Rocks Flashcards
3 rock types
Igneous
Sedimentary
Metamorphic
Formation of igneous rock in general
Cooling and solidification of magma or lava.
Intrusive/plutonic are formed beneath crust eg granite
Extrusive/ volcanic are formed on the crust eg basalt
Hypabyssal form just below the surface eg dolerite
Example of a plutonic/intrusive igneous rock
Granite
Example of an extrusive/ volcanic igneous rock
Basalt
Example of a hypabyssal igneous rock
Dolerite
Minerals in granite
Feldspar
Mica
Quartz
Colour of granite
Dark grey
How does granite form
At convergent boundaries, where two plates collide
Fold mountains made
Magma rises up under folds
Magma slowly cools
Sedimentary above changes to metamorphic by heat
Metamorphic protects granite
Example of granite rock in Ireland
Leinster Batholith, Dublin Wicklow mountains
Uses of granite
Building stone eg GPO made of granite
When broken down it forms kaolin (clay for porcelain)
What’s the most common rock on earth
Basalt
Minerals in basalt
Pyroxene and olivine
Colour of basalt
Dark brown, black
Where is basalt being created
Mid ocean ridges
Mid Atlantic ridge
How does basalt form
When plates separate
Magma rises
Cools quickly on surface - small crystals
Example of basalt in Ireland
Antrim Derry plateau
Basalt cooled and split into a series of hexagonal shapes causing the giants causeway in Antrim
Use of basalt
Building industry
Road filler
Floor tiles
How are sedimentary rocks defined
Parent material
Two types of sedimentary rock
Inorganic (made of fragments of other rocks eg sandstone)
Organic (made of fossils from plants or animals eg limestone)
Formation of sedimentary rock in general
Sediments of rock or fossils are deposited in layers called strata,
Layers are crushed and compacted by their own weight or weight of water
Layers are cemented together by minerals
How is oil created in rock
When sea creatures are compacted
What is lithification.
The compacting and cementation of sedimentary rock
How common is sandstone in Ireland
2nd most common
Is sandstone organic or inorganic
Inorganic, made of grains of quartz (sand)
How is sandstone made
Layers of quartz build up beneath a shallow sea, this quartz has been deposited by flood or wind.
Strata were cemented together by the weight of the water and lithification occurred and iron and silica cemented the strata into rock.
The iron oxide gives Irish sandstone it’s reddish appearance
What is Irish sandstone known as due to addition of iron oxide
Old red sandstone
Where can old red sandstone be found
Munster ridge and valley region.
What’s the most common rock in Ireland
Limestone.
Is limestone organic or inorganic
Organic, made of fish fossils
How is limestone formed
Sea creatures die and fall to the bed of the sea
The ,layers build up and eventually are compressed by the weight of the seawater
Compression removed water and air.
Lithification occurred as calcium carbonate in sea creatures bones cemented the rock together
Minerals in limestone
Calcium carbonate
Minerals in sandstone
Iron
Silica
Is limestone permeable
Yes
Colour of limestone
Greg usually
Example of limestone in Ireland
Karst landscape the burren co Clare
How was the burren formed
Under the Atlantic Ocean and was protected by a layer of soil until large glaciers scraped it away during the ice age
What’s the parent material
Material that was compacted to make sedimentary rock
What’s are strata
Layers of rock
What does permeable mean
Allows water to pass through it
What are metamorphic rock
Igneous and sedimentary rock that change form chemically (what they’re made of) or physically (how they look) due to intense heat and/or pressure
What conditions can metamorphism occur at
Above 200° Celsius
Above 300 megapascals of pressure
3 types of metamorphism
Thermal/contact metamorphism (changed by heat) Regional metamorphism (changed but heat and pressure) Dynamic metamorphism (changed by great pressure)
Parent rock of marble
Limestone or chalk
Type of metamorphism that makes marble
Regional metamorphism
How is marble made
Limestone is destroyed by great heat and pressure. Large crystals develop changing it physically
What colour is pure marble
White eg Carrara marble in Italy
How can marble be different colours
Impurities in parent rock
Eg serpentine in limestone makes green marble eg in Connemara Galway
Iron oxide in limestone makes red marble eg in cork
Uses of marble
Sculptures
As it’s soft
Two examples of metamorphic rock
Marble and quartzite
Two examples of sedimentary rock
Limestone and sandstone
Two examples of igneous rock
Granite and basalt
What is the parent rock of quartzite
Sandstone
How is quartzite made
Sandstone came into contact with magma.
Magma filled gaps between grains of quartz with Silica.
Heats and pressure (regional metamorphism) caused silica and quartz to join.
What is the structure of quartzite like
No pores
Very hard to erode
Where is quartzite in Ireland
Cap on many mountains eg sugarloaf Wicklow
How many active quarries are there in Ireland
500
3 methods of rock quarrying
Plug and feather method
Channeling method
Explosives
What happens in the plug and feather method
A hole is drilled into rock and wedges are pushed in between the bedding planes. Making big slabs of rock. Used in sedimentary rock
How does the channeling method work
Huge slices of rock are cut off by a large rotating disk eg marble
How do explosives quarry the rock
Holes are drilled into rock and dynamite is placed inside. Rock is ballestee into pieces and gathered up and crushed and dusted fo road fillers and concrete
How many people employed in quarrying
15000
Positive impacts of quarrying
15000 people employed in the industry €3 billion worth Own supply of materials for constructions and achieved national development plan Agricultural limestone Infrastructure improved in local areas
Negative impacts of quarrying
Noisy and dusty Tallaght - roadstones Belgard quarry - peoples homes are damaged, driveways sinking and dust clouds created Constant heavy traffic Visual pollution Disused quarries become illegal dumps
Size of Antrim Derry plateau
4000km squared
When did Antrim Derry plateau begin to form
65 million years ago when Eurasian and North American plates began to diverge
How many hexagons in giants causeway
600,000
How tall is giants causeway
350m