Rocks and Petrology Quiz

Weathering and Soil Formation

• Weathering: The breakdown of rocks into sediments through physical and chemical processes.
• Soil Formation: Involves the interaction of weathered materials with organic matter and biotic factors.

Difference between Sedimentation and Lithification

• Sedimentation: Encompasses weathering, transport, and deposition of materials.
• Lithification: Refers to compaction and cementation, transforming unconsolidated materials into consolidated rock.

Types of Rocks

• Petrology: Study focusing on rock composition, structure, and origin.
• Igneous Rocks: Formed from solidification of molten materials.
  • Most abundant in Earth's crust (approx. 95%).
  • Intrusive Igneous: Slow cooling, coarse texture (e.g., granite, gabbro).
  • Extrusive Igneous: Rapid cooling, fine texture (e.g., basalt, rhyolite).
• Sedimentary Rocks: Formed from compaction and cementation of sediments, can originate from biological materials (e.g., coal).
• Metamorphic Rocks: Form from existing rocks altered by heat and pressure (e.g., limestone to marble).

Rock Cycle

• Represents continuous transformation of rock types (igneous, sedimentary, metamorphic) over geological time.

Abundant Elements in Earth's Crust

• Oxygen (46.6%)
• Silicon (27.72%)
• Aluminum (8.13%)
• Iron (5.00%)
• Calcium (3.63%)
• Sodium (2.83%)
• Potassium (2.59%)
• Magnesium (2.09%)
• Other elements (1.41%)

Minerals and Mineralogy

• Minerals: Naturally occurring inorganic substances with a defined structure and composition (e.g., kaolinite).
• Mineralogy: Study of mineral structures and properties.

Weathering Processes

• Physical Weathering: Breakdown by physical forces (e.g., freeze-thaw, thermal expansion).
• Chemical Weathering: Alters minerals through chemical reactions (e.g., hydrolysis, oxidation).
• Biological Weathering: Involves living organisms facilitating rock breakdown (e.g., root wedging).

Soil Definition and Horizons

• Soil: A natural body composed of minerals, organic matter, liquid, and gases, distinguished by horizons.
• O Horizon: Organic layer, various decomposition stages.
• A Horizon: Topsoil enriched with organic material.
• E Horizon: Zone of eluviation, lighter in color due to leached materials.
• B Horizon: Subsoil, accumulation of leached materials.
• C Horizon: Partially weathered parent material.
• R Horizon: Unweathered bedrock.

Factors of Soil Formation (CLORPT)

• Climate: Affects weathering rates and soil formation.
• Organic matter: Contributes to nutrient availability and soil structure.
• Relief/Topography: Influences erosion and sediment deposition.
• Parent Material: Base material from which soil develops.
• Time: Duration impacts horizon development and soil maturity.

Soil Horizonation and Processes

• Horizonation: Differentiation of initial materials into distinct soil profiles through processes like eluviation and illuviation.
• Pedoturbation: Soil mixing involving organisms and environmental factors.

General Processes of Soil Formation

• Addition: Enrichment through organic and inorganic inputs.
• Removal: Erosion and leaching processes leading to material loss.
• Transformation: Decomposition, synthesis, and mineralization affecting soil composition.

Key Soil Concepts

• Concretions: Compact, cemented masses of mineral matter in soil.
• Hectare Furrow Slice: A measure representing soil mass for agricultural assessments.### Soil Terminology
• Pedon: The smallest unit of soil that can be recognized as an individual, influenced by activities of plants, animals, humans, and physical processes such as freeze-thaw cycles and leaching.
• Polypedon: A collection of multiple homogeneous pedons, forming a larger soil unit.

Soil Composition and Processes

• Saprolite: Chemically weathered rock that remains in situ; retains the structure of the original rock.
• Hardening: A process leading to a reduction in the volume of voids caused by collapse, compaction, and the filling of voids with materials like fine earth and carbonates.

Soil Horizons and Profiles

• Soil Horizon: A layer parallel to the soil surface characterized by unique physical, chemical, and biological properties that differ from adjacent layers.
• Soil Profile: A vertical section that shows all soil materials altered by chemical, physical, and biological processes; made up of distinct soil horizons.

Soil Chemical Changes

• Salinization: The buildup of soluble salts, including sulfates and chlorides of calcium, magnesium, sodium, and potassium, commonly found in salic horizons.
• Alkalization/Solonization: The process of sodium ion accumulation on exchange sites within the soil.
• Dealkalization/Solodization: The leaching process that removes sodium ions and salts from nitric horizons.
• Podzolization/Silication: Involves the chemical movement of aluminum and iron, contributing to soil profile development.

Transitional Horizons

• Transitional Horizon: A layer that exhibits characteristics of two distinct horizons, with one horizon being more dominant (for example, an AB horizon where characteristics of A are more pronounced than B).