Physical Geography Ez Flashcards
The Earth’s Layers
Crust
● Mantle
● Outer core
● Inner core
Plates
● 7 major plates
● Destructive plates (two colliding plates)
● Constructive plates (two separating plates)
Convectional currents
The very hot core heats the magma
● Convectional currents are set up in the mantle
● Molten magma moves upwards from the core towards the crust
● At the crust, the magma cools and sinks back down towards the core so the cycle can
start over again
● There is friction between the convectional currents and the plates
● The friction causes the plates to move slowly on top of the mantle
● As a result, the plates may collide or pull apart from each other
Mid-ocean ridge
Underwater mountain range
● Formed where two plates separate
● As the plates move apart, molten magma rises from the mantle and fills the gap between
the plates
● When the magma meets the cold seawater, it cools and solidifies to form a new ocean
floor
● As the eruptions of magma continue in an endless cycle, the ocean floor is built up to
form a long ridge of mountains
Volcanoes
Magma from the magma reservoir reaches the surface through a v ent which may erupt
violently, blasting materials into the sky through the crater
● When magma reaches the surface, it’s known as lava
● Lava pours out of the crater and flows down the side of the cone, cooling and hardening
● Other materials may also come out during the eruption
● Layers of these materials build up to form a cone shaped mountain
Types of volcanoes
● Active volcanoes still erupt on a regular basis e.g Mount Vesuvius
● Dormant volcanoes erupted in the past but may not erupt again e.g Mount Cotopaxi
● Extinct volcanoes have not erupted in historic times e.g Mount Slemish
Advantages of volcanoes
Fertile soil
● Precious stones and minerals can be originated in volcanoes
● Building materials from rocks formed as a result of volcanic eruption (igneous rocks)
● Hot springs and geysers can be used to generate electricity
● Volcanoes attract tourists
Disadvantages of volcanoes
Loss of life
● Damage to property
● Destroys wildlife and the environment
Pacific Ring of Fire
Active volcanoes that surround the Pacific Ocean
Fold mountains
They are found along plate boundaries
● When two plates collide, the rocks tend to buckle and crumple upwards into a series of
folds
● Large amounts of compression occurs
● Armorican fold mountains are smaller in size because they are older and have been
severely worn done
● Alpine fold mountains are larger in size because they are younger and have not been as
severely worn down
Earthquakes
● An earthquake is a sudden movement or trembling or the Earth’s crust
● This movement takes the form of a series of shocks or tremors
● Earthquakes occur at boundaries where plates collide
● As the plates push into one another pressure builds up until one of the plates slips
● The plates move along the f ault lines
● The focus is the point deep in the Earth’s crust where the earthquake begins
● The tremors spread out from the focus
● The epicentre is the point on the surface directly above the focus and this is the place
where tremors are the strongest
Effects of Earthquakes
Builds collapse, especially those that are closer to the epicentre
● Roads begin to crack and railway lines start to bend
● Fires may occur when gas pipes break
● Tsunamis can result from underwater earthquakes
Reducing Impact of Earthquakes
Build buildings that sway with minor earthquakes
● Scientists should examine seismographs to predict potential earthquakes
Richter Scale
Measures and determines the strength of earthquakes
Basalt is an igneous rock
● Formed when lava cools down from volcanic activity over a short period of time
● It cools very quickly and usually within a few hours
● It’s formed when the lava spreads out across the Earth’s surface
● The lava quickly solidifies when it is exposed to air
● Basalt has tiny crystals that can’t be seen by the naked eye
● Basalt can be found at the Giant’s Causeway in Co. Antrim
Granite is an igneous rock
● Formed when molten magma cools down from volcanic activity over a long period of
time
● Molten magma forces its way into the crust
● It cools very slowly in the Earth’s crust over millions of years allowing large crystals to
form
● The crystals formed include quartz and mica
● Granite eventually comes to the surface when the overlying rocks wear away
● Granite can be found in Mourne and the Wicklow Mountains
Limestone and sandstone are sedimentary rocks
Limestone
● Formed on the beds of shallow, warm seas from the skeletons of tiny sea creatures, fish
and shells
● These skeletons piled up over millions of years
● They were compressed and cemented together because of the water pressure
● Some fossils are still preserved on the rocks
● The color of limestone ranges from white to grey
● They are permeable (water can easily pass through) and laid in strata (horizontal layers
known as bedding planes)
● Limestone can be found in 31 out of the 32 counties in Ireland
● Limestone is eroded easily by carbonation because calcium carbonate (limestone)
reacts with acidic rainwater
● Uses of limestone: M anufacturers use limestone for cement
Builders use limestone to make public buildings and road surfaces Farmers use ground up limestone as soil conditioner
2. Sandstone
● Formed when large amounts of sand were worn away from the Earth’s surface and transported by the wind and rivers
● The sand was deposited on seabeds and deserts
● Layers built up, compressed and cemented to eventually form sandstone
● Sandstone varies in color from brown to red
● Sandstone can be found in the Magillicuddy Reeks and the Galtees
Marble and quartzite are metamorphic rocks
Marble
● Formed when magma forces its way into limestone which puts the limestone under great pressure and heat
● Great pressure and heats changes limestone into the rock marble
● Pure marble is white
● Marble is a hard rock and contains crystals
● Easily polished and cut
● In demand for furniture and ornaments
● Found on Rathlin Island and in Connemara
2. Quartzite
● Formed when sandstone was put under great pressure and heat in the Earth’s crust
● Usually forms during periods of folding
● Contains mainly grains of quartz packed tightly together
● Varies from grey to white
● Extremely hard rock
● Found in Croagh Patrick and Errigal
Drilling
Extracts oil or gas from an underground reservoir
● Most takes place on land
● If offshore, a pipeline on the seabed brings the fuel up
Shaft mining
Used when the resource is on or close to surface
● It’s cheap but not environmentally friendly
● Noisy and gives off dust and scars the landscape
Waves
Sizes increase with the strength of wind and fetch (length of sea)
● Swash is the water that rushes onto the shore
● Backwash is the water that returns to the sea from the shore
Destructive waves
Stormy weather
● Lots of energy and strong backwash
● Causes erosion
● Strong backwash, weaker swash
Constructive waves
Calm weather
● Limited energy
● Used to transport and deposit material
● Strong swash, weaker backswash
Wave erosion
Hydraulic action
When water hits off the coast
● Compressed air
The expanded air inside a rock can shatter the rock
● Abrasion
Rocks and stones break itself and the coast as the waves carry them
● Attrition
Rocks and stones rub off each other as the waves carry them along
How are Cliffs formed?
Vertical or steep slopes on the coast
● Destructive waves attack it by erosion, eventually forming a notch under the cliff
● As the notch gets deeper, the overhang will collapse due to pressure
● This process is repeated and the cliff retreats upstream
● As the cliff retreats, a wave cup platform will form at the bottom
● The Cliffs of Moher in Co. Clare are the best known cliffs in Ireland but Slieve League in
Co Donegal are the highest cliffs in Ireland
Bay
Wide, curved opening into the coast
● Soft rock erodes faster than harder rocks, forming a bay
● E.g Dublin Bay, Galway Bay
Headland
Neck of high land that juts out into the sea
● When hard rock is eroded slowly it sticks out as a headland
● E.g Malin Head, Mizen Head
Sea cave
A tunnel or passage in the rock at the foot of a cliff
● If the rock has a weak spot, the waves will attack it by erosion
● The crack gets larger and develops into a cave
● Sea arch: Passage that runs through the headland. If the cave is deepened and
enlarged by erosion, it may cut through to the other side of the headland to form a sea
arch
● Sea stack: Pillar of rock that’s cut off from the headland or cliff. When the waves erode
the base of the sea arch, they widen it. Eventually the roof collapses and when further
eroded, it will turn into a s ea stump
● Sea stump: Small pillar of rock that was once a sea stack
Beach
Build up of sand and shingle as a result of coastal deposition
● Swash carries its load and fine material up the shore and deposits it
● Backwash is weaker and drags some the finer material back into the sea
● Finer beach material can be found in the lower part of the beach
● Coarser beach material can be found in the upper part of the beach
● In stormy weather, the swash is strong enough to be able to hurl large stones and rocks
up past the normal tide level
Long shore drift
The waves approach the shore at an angle
● Swash moves material up the shore
● Backwash brings some material straight out
● Repeats along the shore in a zigzag fashion
Coastal protection
- Sea walls
● Concrete sea walls are built to protect coastal towns from erosion
● Sea walls have curved tops to deflect waves back into the sea
● However, the sea may also destroy these walls, especially during severe storms
● Sea walls have been built in Bray, Tramore and Galway - Boulders
● Placed at the base of soft cliffs or in from of sand dunes
● They prevent erosion because the wave’s strength is reduced
● They have been used in Youghal and Tramore
The sea and economic activity
- Recreation
● Beaches, sailing, fishing and sunbathing
● Irish resorts include Salthill and Kilkee - Transport
● Shipping ● Ferries
3. Food supply ● Fishing
● Creating more employment
Mass movement
Mass movement refers to the movement downslope of any loose material called regolith
Influences on mass movement
Gradient/Slope
The steeper the slope, the faster mass movement will occur
● Water content
Water acts as a lubricant and causes mass movement to accelerate
● Human activity
When humans cut into sides of hills or mountains, pressure from above results in mass
movement to occur
● Vegetation
Roots bind together to hold regolith together which slows down mass movement
Soil creep
Downslope movement of soil influenced by gravity
● Slowest form of mass movement and difficult to notice, unless you see the visible effects
● Soil gathers in steps called terracettes
● Poles and fences bend in the direction of the soil movement
● Walls collapse as soil piles up
● Tree trunks curve
Bog burst
Form of mudflow
● Occurs in upland areas when peat becomes saturated after heavy rainfall
● Capable of blocking roads, polluting rivers and demolishing trees
Landslide
Very rapid movement of Earth and rock down a steep slope
● Occur when a slope is unstable and after heavy rain
● Slopes become unstable when they are undercut
● Leads to destruction of roads, buildings and potentially lives
Mud flow
Moving rivers or rock, soil and water
● Fastest form of mass movement
● Debris can travel several miles
● Triggered by heavy rainfall
● Soil becomes saturated and turns into a river of mud
● Occurs after volcanic eruptions on snow covered mountains
River terms and definitions
Source: the point where a river begins
Course: the route taken by a river as it flow into the sea Tributary: a small river or stream that joins up with the river Confluence: the point at which a tributary joins the river Mouth: the point where a river enters the sea
Estuary: the part of a river mouth that is tidal
River basin: the area of land drained by a river and its tributaries Watershed: the high ground that separates one river basin and another
Stages of a river
Youthful stage ● Steep gradient ● Narrow floor ● Steep sides Mature stage ● Gentle gradient ● Wider floor ● Gently sloping sides Old stage ● Almost flat gradient ● Wide and flat floor ● Gentle sides
List the different types of water erosion, transportation and deposition
River erosion
● Hydraulic action is the force of the moving water which breaks off material from the
banks and bed of the rivers
● Abrasion is the materials carried along by the river that hits off its banks and wearing
them away
● Attrition is the material being worn down, smoothed and rounded as the particles bounce off each other
● Solution occurs when acids in the water dissolve some rocks such as limestone
The amount of erosion depends on:
● Volume - the greater the volume, the greater the load
● Velocity - the faster the river, the greater power of erosion
● Underlying rock - rivers erode soft rock faster than harder rocks
● The load - the greater the load, the greater the erosion
Transportation ● Roll
The larger particles such as pebbles and stones are rolled along the bed of the river ● Bounce
The smaller particles such as sand are bounced along the bed of the river ● Suspend
The lightest particles such as silt and clay are carried along the bed of the river ● Solution
The dissolved load such as limestone is carried in solution
Deposition
The river drops its load when:
● The river loses speed and has less energy
● The river’s volume decreases
● The river enters a flat or gently sloping plain
● The river flows into lake or sea
Features of a river
Youthful stage ● V shaped valley ● Interlocking spurs ● Waterfall Mature stage ● Wider valley ● Meanders ● Floodplain Old stage ● Oxbow lake ● Levees ● Delta
V shaped valley cuts off tips and creates interlocking spurs
This feature has narrow floors and steep sides
● The river carries stones and rocks (load) in its waters
● The force of the moving water and the grinding of the rocks cut down into the riverbed,
deepening it by vertical erosion
● Weathering breaks up the load on the valley sides
● They eventually collapse and the debris slides into the rivers
● This gives the river its v shape
● The debris is eventually worn down and transported by the river
● V shaped valleys can be seen in the youthful stage of rivers e.g. Moy, Lee, Liffey and
Slaney
A waterfall
● It’s a feature where the river flows or falls over a vertical slope
● They for when a layer of hard or resistant rock lies on top of a band of soft rock
● Over 1000’s of years, the soft rock is eroded more quickly than hard rock
● Over time, the slope becomes steeper and a waterfall is formed
● As the water drops over the waterfall, it carries its load with it
● This helps the waterfall to erode a deep hole called a plunge pool
● The falling water also cuts under the waterfall to form an overhang of hard rock
● This eventually collapses due to pressure
● The process repeats itself and the waterfall retreats upstream
● Examples of waterfalls include Ashleigh Falls in Mayo, Tore Waterfall in Kilkenny and
Glencar Falls in Sligo
Delta
A triangular shaped piece of land which is formed at the mouth of a river
● As the river enters the sea, it drops off all the remaining materials it’s carrying
● This material builds up to form a piece of new land
● The river is forced to break up into smaller distributaries
● The deposits build up above sea level to form a delta
● Deltas can be seen along the rivers Nile, Po and the Amazon
How is a sand spit formed?
Long shore drift (explain it) loses its energy and deposits the material it is carrying when it is interrupted by a sheltered bay, the material builds up overtime and extends across the bay a sand spit is formed example of a sand spit is rossbeigh strand Co Kerry
