Physical Geography Glossary

Evaporation – When high temperatures turn liquid drops to gaseous molecules.

Condensation – When low temperatures turn gaseous molecules to liquid drops.

Precipitation – When liquid drops fall to the surface that were formed in a saturated atmosphere.

InfiltrationAbsorption and downward movement of water from the surface to the soil.

Percolation – Vertical movement of water down the bedrock.

Ground Flow – Underground flow of water in the bedrock due to gravity.

Through Flow – Horizontal flow of water underground in the soil.

Overland Flow – Downwards flow of water on the surface to the sea.

—Source – The origin of the river.

—Mouth – The end of the river where it meets the body of water.

—Confluence – The junction where 2 rivers meet.

—Tributary – A small channel that flows into the main channel.

—Distributary – A small channel that flows out of the main channel.

—Watershed – The catchment area of water, marking out the drainage basin.

—Discharge – The volume of water passing trough a river at a given time.

—Erosion – The removal of weathered sediment from the river by its forces.

Hydraulic Action – The removal of loose material in the river bed or banks due to the frictional drag of water on the channel bed.

Abrasion – The scouring and scrapping action of the load against the bed and banks, breaking them down.

Attrition - The reduction in size of the load as they strike one another, hence becoming smaller and smoother.

Corrosion – When the minerals in the rock are dissolved by weak acids in the river and are broken down.

—Lateral Erosion – Erosion of the river banks.

—Vertical Erosion – Erosion of the river bed.

—Entrainment Velocity – The velocity needed to pick up the river’s load.

—Kinetic Energy – Energy in the river due to movement.

—Gravitational Potential Energy – Energy that the river has depending on its position. It gets transformed into kinetic energy as the river travels downwards.

—Transport – The movement of the load through the river.

—Traction – When the load rolls along the river bed as the water pushes it.

—Saltation – When the load bounces along the river bed as the flowing water pushes it.

Suspension – When particles are carried along the water through the river’s turbulence.

Solution – When small minerals dissolve into the water are transported by it.

—Capacity – The amount of material a river can carry.

—Competence – The diameter of the largest possible particle a river can carry for a given velocity.

—Deposition – The laying down of sediment transported by the river.

—Rejuvenation – An increase in the energy of the river caused by a fall in the base level or an uplift in land.

—Magnitude Frequency Analysis – A measure to show the size of a flood and how often it will happen.

—Flooding – The point at which the river’s capacity is exceeded and the discharge of the river overflows onto the land.

—Hard Engineering – The construction of flood defences by using physical materials to manage the river.

—Soft Engineering – The use of the natural environment to manage the river’s discharge.

—Polar Environment – Regions that are covered by ice sheets and surround the poles. E.g. Antarctica

—Periglacial Environment/Tundra – An area adjacent to a polar environment. It is on the edge of a glacier. E.g. Northern Russia.

—Alpine Environment – An area that is very mountainous located in a cold environment. E.g. Tibet.

—Ablation – The melting of the ice.

Compressing Flow – A reduction in the gradient of the valley, causing the glacier to slow down.

Extending Flow – When the gradient of the valley increases, hence making the glacier speed up.

—Basal Flow – When increased pressure on the base of the glacier causes the ice to melt into meltwater.

—Internal Deformation – When the ice crystals orientate themselves in the direction of movement.—They slide past each other down the valley. This is how crevasses develop.

Rotational Flow – —When the ice pivots around a point in the valley.

Creep – —When stress builds up in the glacier, it enables it to move and behave like a plastic.

—Abrasion – When the material inside the glacier and the ice itself scours and scrapes the valley bed and sides, causing rock to fall off.

—Plucking – When the glacier freezes onto the rock. When the glacier moves forward, it pulls the rock and forces it to be ripped off.

—Frost Shattering – The breaking of rock as water moves into its cracks and expands as it freezes.

Nivation – —The hollowing of the rock due to the presence of ice.

—Corrie – An armchair shaped rock hollow in the valley. It has a steep wall, tarn and corrie lip.

—Arête – Occurs when two corries on opposite sides of a valley/ridge begin to erode into eachother.

—Pyramidal Peak – When 3 corries erode into each other around a single point.

Truncated Spurs – Formations which form when the glacier erodes through inter-locking spurs, formed originally by meanders.

Hanging Valley -—This is a smaller sized valley which overlooks the main channel.

Ribbon Lake – —A landform which occurs when the glacier erodes the valley.

Misfit River – A river which flows in a valley which it did not erode.

—Lodgement Till – Till deposited from am moving glacier.

—Ablation Till – Till deposited from a melting glacier.

—Moraine – Glacial till which has been sorted.

—Lateral Moraine – Moraine located on the sides of the glacier.

—Ground Moraine – Moraine located at the base of the glacier.

—Medial Moraine – A line of moraine that is located in the middle of the glacier.

—Terminal Moraine – Deposited moraine when the glacier has reached its furthest point and stopped.

—Recessional Moraine – Lines of moraine deposited and sorted as the glacier retreats.

Drumlin – A landform of shaped moraine. —It forms when a glacier moves over the moraine in the valley. It is not exactly know how they form.

—Meltwater Channel – A stream/river that flows down the valley which originates from the glacier’s meltwater.

—Subglacial Channels – Meltwater channels that flow under the glacier at the base. They form due to increased pressure.

—Ice Marginal Channel – Meltwater channels that flow along the sides of the glacier. They are located between the glacier and valley. They form due to increased pressure

—Proglacial Channels – Meltwater channels that flow in front of the glacier. They from due to rising temperatures.

—Outwash Plain – The flat expanse of sediment deposited in front of a glacier.

—Esker – A sinuous trail of deposited material from a subglacial channel. It shows the channel’s course.

—Kame – A deposited mound of sediment left in the path of a retreating glacier.

—Varve – The varying layers of sediment which gets deposited due to seasonal rates of deposition.

—Kettle Hole – A small lake formed from melted dead ice in the valley.

—PermafrostPermanently frozen ground in a glacial environment. It must be frozen for 2 years.

—Continuous Permafrost – Permafrost which covers all of the ground. It reaches very deep levels. There is very little melting in the active layer.

—Discontinuous Permafrost – Permafrost which does not cover all of the ground and is separated out. —The active layer melts easily.

—Sporadic Permafrost – Permafrost in very isolated spots with little surface area and little depth. —The active layer melts easily.

Solifluction – When —the active layer thaws in warmer temperatures, the ice thaws and turns to water, which lubricates the surface.

Ice Wedges – Gaps in the permafrost made of ice.