Geological Sites of NSW banner

Cartoscope maps banner

Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
A

Aeolian: A combination of wind-blown sands and sedimentation

Alunite: Alunite varies in colour from white to yellow gray. The mineral is a hydrated aluminium potassium sulphate and occurs as veins and replacement masses in trachyte, rhyolite, and similar potassium rich volcanic rocks. It is formed by the action of sulphuric acid bearing solutions on these rocks during the oxidation and leaching of metal sulphide deposits

Aplite: Aplite is formed from the final, residual magma left over when the bulk of granite has crystallised

Artesian water: Artesian water is underground water confined and pressurised within a porous and permeable geological formation. Formations that store and transmit water are referred to as aquifers


B

Banatite: A rock of intermediate composition between quartz diorite and quartz monzonite

Basalt: A dark coloured, commonly extrusive, dense igneous rock of a lava flow or minor intrusion (e.g. dyke)

Basement: Underlying rocks

Batholith: A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earth's crust

Bioturbation: All encompasing displacement and mixing of sediment particles

Boxwork weathering: Where jointing in the rock has been filled with mineral solutions and over time have accumulated into harder rock bands that are more weather resistant than the base rock; Curious smooth humps of pillow shaped siltstone

Buddle: An inclined trough in which crushed ore is washed with running water to flush away impurities


C

Caldera: A caldera is a bowl shaped depression caused by the collapse or erosion of a volcanic cone

Cirque lake: A circular bowl shaped lake created by glacial action scraping a profile in the native rock

Coffee rock: Using a solution of sodium or potassium cyanide to release gold from ore

Conglomerate: Conglomerates are sedimentary rocks consisting of rounded fragments cemented together

Corundum (ruby or sapphire): A crystalline form of aluminium oxide (Al2O3)

Cuesta: Asymmetrical ridge

Cyanidation: Hardened sands and sediments


D

Diatomite: (Diatomaceous Earth) is composed essentially of the siliceous cases or "frustules" of minute plants known as diatoms which inhabit fresh and salt water. It is a very light, porous substance, somewhat friable.

Diatreme: A breccia-filled volcanic pipe that is formed by a gaseous explosion

Dolines: Funnel or saucer-shaped sinkholes in limestone

Ductile fashion: A solid material's ability to deform under tensile stress

Dyke: A dyke is an intrusion of magma into a fissure, shouldering aside other pre- existing bodies of rock; a dyke is always younger than the rocks that contain it.


E

Earth's dipole field: Approximation of the rather complex true Earth's magnetic field

Endorheic basin: A closed drainage basin that retains water and allows no outflow to other bodies of water such as rivers or oceans

Essexite: A type of igneous rock


F

Facies: A facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment

Foliation: Parallel alignment of the textural and structural features of a rock


G

Gibber: Describes a small rock or pebble which forms a pavement with similar rocks on the surface of desert landscapes

Glaciers: Glaciers are an extended mass of ice formed from snow falling and accumulating over years and moving very slowly, either descending from high mountains as in valley glaciers, or moving outwards from centres of accumulation as in continental glaciers

Gneisses: Rock formed by high-grade regional metamorphic processes

Gossan: Weathered sulphide outcrops

Gypsum: Used in the manufacture of gyprock wall board


H

Hummocky crossstratification: A type of sedimentary structure in which the original depositional layering is tilted


I

Inselberg: Isolated rock hill

Intrusive: Intrusive means below ground


K

Karren: Surface solutional formations

Karst: Karst is the type of land formed over limestone caves, sinkholes, underground drainage and other soluble rocks

Kink zone: A zone subjected to great pressure during the movement of tectonic plates

Krasnozems: Highly weathered red-clayey soils


L

Laterites: Soil types rich in iron and aluminium, formed in hot and wet tropical areas

Latite lava units: Alkali rich igneous rocks of basaltic appearance

Limonite: A secondary mineral which would have filled the microscopic voids in tree tissues as they decayed replacing wood with mineral.

Lineaments: Long linear surface exposure that could indicate a structural feature

Lunette: A lunette is a single, massive dune ridge formed from clay and sand blown up from a lake

Lycopod: A fossil plant like a modern tree fern


M

Ma: Stands for megaannum, which is a unit of time equal to one million years

Maars: Shallow volcanoes created from groundwater coming in contact with lava/magma

Mafic Lavas: A silicate mineral or rock that is rich in magnesium and iron)

Metamorphic Rock: Any rock transformed from pre-existing rock by mineralogical, chemical or structural changes

Moraines: Ridges of ground up rock and other debris dumped along the sides or the tongue of a melting glacier


O

Onion skin weathering: Rinds of weathered granite wrapped about fresh granite may resemble the structure of an onion

Ordovician magmatic arc: A curved linear belt of volcanoes above a subduction zone, where tectonic plates collide


P

Pagodas: Beehive, dome, castellated and elaborate platform shaped features

Palaeosol: A former soil preserved by burial underneath sediments and lithified into rock

Pillow lava: This rock shape is most often the result of undersea volcano eruptions. When lava from these eruptions was cooled quickly by the ocean it formed pillow shapes: as the outside hardened and then filled and burst, the fresh molten lava within then spilled over to form another pillow.

Phreatic development: Cave formed primarily below the water table

Planeze: one of a series of triangular facets facing outward from a conical volcanic peak and separated by radiating streams which run down the flanks of the cone

Plate tectonics: Plate tectonics is the slow, lateral movement of segments of the earth's hard outermost shell. It is the movement of plates that splits and moves continents, that forms mountains, that triggers earthquakes and causes volcanoes

Porphyritic: A rock that has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group.

Protolith: The original rock from which a given metamorphic rock is formed. For example, the protolith of marble is limestone.

Pyrite: Fool's gold


R

Rillenkarren: Weathered fluting

Ring dyke: A ring dyke typically forms when an underground pool of hot molten rock drains away. The pool's roof then collapses, forming cracks. Molten volcanic rock is then squeezed through the cracks to form dykes, which are roughly circular. As the softer rock eroded the hard volcanic dyke rock on the sides remained.


S

Scalding: The process whereby large areas of topsoil are exposed due to the removal of vegetation

SedEx deposits: Sedimentary exhalative deposits

Speleogens: Features formed by erosion and weathering

Stratiform ore: Ore minerals are distributed in a manner that resembles particles in a sedimentary rock

Subduction zone: is an area where tectonic plates collide together, with one plate overlapping and overriding the other; the subducted plate - the plate underneath - can sink to great depths in the Earth's mantle


T

Terrane: Crustal material formed on, or broken off from, one tectonic plate and sutured to crust lying on another plate

Tors: Tors are rounded, block-like outcrops of granite

Trilobites: Extinct arthropods

Tropical weathering (laterization): A prolonged process of chemical weathering which produces a wide variety in the thickness, grade, chemistry and ore mineralogy of the resulting soils

Tufa: Deposits of calcite around springs

Tuff: Consolidated volcanic ash


U

unconformity: A contact separating two rock masses of different ages

Unloading: Unloading results in the expansion of rocks nearing the earth's surface, which results in horizontal cracking


V

Varved siltstones: Thinly banded siltstones, showing a cyclical repetition of thin and thick layers

Volcano: A volcano is a vent in the surface of the earth through which magma and associated gases and ash erupt. Also the form or structure, usually conical, that is created by the ejected material


W

Weathering: Weathering is the chemical alteration and mechanical breakdown of rock and sediment when exposed to air , moisture and organic matter


X

Xanthorrohea: Grass trees


© Copyright Cartoscope and Others