Physical Geology and Engineering Applications

Vocabulary terms and definitions covering the branches of geology, weathering processes, wind-related landforms, groundwater characteristics, and seismology as presented in Module 1.

Engineering Geology

An applied science which deals with the application of geology for a safe, stable, and economic design and construction of a civil engineering project.

Physical Geology

Also known as dynamic geology or geomorphology, it deals with physical features of the earth, surface changes, natural phenomena like earthquakes, and the geological work of wind, glaciers, and water.

Mineralogy

The study of minerals, which are the basic units of rocks and ores, including their formation, composition, properties, and uses.

Petrology

The study of rocks, including their mode of formation, structure, texture, composition, and occurrence in the earth's crust (lithosphere).

Structural Geology

The study of geological structures caused by tectonic forces, such as folds, faults, joints, and unconformities.

Stratigraphy

Also called historical geology, it is the study of the earth's history through the investigation of sedimentary rock layers (strata).

Economic Geology

The study of minerals that have economic value, such as talc, graphite, diamond, and gems, focusing on their formation, occurrence, and uses.

Mining Geology

The application of geological knowledge to the field of mining, including the exploration and estimation of ore bodies.

Geophysics

The study of the physical properties of the earth, such as density and magnetism, to understand its interior.

Geohydrology

Also known as hydrogeology, this field deals with the occurrence, movement, and nature of groundwater.

Geochemistry

A branch dealing with the occurrence, distribution, abundance, and mobility of different elements in the earth's crust.

Weathering

The process of decay, disintegration, and decomposition of rocks under the influence of physical and chemical agencies.

Disintegration

The process of breaking up rocks into small pieces by the mechanical actions of physical agents.

Decomposition

The process of breaking up mineral constituents to form new components through chemical actions.

Denudation

A general term used for when the surface of the earth is worn away by chemical and mechanical actions, exposing lower rock layers.

Physical Weathering

The physical breakdown of rock masses into smaller fragments and particles under the attack of atmospheric agents like temperature variations.

Exfoliation

A process where rock breaks off into concentric shells due to unequal expansion and contraction caused by temperature fluctuations.

Spheroidal Weathering

A type of weathering that leaves residual boulders with an onion-like structure.

Chemical Weathering

The chemical decomposition of rock through reactions between atmospheric gases (like $CO_2$) and rock minerals, typically in the presence of water.

Wind

The movement of the atmosphere in a direction parallel to the earth's surface.

Deflation

A wind erosion process that involves removing loose sand and dust-sized particles from an area.

Abrasion

Wind erosion where wind-loaded particles rub and grind rock surfaces, often creating pedestal or mushroom rocks.

Bed Load

Larger and heavier particles, such as sands or gravels, moved by wind but not lifted more than $30$ to $60\,cm$ above the surface.

Suspended Load

Fine clay or dust particles lifted by moving winds to a distance of hundreds of meters above the earth's surface.

Aeolian Deposits

Sediments dropped and deposited by wind, including sand dunes and loess.

Barchans

Crescent-shaped or new-moon-shaped sand dunes with a steep side facing away from the wind direction.

Loess

Massive deposits formed by the accumulation of the finest dust particles transported in suspension by the wind.

Connate Water

Water entrapped in the interstices of sedimentary rock at the time of its deposition.

Juvenile Water

New water of magmatic, volcanic, or cosmic origin added to the terrestrial water supply.

Aquifer

A permeable geologic formation with a structure that permits appreciable water to move through it under ordinary field conditions.

Aquitard

A partly permeable formation through which only seepage is possible, yielding insignificant water compared to an aquifer.

Aquiclude

An impermeable formation that may contain water but is incapable of transmitting significant quantities.

Aquifuge

An impermeable formation that neither contains nor transmits water.

Porosity

The amount of pore space per unit volume of aquifer material, expressed as the percentage of void space to the total volume.

Permeability

The capacity of a rock to permit the flow of water through its pores, determined by factors such as pore size.

Seismology

The science dealing with the study of earthquakes in all their aspects.

Focus

The exact spot underneath the earth's surface at which an earthquake originates.

Epicenter

The point on the surface immediately above the focus or origin of the earthquake.

Anticenter

The point on the earth's surface that is diametrically opposite to the epicenter.

Intensity (Earthquake)

A rating of an earthquake based on the actual effects produced by the quakes on the earth's surface.

Magnitude (Earthquake)

A rating based on the total amount of energy released when over-strained rocks suddenly rebound.

Tectonic Earthquake

A disastrous type of earthquake caused by folding or faulting of the layers of the earth's crust.