A

aa

A fluid lava flow with a rugged appearance.

alcrete

A type of duricrust composed of aluminium minerals.

Amphibole

Class of rocks having aluuminosilicate minerals e.g. granite

Andesite

A fine and dark coloured igneous rock containing pagioclase feldspars and hornblende.

Arkose

A coarse grained sedimentary rock (sandstone) containing quartz and feldspars.

Anticline fold

An arch shaped symmetrical fold. See Folds

Ash

Small debris particles of less than 4mm extruded from a volcano. See Volcanoes

asthenosphere

A zone in the uppermost mantle consisting of weak volcanic rocks. This layer keeps the plates floating. See Plate Tectonics

Avalanche

A type of mass movement containing ice and debris. See Mass Movements

B

Basal Surface

An unweathered rock lying beneath the earth's surface. Also known as bedrock. See Deep weathering

Basalt

A mafic (dark coloured) igneous rock containing plagioclase feldspars, pyroxenes and or olivine. Easily weathered.

Basin

A depressed land area either from folding (Folding) or other land depressors e.g ice.

Batholith

A large pluton (intrusive) that often show up as a mountain when it is exposed to the surface by erosion or uplift. See Plutons, Intrusive Features

Blind valley

A valley common in karst regions closed at the end by a hard strata or slope which diverts any channel down the limestone. See Karst landscapes

body waves

Earthquake waves that travel below the surface. See earthquakes.

Bornhardt

A dome shaped inselberg rising abruptly from a plain. SeeGranitic Inselbergs

Breccia

A sedimentary rock with large, angular fragments of quartz.

Bysmalith

A pluton that has a fault across it. See Intrusive Volcanic Features: Plutons

Calcite

A white mineral composed of calcium carbonate common in limestone rocks. See Limestone Properties

Calcrete

A duricrust of dried up calcite. SeeDuricrust

Caldera

A large depression formed when super eruptions blows and collapse the flanks of a volcano. SeeVolcanoes

canyon

See gorge.

carbonation

A type of chemical weathering were acidulated water containing carbon dioxide reacts with limestone rocks containing caclite (calcium carbonate) turning it into calcium bicarbonate.

castle kopje

An inselberg with balanced rocks on top of each other forming a castle appearance. See Granitic Inselbergs

chalk

A white and soft sedimentary rock composed of calcite (calcium carbonate) and formed from dead organic matter such as sea creatures and plants.

chemical weathering

Weathering by means of reactions between rock and different elements such as water and acids. See Chemical Weathering

chelation

The weathering of rocks by acids released from decayed organic matter. See Chemical Weathering

cinder cone

A small volcano which mainly extrudes fragmented lava (scoria)

cliff

See scarp

clint

The troughs found on a limestone pavement formed when carbonated water attacks and deepens vertical joints.

cockpit

Star shaped depressions separating conical hills in a limestone terrain formed when water attacks lines of weakness.

Cohesion

The ability of particles to strongly stick together resisting movement.

Colluvium

Debris washed down at the foot of a slope

conical karst

In a karst topography water attacks lines of weakness leaving behind conical and circular hills.

composite cone

A cone shaped and catastrophic volcano which mainly generates ash and pyroclastic materials. See Volcanoes

concordant

Small volcanic intrusions (plutons) running across the bedding planes of large volcanic plutons. See Plutonic Forces

convergent boundary

A catastrophic plate boundary between oceanic and continental, oceanic and oceanic or continental and continental plates that collides generating volcanic activities, mountains and earthquakes. See Plate Boundaries

continent

The land area of a plate consisting of sial. See Plate Tectonics

continental crust

The outermpst continental section consisting of sial which is more thicker than the oceanic crust. See Plate tectonics

continental shelf

The extended part of a continent into the ocean.

corestone

Small to medium sized circular rocks constituting saprolite of deep weathered profile. See Deep weathering

concave slope

The lower unit of a slope. See Slope Profiles

conglomerate

A sedimentary rock with interbedded pebbles and cobbles.

convex slope

The upper unit of a slope. See Slope Profiles

crater

A circular blowout left on top of a volcano when an eruption occurs. See Volcanoes

crust

The outermost layer of the earth.

cumulo-dome

A dome shaped volcano that extrudes viscous, less runny lava that quickly solidifies.

D

Debris

All loose weathered or eroded material found on the surface.

Deep weathering

The weathering of underground rocks by water and humic acids that percolate through the soil.

dip

The angle made by a stratum with the horizontal surface.

divergence boundary

A plate boundary where plates split (move apart) creating an opening that oozes magma to the top.

dome

A more folded anticline.

duricrust

A hard layer(crust) found on top of hills or plateaus made from mineral precipitation.

dike/dyke

An often small discordant pluton that runs across existing rocks

diorite

A coarse grained igneous rock consisting of quartz, feldspar and hornblende.

dolerite

A dark, medium coarse grained igneous rock that forms many sills and dykes.

dry valley

A dried up valley with traces of prior water flow that percolated down a limestone. See karst landscape

dwala

A low lying basal surface exhumed from underground by the stripping of regolith. See Granitic inselberg

E

earthquake

A sudden movement in the earth's crust caused and triggered by plate movements and volcanoes. See

endogenic

Denoting all processses occurring internally the earth's surface.

epicenter

The area on the ground, above the focus, where an earthquakes first hits. See earthquakes.

etchplanation

The weathering of underground rocks producing deep regolith which is then stripped away revealing weathered rocks as inselbergs. See Inselberg Formation

exfoliation

A type of physical weathering were a rock's outer layer peels off caused by repeated expansion and contraction by insolation. See Physical Weathering

exhumation

The stripping away of regolith revealing underground basal surfaces or piling boulders as inselbergs.

Exogenic

Denoting all processes occurring on or out of the earth's surface.

Felsic

Denoting dark coloured minerals in igneous rocks

flowstone

Calcite that flows along cave walls and dry out.

Free face

See Cliff

focus

The origin of an earthquake deep in the lithosphere.

Foot slope

See Concave Slope

freeze-thaw action/ frost shattering

A type of physical weathering were ice exerts tremendous pressure against a rock causing it to disintegrate. See Physical Weathering

fumarole

Emitted hot gases through cracks around a volcano.

geomorphology

The study of earth's landforms, their form, shape and structure.

Gabbro

A hard, dark and coarse grained igneous rock.

gorge

A narrow steep sided valley.

Gully

On slopes, these are widened and deepened rivulets. See Processes on Slopes

Geyser

An volcanic landform where steam is ejected by the heating of water by underground hot rocks.

graben

A downthrow block of land between two upthrowns called horsts.

grike

An acid eaten trough found along a limestone pavement separated by ridges known as clints. See Karst Landscape

gypsum

A soft whitish sedimentary rock consisting of hydrated calcium sulphate.

H

half graben

A fault in which a block of land (downthrow) slides down over one curved fault line. See Faults

Hogback

A steep fold of about 45^o.

Hortonian Overland flow

The concentrated or unconcentrated flow of water in rills or as sheetwash respectively down a slope. See Hortonian Overland flow

Hotspot

An intensely hot area where magma is constantly supplied. Mainly found in plate interiors. See Volcanic Hotspots

Hot spring

A spring of natural hot water heated by underground rocks.

Humification

See Chelation

Hydration

A type of chemical weathering were repeated absorption of water and swelling disintegrates a rock. See Chemical Weathering

Hydrolysis

A type of chemical weathering were rock minerals reacts with water causing them to disintegrate into fine soil. See Chemical Weathering

hypabyssal

Small plutons (intrusive features) that solidify just below the surface.

I

igneous rocks

Rocks formed from the solidification of magma at depth or lava on the surface.

Inselberg

A small to medium isolated hill rising abruptly from a plain. See Inselberg Formation

interfluve

An upland area between two adjacent watercourses.

isoclinal fold

A fold with limbs that run parallel in the same direction. See folds

L

laccolith

Are dome shaped intrusive features made from viscous lava that quickly solidifies at depth. See intrusive volcanic landforms

Lahar

A type of mudflow consisting of volcanic debris mixed with water. See Volcanoes

landslide

The sliding of blocks (en mass) of land along a slip plane. See mass movements

Lapilli

Small pyroclastic particles between 4 and 30 mm. See Volcanoes.

lapolith

A saucer shaped pluton often as large as a batholith. See Intrusive Volcanic features

laterite

A red brownish soil reach in insoluble iron minerals.

lava

The molten rock found on the earth's surface. See Volcanoes

limestone

A soft sedimentary rock containing the mineral calcite (calcium carbonate). See Limestone

limestone pavement

An small or large outcrop of limestone usually demoted with grikes and clints. See karst landscape

lithification

The conversion to rock.

lithosphere

Rigid part of the earth consisting the uppermost mantle and the crust. Also known as plate.

lithology

Denoting to rocks, their structure and form.

M

maar

A shallow and broad volcano (crater) that erupts on the surface with groundwater. See volcanoes.

magma

The molten rock below the earth's surface.

mantle

The region between the outer core and the crust consisting of dense silicate rock.

mantle plume

A rising column of magma forming a massive dome of magma just below the surface or a hotspot on the surface. See Hotspots

metamorphic rocks

Rocks formed by intense heat and pressure on other rocks (igneous, sedimentary or metamorphic).

mica

A shiny silicate mineral commonly found in granite

mineral precipitation

The process where water evaporates from minerals or the process where minerals are deposited from a solution.

monandock

An isolated hill rising abruptly from a plain. Also known as inselberg

monocline

An asymmetrical fold with raised limb. See folds

mudflow

A fast mass movement carrying water laden coarse sediments. See Mass Movements

mudstone

A dark sedimentary rock with a consolidated mixture of clay and silt

N

nubbin

A small mound of exhumed granitic boulders. See Granitic Inselbergs

Nuée ardent

A fiery cloud of ash and pyroclastic debris. See volcanoes

O

orogenesis

The building up of mountains by tectonic processes

overland flow

The unconcentrated or concentrated movement of water on a slope as sheetwash or in rills respectively.

Oxidation

A type of chemical weathering where water reacts with iron rich rocks causing a reddish colouration(rust). See chemical weathering

P

Pahohoe

A viscous lava with a smooth and wrinkled pattern

parallel retreat

According to C.King, a process where scarps retreat back inland, maintaining steepness, leaving a pediplain behind. See Slope Evolution

passive margin

A boundary found within continents away from major tectonically active margins.

Plant Root Action

A type of physical weathering where a rock disintegrates due to plant roots between cracks exerting pressure against the rock. See Physical Weathering

Pediplain

According to C.King, a flat and extensive land area left when scarps retreat. See Inselberg Formation Theories

Pediment

A gently sloping extension of a plateau or hill (inselberg). See Inselbergs

permeable

Allowing water to pass through

pervious

See permeable.

Peneplain

According to W.M Davis, this represents the last stage of erosion characterised by a levelled land surface. See Slope Evolutional Theories

polje

A near steep sided valley with a flat floor found in a karst landscape. See Karst Landscape

ponor

See sinkhole

porphyry

A rock, usually igneous, with coarse grains interbedded in a fine groundmass (small grains)

pressure release

A physical weathering type where underground rocks are subjected to differential pressures and temperatures on the surface causing them to develop cracks running parallel to the surface.

Q

quartz

A crystal shiny mineral mostly native to igneous rocks such as granite.

R

rainsplash

The process whereby raindrops dislodge and erode soil grains on a surface. See Slope processes

rectilinear slope

The middle transportation unit of a slope where the gradient is constant. See Slope Profiles

recumbent fold

Extremely folded rocks forming a "Z like" pattern. See Folds

regolith

All the unconsolidated debris covering the bedrock below the earth's surface. See Deep weathering

reverse fault

A fault where the downthrow slides up the upthrow. See faults

rills

Tiny streams created by running water along slopes

rivulet

See rill

rift valley

A downthrow (valley/graben) which slides down between two fault lines. See Rift Valley

rockfall

A mass movement where weathering, water or earth movements collapse rock boulders along a scarp. See mass movements

runoff

Water running down a slope as overland flow or throughflow. Runoff encompasses all types of water flow. See Slope Processes

S

sandstone

A hard sedimentary rock cemented with fragments of quartz and sand.

salt crystallisation

A type of physical weathering where salts within rock cracks expand causing the eventual disintegration of the rock. See physical weathering.

saprock

The first deep weathered layer consisting of boulders. See deep weathering.

saprolite

A deep weathered layer comprising of weathered corestones. See Deep weathering

scarp

A steep and resistant rock face uncovered by debris found on the edges of plateaus, valleys and or inselbergs. Also called scarp.

schist

A coarse grained metamorphic rock.

scree

Pile of weathered or eroded material covering a slope.

sedimentary rock

A rock type formed from grains of other rocks or remains of dead plants and animals.

shale

A fine clay sedimentary rock.

sheetwash

A type of overland flow where water moves unconcentrated collecting soil in the path. See Processes on slopes

sial

Denoting chemical composition of the continental crust

sill

A discordant pluton (intrusive feature) running horizontally to existing sedimentary rocks. See plutons.

slicrete

A duricrust of silica.

sima

Denoting chemical composition of the oceanic crust.

slip fault

See transform fault

slope

Any inclined surface.

slope decline

(W.M Davis) The process where the landscape lowers into a flat undulating plain with time. see Slope evolution

slope replacement

(W. Penck) The engulfing of the entire slope by a growing basal surface (debris) with time. See Slope evolution

slope retreat

(C. King) The denudation of scarps causing them to wear backwards. see Slope evolution

slump

A rotational slide where blocks of land sits on top of another. see Mass movement

soil creep

The slow movement of soil grains down a slope. See Mass movements

solifluction

A periglacial mass movement where debris moves atop the impermeable frozen bedrock/surface. See mass movements

speleotherms

Denoting all deposits of calcite in a cave

surface waves

Earthquake waves that travel along the surface.

sub-surface flow

See throughflow

super-volcano

See composite cone

sycline

Saucer shaped symmetrical fold.

T

tafoni

A hollowed out depression on a rock surface eaten out by weathering.

talus

Weathered or eroded material (usually small stones) on the foot of scarp.

terracing

The process of building steps along a slope to minimise mass movements.

tors

Small to large boulders piling on top of another exhumed from underground. See Granitic inslebergs

tower karst

Tall towers of limestone of 200m or more created when acidulated water widens and deepens joints on a limestone terrain. See Karst Landforms

transform fault

A plate boundary where plates slide past each other or together.

translational slide

See landslide

travertine

A limestone with an inorganic origin. See limestone properties

U

uvala

An enormous depression found in a karst landscape formed from the coalescence of several sinkholes or tectonic depressions.

V

vadose

Denoting underground water lying above the water table.

valley

A depression between hills, plateaus or mountains usually with a river in between.

viscous lava

A thick and less runny lava that congeal and solidifies quickly.

W

weathered mantle

See regolith

weathering

The breakdown of rocks by physical or chemical means.

weathering front

The boundary separating the weathered regolith from the bedrock. See Deep weathering

whaleback

See Dwala