Balearic PAU Geology & Env Sci key terms

Rate at which temperature increases with depth inside the Earth, averaging about 25-30 °C per kilometre in the crust and driving metamorphism, magma generation and convection.

State of gravitational balance in which rigid lithospheric blocks float on the denser asthenosphere, so thicker or lighter crust stands higher, explaining mountain roots and post-glacial rebound.

Rigid outer shell of the Earth comprising the crust and uppermost mantle, broken into tectonic plates that move over the weaker asthenosphere beneath.

Weak, partially molten layer of the upper mantle below the lithosphere that deforms plastically and allows tectonic plates to slide horizontally over geological time.

Process by which only the lowest-melting minerals of a rock melt, producing magma richer in silica than its source; triggered by decompression, heating or addition of water.

Experimental sequence showing the order in which silicate minerals crystallise from cooling magma, from olivine and calcium plagioclase to quartz and potassium feldspar, explaining igneous rock compositions.

Set of processes such as fractional crystallisation, assimilation and magma mixing that change a magma's composition during cooling, producing diverse rocks from a single parental melt.

Assemblage of minerals that forms in a rock under a defined range of pressure and temperature, used to reconstruct the conditions a metamorphic rock experienced.

Confining pressure exerted equally in all directions by the weight of overlying rock, increasing roughly 1 kbar per 3-4 km depth and controlling metamorphic mineral stability.

Fracture in rock along which displacement has occurred; classified as normal, reverse or strike-slip according to the sense of relative movement and the prevailing stress field.

Permanent bending of layered rock under compressional stress, described by its hinge, limbs and axial plane; anticlines arch upward and synclines sag downward.

Episode of mountain building caused by convergence of plates, producing folding, thrusting, metamorphism and crustal thickening, as in the Alpine chain of the western Mediterranean.

Surface separating rock units of different ages that represents a gap in the record, formed by erosion or non-deposition and used to decipher geological history.

Rule stating that in an undisturbed sequence of sedimentary layers, each bed is younger than the one below and older than the one above it.

Method of ordering geological events and rocks without assigning numerical ages, relying on superposition, cross-cutting relationships, inclusions and fossil content.

Fossil of a species with wide geographic distribution and short stratigraphic range, used to correlate rock layers and identify geological periods.

Branch of stratigraphy that subdivides and correlates rock successions using their fossil content, especially the first and last appearances of index species.

Radiometric technique that calculates absolute ages from the ratio of a radioactive parent isotope to its decay product, using known half-lives, as in potassium-argon or uranium-lead methods.

Time required for half the atoms of a radioactive isotope in a sample to decay, the constant that allows radiometric ages to be calculated from measured isotope ratios.

Periodic variations in Earth's orbit and axial tilt (eccentricity, obliquity, precession) that alter the distribution of solar energy and pace glacial-interglacial cycles.

Mineral built around the silicon-oxygen tetrahedron, forming the largest mineral class; subdivided into nesosilicates, inosilicates, phyllosilicates and tectosilicates according to how tetrahedra link.

Relative scale from 1 (talc) to 10 (diamond) ranking minerals by their resistance to scratching, used as a simple field test for identification.

Tendency of a mineral to break along flat planes determined by weak bonds in its crystal lattice, such as the perfect basal cleavage of micas.

Rock made of fragments of pre-existing rocks and minerals cemented together, classified by grain size as conglomerate, sandstone, siltstone or mudstone.

Set of low-temperature processes (compaction, cementation, recrystallisation) that convert loose sediment into solid sedimentary rock after deposition and before metamorphism.

Body of sediment or rock with characteristics reflecting a particular depositional environment, allowing ancient settings such as reefs, deltas or deep basins to be reconstructed.

Balance between incoming shortwave solar radiation absorbed by the Earth and outgoing longwave infrared radiation emitted to space; imbalance alters global temperature.

Warming of the lower atmosphere because gases such as carbon dioxide, methane and water vapour absorb outgoing infrared radiation and re-emit it towards the surface.

Change imposed on the Earth's energy balance by an external factor such as solar variation, volcanic aerosols or greenhouse gas emissions, measured in watts per square metre.

Process triggered by an initial temperature change that amplifies it (positive feedback, such as ice-albedo loss or water vapour increase) or dampens it (negative feedback).

Permeable rock or sediment body able to store and transmit groundwater in usable quantities; may be unconfined with a free water table or confined between impermeable layers.

Upper surface of the saturated zone in an unconfined aquifer, whose depth and shape vary with recharge, discharge and pumping.

Extraction of groundwater faster than natural recharge, causing falling water tables, land subsidence, drying of springs and deterioration of water quality.

Movement of seawater into coastal freshwater aquifers when pumping lowers the water table below the level needed to keep the denser saline wedge offshore.

Vertical sequence of horizons (O, A, E, B, C, R) developed in a soil, reflecting the processes of organic accumulation, leaching, illuviation and weathering.

Detachment and removal of topsoil by water or wind, accelerated by vegetation loss, fire, steep slopes and intensive land use, reducing fertility and increasing sediment loads.

Land degradation in dry or sub-humid areas caused by climatic variation and human activity, leading to loss of vegetation cover, soil productivity and biodiversity.

Landscape formed by dissolution of soluble rocks such as limestone and gypsum, characterised by sinkholes, caves, poljes and disappearing streams; widespread in the Balearic Islands.

Ridge of wind-blown sand behind a beach, stabilised by vegetation; a dynamic buffer against storms that is vulnerable to trampling, construction and sea-level rise.

Retreat of the shoreline caused by wave action, currents and sediment deficit, often worsened by hard defences, dune loss and rising sea level.

Point inside the Earth where an earthquake rupture begins and seismic energy is released; its projection on the surface is the epicentre.

Probability that ground shaking of a given intensity will affect a place within a time period, estimated from seismicity, fault mapping and site conditions.

Formal procedure that predicts the environmental effects of a proposed project, evaluates alternatives and defines mitigation measures before authorisation is granted.

Legally designated territory managed to conserve biodiversity, habitats or landscapes while regulating human uses such as building, hunting or visitor pressure.

Principle of meeting present needs without compromising the ability of future generations to meet theirs, applied to resource use, land planning and waste management.