Weathering Processes in Geology

Weathering

• Weathering is the breakdown of rocks, minerals, and soil by physical, chemical, or biological processes.
• Physical weathering involves the disintegration of rocks into smaller pieces without changing their chemical composition. Examples include frost wedging (water expands in cracks), thermal expansion and contraction (temperature changes), and abrasion (rocks rubbing against each other).
• Chemical weathering involves the alteration of the chemical composition of rocks. This process frequently involves water, acids, or other chemicals that react with the minerals in the rock, such as oxidation (rust), hydrolysis (breakdown by water), and carbonation (reaction with carbonic acid).
• Biological weathering involves the role of living organisms in the breakdown of rocks. Examples include plant roots growing into cracks, burrowing animals, and acid secretions from fungi and bacteria.
• Rates of weathering are affected by climate (temperature, precipitation), rock type, and topography. Regions with high temperatures and rainfall tend to experience faster weathering.
• The products of weathering are transported away by erosion, contributing to soil formation and the creation of sediments.

Internal Heat

• Earth's internal heat is primarily derived from residual heat from planetary formation and radioactive decay within the Earth.
• The heat flow from the Earth's interior drives convection currents in the mantle.
• These convection currents are crucial for plate tectonics.
• The Earth's internal heat distribution varies with depth, generally decreasing with depth but with localized variations related to active geologically features such as volcanoes, mid-ocean ridges, and hot spots.
• Earth's internal heat is responsible for several geological phenomena:
  • Volcanism: Molten rock (magma) rises from the interior to the surface, forming volcanoes.
  • Plate tectonics: The movement of tectonic plates is driven by convection currents in the mantle.
  • Earthquakes: Movement along faults within the Earth's crust is caused by stresses created by the tectonic plates' movement. (In the case of heat related earthquakes, stress is accumulated due to local mantle activity.)

Geology

• Geology is the science that studies the Earth.
• It encompasses the processes that shape the Earth's surface and interior, including rock formation, plate tectonics, the movement of continents, and the history of life.
• Geology is divided into several specialties, including structural geology (study of rock structures like folds and faults), geochemistry (study of the chemical composition of the Earth), and sedimentology (study of sediments and sedimentary rocks).
• The study of the Earth's history, including both the physical changes and biological evolution, is referred to as Earth's history.
• Principles of relative dating and absolute dating help scientists understand the timing of events in the Earth's history.
• Minerals are naturally occurring solid substances with a specific chemical composition and crystalline structure. They are essential to understanding the formation of rocks.
• Rocks are aggregates of one or more minerals with varying properties (e.g. texture, color, composition) depending on the process involved in their formation.