Soil Processes, Natural Resources, Geologic Materials & Corrosion – Lecture Review

Vocabulary flashcards covering soil processes, natural resources, geologic structures, rock types, and corrosion mechanisms discussed in the lecture.

Podzolization

Soil‐forming process in cool, humid climates where organic acids leach silica, aluminum, and iron downward, creating a bleached upper horizon and an accumulation zone below.

Gleying

Development of water-logged, bluish-gray soils under anaerobic conditions where iron compounds are reduced and removed, typical of marshy areas.

Desilication

Removal of silica together with bases from a soil profile, common in intensely weathered humid tropical regions.

Translocation (soil)

General movement of soil materials, predominantly downward, by processes such as leaching, eluviation, and illuviation.

Leaching

Downward transport of dissolved minerals by percolating water, especially where precipitation exceeds evaporation.

Eluviation

Washing out of clay, iron, or organic matter from an upper soil horizon, leaving it depleted.

Illuviation

Accumulation of materials leached from above, producing a distinct enrichment horizon.

Calcification

Soil process in semi-arid regions where calcium carbonate precipitates and accumulates in the profile.

Salinization

Build-up of soluble salts in soils, often where evaporation exceeds precipitation.

Soil Profile

Vertical section of soil showing horizons formed by weathering and pedogenic processes.

Humid Tropical Climate

Warm, high-rainfall environment that promotes intense weathering and ferralsol development.

Organic Matter (soil)

Decaying plant and animal residues; rapidly decomposed in sandy tropical soils, leading to low humus content.

Natural Resources Conservation

Holistic, sustainable stewardship ensuring continued provision of ecological goods and services.

Forest Resources

Complex ecological systems delivering timber, biodiversity, climate regulation, and water catchment functions.

Water Resources

Interconnected, dynamic hydrologic systems essential for domestic use, agriculture, and hydropower.

Biodiversity Reservoirs

Forests that house a significant portion of species, including endemics, maintaining ecological stability.

Water Catchment Forests

Upland forests in Kenya that supply most primary water for domestic, agricultural, and hydroelectric uses.

Ecological Powerhouse

Term highlighting forests’ wide range of quantifiable and non-quantifiable ecological values.

Engineering Geology

Branch of geology applying earth-science data to civil engineering problems such as site selection and slope stability.

Slope Stability

Resistance of a hillside or embankment to failure; controlled by rock type, structure, water, and human activity.

Fault (geologic)

Fracture in rock along which displacement has occurred, impacting foundations and slope design.

Fold

Bend in layered rocks formed by compressive forces, influencing tunnelling and reservoir siting.

Sedimentary Rock

Rock formed from accumulated sediments; may exhibit bedding, fossils, and graded structures.

Breccia

Coarse sedimentary rock composed of angular fragments cemented together.

Conglomerate

Clastic sedimentary rock with rounded pebbles and cobbles in a finer matrix.

Chert

Hard, microcrystalline silica rock often occurring as nodules or beds within limestone.

Gypsum

Evaporite mineral (CaSO₄·2H₂O) forming soft, whitish sedimentary layers.

Dolomite (rock)

Carbonate rock dominated by the mineral dolomite (CaMg(CO₃)₂).

Graded Bedding

Sedimentary structure where grain size fines upward, indicating waning current energy.

Fossil

Preserved remains or traces of ancient life found mainly in sedimentary rocks.

Metamorphic Rock

Rock altered by heat, pressure, or fluids, transforming original texture and mineralogy.

Gneiss

Banded, foliated metamorphic rock derived from high-grade metamorphism of granite or sedimentary protoliths.

Quartzite

Hard, non-foliated metamorphic rock from recrystallized sandstone rich in quartz.

Schist

Strongly foliated metamorphic rock with visible mica flakes, indicating medium-grade metamorphism.

Corrosion

Gradual deterioration of a material, usually metal, through chemical or electrochemical reaction with its environment.

Uniform Corrosion

Even, overall metal thinning across a surface; the most common corrosion type.

Galvanic Corrosion

Accelerated attack on a metal when electrically coupled to a more noble metal in an electrolyte.

Pitting Corrosion

Localized corrosion forming small cavities or ‘pits’ that penetrate deeply.

Intergranular Corrosion

Preferential attack along metal grain boundaries, weakening structural integrity.

Fretting Corrosion

Surface damage at contact areas subjected to repeated small oscillatory motion.

Microbial Corrosion

Material degradation caused or accelerated by the metabolic activity of microorganisms.

Weathering (intense)

Breakdown of minerals under warm, wet conditions, producing deeply leached, nutrient-poor soils.