in which Hooke's Law holds.Ypresian - In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between ~56 Ma and ~49 Ma (million years ago).Z[edit]Zeolite - microporous, aluminosilicate minerals commonly used as adsorbent.Zircon - a zirconium silicate mineral belonging to the group of nesosilicates. Its corresponding chemical formula is ZrSiO4.Glossary of Basic Geological TermsEnglish termCzech termExplanationablationablaceThe process of decreasing of ice volume of a glacier. Synonym wastage.abrasionabrazeThe grinding away of a rock by friction and impact during transportation.absolute ageabsolutni stariAge given in years or some other unit of time (mostly in million of years).abyssal fanabysalni dejekcni kuzelGreat fan-shaped deposit of sediment on the deep-sea floor at the base of many submarine canyons.abyssal plainabysalni rovinaVery flat sediment-covered region of the deep-sea floor, usually at the base of the continental rise.accessory mineralsakcesoricke mineralyRock-forming minerals which occur in a rock in a very small amount (several percents of mineral content) and which have no effect to classification of a rock.acid rockskysele vyvrele horninyIgneous rocks with high amount of silica. They are macroscopically recognizable by high percentage of quartz, K-feldspars and/or acidic plagioclases.advancing glacierpostupujici ledovec (rostouci)Glacier with a positive budget, so that accumulation results in the lower edges being pushed outward and downward.aftershockSmall earthquake that follows a main shock.albitealbitKind of plagioclase (acidic) within the feldspar group with formula NaAlSi3O8. Its colour is light grey to grey. Other properties see feldspars.aleuritesaleurityClastic sediments or sedimentary rocks with size of particles between 0,002-0,063 mm.allothigenous mineralsMinerals, which were transported from other place into a newly formed sediment. These minerals are highly resistent to weathering processes.allotriomorphic mineralsalotriomorfne omezene mineralyMinerals of igneous rocks which crystallize as latest in a process of magma crystallization. It results in a shape of these minerals, which are forced to crystallize in a space created by formerly crystallized sorrounding minerals.alluvial depositsaluvialni sedimentyGeneral term for clastic sedimentary rocks with no cohesion, which have been transported and deposited by a stream.alluvial fanaluvialni kuzel (dejekcni)Large fan-shaped pile of sediment that usually forms where stream s velocity decreases as it emerges from a narrow canyon onto a flat plain at the foot of a mountain range.alpine glaciationalpinske zaledneniGlaciation of a mountainous area.amorphous substanceamorfni latkaSubstance where atoms are not ordered in crystal lattice.amphiboleamfibolFerromagnesian mafic mineral which belongs to silicates. Properties: black in colour, cleavaged, cleavage planes are stepped rather than smooth, splintery appearance, columnar, hardness is from 5 to 6, vitreous or silk luster.amphiboliteamfibolitMostly black, amphibole (hornblende), plagioclase schist with characteristic plane parallel structure (compare with hornoblendite).amygdaloidal structuremandlovcovita texturaType of structure of igneous rocks, which is typical for its "almond shaped" pores secondary filled with material. This structure is formed after porous structure.andesiteandezitFine-grained igneous rock of intermediate composition. Up to half of the rock is plagioclase feldspar with the rest being ferromagnesian minerals. It is often porphyritic.angularostrohrannySharp-edged; lacking rounded edges or corners.anhydriteanhydritAnhydrite is a relatively common sedimentary mineral that forms massive rock layers. Anhydrite does not form directly, but is the result of the dewatering of the rock forming mineral Gypsum (CaSO4-2H2O). Color is ordinarily white, gray or colorless but also