Geology for Engineers: Understanding Weathering

Physical weathering = Caused by changing temperature on rocks, breaking them apart Chemical weathering = Involves breakdown of rock by acidic water to produce clay and soluble salts Biological weathering = Breakdown of rocks by biological activity such as plant roots Mechanical weathering = Breakdown of rocks without changing its chemical composition

Solution = Removal of rock in solution by acidic rainwater Hydrolysis = Breakdown of rock by acidic water to produce clay and soluble salts Oxidation = Breakdown of rock by oxygen and water, giving iron-rich rocks a rusty surface Carbonation = Weathering of limestone by rainwater containing dissolved CO2

Frost wedging = Rock breaking apart due to freeze-thaw cycles Thermal stress = Rock breaking due to temperature changes Salt crystal growth = Rock breaking apart due to salt expanding within its pores Biological weathering = Rock breaking down by roots of plants

Solution = Removal of rock in solution by acidic rainwater Hydrolysis = Production of clay and soluble salts from rock breakdown Oxidation = Giving iron-rich rocks a rusty-colored surface

Physical weathering = Occurs in places with little soil and few plants Chemical weathering = Caused by rain water reacting with mineral grains Hydrolysis = Chemical reaction of anything with water Freeze-thaw weathering = Water freezes and expands in cracks, breaking rocks apart

Freeze-thaw weathering = Mountainous regions like the Alps or Snowdonia Physical weathering in deserts = Expansion and contraction of surface rocks baked by the sun Physical weathering in mountains = Repeated melting and freezing of water Chemical weathering = Occurs especially in places with little soil and few plants

Hydrolysis = Chemical reaction of anything with water Acidic rainwater reaction = Forms new minerals like clays and soluble salts Mineral grain reaction = Rainwater reacts with mineral grains in rocks Soluble salts formation = Reactions occur when water is slightly acidic

Expansion-contraction in deserts = Surface rocks expand and contract due to sun exposure Freeze-thaw weathering = Water freezes and expands, causing rocks to split further open Repeated melting-freezing in mountains = Water repeatedly melts and freezes, leading to rock cracking Pressure reduction effect = Cracks develop parallel to land surface due to uplift and erosion

Chemical weathering = Involves the breakdown of rocks due to chemical reactions, such as oxidation or hydrolysis Physical weathering = Involves the breakdown of rocks into smaller pieces without any change in the chemical composition Biological weathering = Involves the breakdown of rocks by living organisms, such as plant roots or burrowing animals Solution weathering = Involves the dissolution of rocks by acidic water or other solvents

Limestone = Commonly weathered by solution due to its high solubility in acidic water Sandstone = Composed of sand-sized grains and often formed from the accumulation of sand dunes or beaches Mudstone = Consists of fine-grained particles and commonly formed in low-energy environments like lakes or deep ocean basins

Cold environment = Most likely to experience physical weathering processes due to freeze-thaw cycles Wet environment = Most conducive to chemical weathering processes due to higher levels of moisture facilitating reactions Dry environment = Less favorable for weathering processes, both physical and chemical, compared to wet environments

Land slips after heavy rain = Result of physical weathering caused by water-induced slope failures Mudflows after volcanic eruptions = Result of solution weathering where volcanic ash mixes with water to form lahars Wind erosion in dry regions = Example of physical weathering where wind transports and erodes soil and rocks Repaired road abandoned due to landslides = Result of physical weathering causing repeated slope failures in weak mudstones

Uplift = Process involving the movement of rock layers towards the Earth's surface, often leading to exposure and subsequent weathering Melting and crystallization of magma = Process where heat causes rocks to melt and solidify, leading to changes in mineral composition and texture Transport and deposition of sediment = Process where sediments are moved by natural forces like water or wind and deposited in new locations

Burial and compaction = Result in sedimentary rock formation through the accumulation, burial, and lithification of sediments Deformation and metamorphism = Lead to changes in rock texture, structure, and mineral composition due to high pressure and temperature conditions Weathering, erosion, and transport = Processes that break down rocks into sediments and move them to new locations for further deposition