gases

Examples: H2O, CO2, CH4, NO2, O3

Importance: Without greenhouse gases, Earth's temperature would be -22 to -36 degrees Celsius.

Greenhouse Effect

Solar energy absorbed by Earth and re-radiated as heat by greenhouse gases.

1. Natural Greenhouse Effect
2. Human-Induced Greenhouse Effect (Global Warming)

Global Warming / Climate Change

Caused by burning fossil fuels, deforestation, and human activities that increase carbon dioxide levels, leading to Earth's warming.

Ozone, Hole in Ozone, UV Rays, CFCs

Ozone

Located mostly in the lower stratosphere, it acts as a shield against harmful UV radiation from the sun.

Hole in the Ozone Layer

Causes: Primarily caused by human-made chemicals... Continue reading "Understanding Earth's Atmosphere and Climate Change" »

Coastal Erosion

Factors Influencing Wave Size and Energy

The size and energy of a wave are influenced by:

• How long the wind has been blowing
• The strength of the wind
• The fetch (the distance the wind blows over the surface of the water)

Rate of Coastline Erosion

The rate of coastline erosion is influenced by:

• Type of rock (e.g., chalk and limestone form steep cliffs)
• Strength of waves
• Speed of waves

Destructive Waves

Destructive waves are created in storm conditions. They are characterized by:

• Being created from big, strong waves when the wind is powerful and has been blowing for a long time
• Occurring when wave energy is high and the wave has traveled over a long fetch
• Eroding the coast
• Having a stronger backwash than swash
• Having a short wavelength and being

Volcanoes

Scenario: Consider a geographic location for a volcano. What type of plate setting is it located in? What kind of volcano is it (composite, dome, or shield)? What kind of lava does it produce (rhyolite, andesite, or basalt)? Is the lava predominantly silicate, feldspar, or ferromagnesian? Why? Is the lava felsic, mafic, or a combination in origin? Why? Describe the characteristics of a volcanic eruption.

Plate Tectonics:

• Divergent (mid-ocean ridges = volcanoes)
• Rift zones = volcanoes
• Subduction zones = volcanoes
• Hot spots = volcanoes

Lava

Composition:

• Result of the geologic setting, which determines available source material.
• Extent of melting, which determines what becomes the source material.
• A mix of SiO4, Al, Fe, Mg.

• Rich in SiO4: more felsic

Climate Feedbacks and Their Impact on Climate Change

Feedbacks within the climate system amplify climate changes initially caused by external factors. This can be visualized as:

• Initial climate forcing → Initial climate response → Response amplified

Example: An increase in heat energy sent to Earth by the Sun causes high-latitude snow and ice to retreat. This allows more sunlight to be absorbed by the Earth's surface, leading to further climatic warming (amplifying the changes underway). Another example is delayed bedrock rebound.

Negative Feedback Mechanisms in Climate Change

Initial climate changes can also lead to a reduced response:

• Initial climate forcing → Initial climate response → Response reduced

Example: Chemical weathering acts... Continue reading "Climate Change: Feedbacks, Processes, and History" »

Understanding the Greenhouse Effect

The greenhouse effect is a process in which thermal radiation emitted by the planetary surface is absorbed by atmospheric greenhouse gases and re-emitted in all directions.

Solutions to Mitigate the Greenhouse Effect

• Recycle paper.
• Decrease CO2 and methane emissions.
• Implement policies promoting sustainable resources in every country.
• Reduce the use of fossil fuels and use renewable fuels instead.
• Improve building infrastructure to use less energy and fewer non-renewable resources.

Changing Lifestyles for a Sustainable Future

• Only buy what is needed.
• Disconnect electronic equipment when leaving home.
• Conserve water.
• Consume fewer processed products.

Effects of Ozone Depletion

When the ozone layer is depleted, the ultraviolet radiations of the sun can reach the earth's surface in greater proportion. This results in damage to animal and plant life on the earth. Ultraviolet rays cause skin cancer and cataracts in human beings. The ozone hole is seen in the stratosphere above Antarctica.

Main Sources of Water Pollution

There are two main sources of water pollution: natural and manmade sources. They can be further categorized into various types. Mineral from land that are washed off due to heavy rains, dead animals, animal waste, ash, chemical after forest fires, sulfur compounds after an earthquake, etc. are natural sources of water pollution. City sewage and industrial waste are the manmade... Continue reading "Effects of Ozone Depletion, Water and Noise Pollution" »