For questions on Human Interaction with the rock cycle - go back out and click on the square for Geothermal Energy and learn the case study on Iceland.
For Landforms, we do The Giant's Causeway (basalt) & The Leinster Batholith (granite). You will find these back out in the Plate Tectonics square. We also do The Burren, a karst region as a unique geomorphological area. You will find this in the Weathering square.
Rocks Questions.pdfRocks Questions with marking-scheme.pdfIgneous Rocks
Formation of Granite and Basalt
Introduction:
Igneous rocks formation
(S) Igneous rocks are formed when molten magma or lava cools and solidifies.
(D) The location of the cooling determines whether the rock is intrusive or extrusive.
(SE) Intrusive rocks cool inside the Earth’s crust, while extrusive rocks cool on the surface. This influences the crystal size and texture of the igneous rock.
Granite as an intrusive igneous rock
(S) Granite is an intrusive igneous rock.
(D) It forms when magma cools slowly beneath the Earth’s surface.
(SE) The slow cooling allows large crystals to form, giving granite a coarse texture, which makes it durable and ideal for construction.
Granite forms at destructive plate boundaries
(S) Granite forms at destructive plate boundaries.
(D) The oceanic crust is subducted beneath the continental crust, where it melts into magma.
(SE) This magma rises, cooling slowly within the crust to form granite. Granite is often found at convergent plate boundaries.
Granite example: Wicklow Mountains
(S) An example of granite can be found in the Wicklow Mountains.
(D) The granite there formed during the Caledonian orogeny around 400 million years ago.
(SE) Over time, erosion exposed the granite, contributing to the rugged landscapes of the Wicklow Mountains.
Granite texture and composition
(S) Granite is coarse-grained, with large visible crystals.
(D) The colour ranges from pink to grey, depending on the minerals present, like quartz, feldspar, and mica.
(SE) Granite's strength and durability make it ideal for construction.
Slow cooling forms granite’s texture
(S) Granite forms when magma cools very slowly.
(D) The slow cooling allows large crystals to develop.
(SE) This slow process gives granite its characteristic texture, making it suitable for use in monuments and buildings.
Granite usage in Ireland
(S) In Ireland, granite is used in many buildings.
(D) Its durability makes it suitable for structures like monuments and countertops.
(SE) Dublin is well known for using granite in many historical buildings.
Basalt as an extrusive igneous rock
(S) Basalt is an extrusive igneous rock.
(D) It forms when lava cools quickly on the Earth’s surface.
(SE) Rapid cooling results in fine-grained basalt with small crystals.
Basalt formation at constructive plate boundaries
(S) Basalt forms at constructive plate boundaries or from volcanic activity.
(D) Lava flows out of fissures or volcanic vents, spreading over large areas.
(SE) Quick cooling forms basalt with small crystals, common in mid-ocean ridges and volcanic hotspots.
Basalt example: Giant’s Causeway
(S) An example of basalt can be found at the Giant’s Causeway.
(D) Volcanic activity around 60 million years ago caused lava to flow out and cool into hexagonal basalt columns.
(SE) These unique columns, formed as the lava contracted while cooling, are part of the UNESCO World Heritage site.
Basalt texture and composition
(S) Basalt is fine-grained and usually dark, ranging from black to grey.
(D) The rapid cooling prevents large crystals from forming, and its dark colour comes from minerals like pyroxene and feldspar.
(SE) Basalt's fine-grained texture makes it resistant to weathering.
Basalt usage in construction
(S) Basalt is used in road-building and construction.
(D) Its durability and resistance to weathering make it ideal for infrastructure projects.
(SE) In Ireland, basalt is commonly used as a building material for roads and foundations.
Basalt forms quickly on the surface
(S) Basalt forms quickly when lava cools on the surface.
(D) The rapid cooling results in a smooth, dense texture.
(SE) Its hardness makes it suitable for creating durable roads and pavements.
Basalt and granite in construction
(S) Basalt and granite are both commonly used in construction.
(D) Granite's coarse texture and strength make it suitable for monuments, while basalt's smooth texture is ideal for roads.
(SE) Both rocks contribute to the development of infrastructure in Ireland.
Diagram
A relevant diagram is necessary to get full marks. Ensure it has a title, a frame, and labels. Keep it simple, don’t waste time, it is only worth 2 marks.
Condensed:Formation of Granite and Basalt
For Timed Exam
Igneous Rocks Formation: Igneous rocks form when molten magma or lava cools and solidifies, with the cooling location determining if the rock is intrusive or extrusive, influencing crystal size and texture.
Granite as an Intrusive Igneous Rock: Granite is an intrusive igneous rock formed when magma cools slowly beneath the Earth's surface, allowing large crystals to develop, resulting in a coarse texture that is durable for construction.
Granite Formation at Destructive Plate Boundaries: Granite forms at destructive plate boundaries where the oceanic crust subducts beneath the continental crust, melting into magma that rises and cools slowly, typically found at convergent boundaries.
Granite Example: Wicklow Mountains: The granite in the Wicklow Mountains, formed during the Caledonian orogeny around 400 million years ago, has been exposed through erosion, contributing to the region's rugged landscape.
Granite Texture and Composition: Granite has a coarse-grained texture with large visible crystals, varying in colour from pink to grey due to minerals like quartz, feldspar, and mica, making it strong and durable for construction.
Slow Cooling Forms Granite’s Texture: The slow cooling of magma allows large crystals to develop in granite, giving it a characteristic texture suitable for monuments and buildings.
Granite Usage in Ireland: In Ireland, granite is widely used in construction, including historical buildings in Dublin, due to its durability and suitability for structures like monuments and countertops.
Basalt as an Extrusive Igneous Rock: Basalt is an extrusive igneous rock formed when lava cools quickly on the Earth’s surface, resulting in a fine-grained texture with small crystals.
Basalt Formation at Constructive Plate Boundaries: Basalt forms at constructive plate boundaries or volcanic activity, where lava spreads out and cools rapidly, common in mid-ocean ridges and volcanic hotspots.
Basalt Example: Giant’s Causeway: The Giant’s Causeway features basalt formed from volcanic activity 60 million years ago, creating unique hexagonal columns as lava cooled and contracted, now a UNESCO World Heritage site.
Basalt Texture and Composition: Basalt is fine-grained and dark, ranging from black to grey, with its rapid cooling preventing large crystal formation, and its colour resulting from minerals like pyroxene and feldspar.
Basalt Usage in Construction: Basalt is used in road-building and construction due to its durability and resistance to weathering, making it ideal for infrastructure projects in Ireland.
Basalt Forms Quickly on the Surface: Basalt forms quickly when lava cools on the surface, resulting in a smooth, dense texture that is suitable for durable roads and pavements.
Basalt and Granite in Construction: Both basalt and granite are commonly used in construction, with granite's coarse texture ideal for monuments and basalt's smooth texture suitable for roads, contributing to Ireland's infrastructure.
Diagram: A relevant diagram illustrating the formation of granite and basalt is essential for full marks; ensure it is clear and simple with a title and labels.
Sedimentary Rocks
Exam-Style Answer: Formation of Limestone and Sandstone
Limestone is a sedimentary rock made from the remains of marine organisms
(S) These remains, such as shells and skeletons, accumulate on the seafloor.
(D) Over millions of years, they form thick layers called strata.
(SE) This leads to the formation of limestone layers.
As more layers build up, the weight compacts the sediments
(S) Calcite from the organisms acts as a natural cement, binding the particles together.
(D) This process, called lithification, turns soft sediments into solid limestone.
(SE) This forms compact limestone rock layers.
Carboniferous limestone in Ireland was formed around 350 million years ago
(S) During this time, Ireland was covered by shallow tropical seas.
(D) The Burren in Co. Clare is an exposed example of Carboniferous limestone.
(SE) This period shaped much of Ireland’s limestone geology.
Limestone is composed mostly of calcium carbonate (CaCO₃)
(S) This makes it susceptible to chemical weathering through carbonation.
(D) This reaction helps create features like limestone pavements.
(SE) This process shapes karst landscapes like the Burren.
Carbonation occurs when rainwater absorbs CO₂ from the atmosphere, forming weak carbonic acid
(S) This acid reacts with calcium carbonate in limestone, dissolving it.
(D) This leads to features like grikes and clints.
(SE) The Burren's landscape is a prime example of this process.
In Ireland, limestone can also form distinctive underground features
(S) Carbonation can create caves, stalactites, and stalagmites over time.
(D) An example is Aillwee Cave in Co. Clare.
(SE) These underground features are common in karst regions.
Limestone is a pervious rock, meaning water can pass through its joints and bedding planes
(S) Unlike porous rocks, limestone allows water to flow through cracks.
(D) This contributes to the development of karst landscapes.
(SE) Water seepage through limestone forms underground features.
Sandstone is a sedimentary rock made from sand-sized particles of other rocks
(S) These particles are transported by rivers and deposited in layers.
(D) Over time, they are compacted into sandstone.
(SE) Sandstone layers form in sedimentary environments like lakes or deserts.
The process of lithification compacts the sand particles, and they are cemented by minerals like silica
(S) This binding agent solidifies the rock.
(D) This gives sandstone strength and durability.
(SE) Sandstone is often durable and widely used as a building material.
Old Red Sandstone in Ireland was formed around 350-400 million years ago
(S) At this time, Ireland lay in a desert environment 30 degrees south of the equator.
(D) Huge rivers transported sediment across the landscape.
(SE) This formed the Old Red Sandstone found in Munster today.
The Munster Ridge and Valley province is an example of where Old Red Sandstone is found
(S) It was formed as large rivers flowed through ancient desert plains.
(D) Sand was deposited and compacted into sandstone.
(SE) This type of sandstone is prevalent in Cork and Kerry.
Sandstone is a porous rock, meaning it can store water, oil, or gas between grains
(S) This property makes sandstone a good reservoir rock.
(D) It is also durable, making it useful in construction.
(SE) Sandstone is often used in building materials.
Red sandstone gets its colour from iron oxide
(S) The presence of iron turns the sandstone reddish as it oxidizes.
(D) This distinctive red colour can be seen in Munster sandstone.
(SE) This gives the rock its iconic red hue, seen in the Munster region.
Sandstone was used as a building material in Ireland due to its strength and availability
(S) Many old buildings in Munster are constructed from local sandstone.
(D) It remains a popular choice for stone walls and structures.
(SE) Sandstone is a strong, durable building material.
Diagram:
A relevant diagram is necessary to get full 30 marks. Ensure it has a title, a frame, and labels. Keep it simple, don't waste time, it is only worth 2 marks.
Limestone is a sedimentary rock formed from marine remains. Shells and skeletons build up on the seabed. Over time, they form layers called strata.
As more layers build up, the weight compacts the sediments. Calcite acts as a natural cement between particles. This turns soft sediment into solid limestone.
Carboniferous limestone in Ireland formed 350 million years ago. Ireland was covered by warm tropical seas. The Burren in Clare is a good example.
Limestone is made of calcium carbonate (CaCO₃). It’s vulnerable to chemical weathering by carbonation. This process shapes landscapes like the Burren.
Rainwater mixes with CO₂ to form weak carbonic acid. This acid dissolves calcium carbonate in limestone. Features like grikes and clints form.
Carbonation can also form underground features. These include caves, stalactites, and stalagmites. Aillwee Cave in Clare is an example.
Limestone is pervious, meaning water can pass through joints and cracks. This helps shape karst landscapes. It allows underground features to develop.
Sandstone forms from compacted sand-sized particles. These are carried by rivers and deposited in layers. Over time, they harden into sandstone.
Lithification cements sand particles together. Minerals like silica act as binding agents. This gives sandstone its strength and durability.
Old Red Sandstone formed 350–400 million years ago in a desert. Rivers carried and dropped sand across the land. This created sandstone in Munster.
In the Munster Ridge and Valley province, rivers shaped the landscape. Sand built up and compacted into rock. This sandstone is found in Cork and Kerry.
Sandstone is a porous rock. It can store water, oil, or gas between grains. This makes it useful in construction and energy.
Red sandstone gets its colour from iron oxide. The iron turns the rock reddish through oxidation. This colour is common in Munster's landscape.
Sandstone was used as a building material in Ireland. It is strong and widely available. Many old Munster buildings are made from local sandstone.
Draw and label a diagram showing limestone or sandstone formation. Include a title, frame, and clear labels. This is worth 2 marks in the exam.
Metmorphic Rocks
Exam-Style Answer: Formation of Marble and Quartzite
Metamorphism Overview:
(S) Metamorphic rocks form when existing igneous or sedimentary rocks are changed by heat, pressure, or both.
(D) This process is called metamorphism, and it occurs deep within the Earth's crust.
(SE) There are two types of metamorphism: thermal and regional.
Marble Formation:
(S) Marble forms from limestone through contact metamorphism.
(D) Limestone is exposed to intense heat from nearby magma, causing it to recrystallise into a harder rock.
(SE) This process changes limestone into a dense, crystalline marble.
(S) Connemara Marble, found in Co. Galway, is an Irish example.
(D) This marble has a green colour, caused by serpentine minerals within the limestone.
(SE) It is widely used for decorative purposes and construction.
(S) Contact metamorphism occurs when magma heats surrounding rock without melting it.
(D) This heat causes the calcite in the limestone to recrystallise into interlocking crystals, making marble harder and more durable than limestone.
(SE) The dense structure of marble improves its resistance to weathering.
(S) Impurities in the limestone affect the colour of the marble.
(D) Pure limestone forms white marble, while impurities like iron, serpentine, and clay cause marble to vary in colour.
(SE) For example, the famous Connemara Marble is green due to serpentine minerals.
(S) Marble is much stronger than limestone due to recrystallisation.
(D) This process creates interlocking crystals that give marble its durability.
(SE) This makes marble popular for sculptures and building materials.
(S) Marble has been used for centuries in artistic and architectural projects.
(D) Its durability and aesthetic appeal make it suitable for use in monuments and classical buildings.
(SE) The Taj Mahal in India is a famous example built using white marble.
Quartzite Formation:
(S) Quartzite forms from sandstone through thermal metamorphism.
(D) When sandstone is exposed to high temperatures, usually from magma, silica in the rock recrystallises, bonding the quartz grains together.
(SE) This process forms quartzite, a much harder rock.
(S) Quartzite can be found in the Sugarloaf Mountains in Co. Wicklow and Croagh Patrick in Co. Mayo.
(D) These areas experienced metamorphism during the Caledonian mountain-building period.
(SE) The quartzite in these regions is highly resistant to erosion.
(S) Thermal metamorphism changes sandstone into a much denser rock.
(D) The spaces between the grains of quartz are filled with silica, and the heat fuses them together.
(SE) This process creates a rock that is much more durable than sandstone.
(S) Quartzite is known for its light colours, often white or grey.
(D) The recrystallisation of quartz in sandstone results in this light appearance.
(SE) Its strength and appearance make it valuable in construction.
(S) Quartzite is much harder and more resistant to weathering than sandstone.
(D) This makes it an ideal material for use in construction, especially in outdoor environments.
(SE) Its resistance to erosion makes it common on mountain peaks.
(S) Quartzite is often used in road construction.
(D) Its toughness makes it ideal for use as aggregate in road surfaces and other infrastructure.
(SE) The durability of quartzite extends the lifespan of roads and reduces maintenance costs.
(S) Quartzite is commonly used in the production of countertops and tiles.
(D) Due to its hardness and resistance to scratches, quartzite is a popular material for indoor and outdoor surfaces.
(SE) Its durability and aesthetic appeal make it a sought-after material in home design and landscaping.
Diagram A relevant diagram is necessary to get full marks. Ensure it has a title, a frame, and labels. Keep it simple, don’t waste time, it is only worth 2 marks.
Condensed Exam-Style Answers: Metamorphism and Rock Formation for Timed Exam
Metamorphism Overview: Metamorphic rocks form when existing igneous or sedimentary rocks are altered by heat, pressure, or both deep within the Earth's crust, a process known as metamorphism, which can be classified into thermal and regional types.
Marble Formation: Marble forms from limestone through contact metamorphism, where intense heat from nearby magma causes the limestone to recrystallise into a denser, harder rock.
Irish Example - Connemara Marble: Connemara Marble from Co. Galway, known for its green colour due to serpentine minerals, is widely used for decorative purposes and construction.
Contact Metamorphism: Contact metamorphism occurs when magma heats surrounding rock without melting it, causing calcite in the limestone to recrystallise into interlocking crystals, enhancing marble's hardness and durability.
Impurities Affecting Marble Colour: Impurities in limestone affect marble colour; pure limestone yields white marble, while minerals like iron and serpentine create variations, as seen in the green Connemara Marble.
Strength of Marble: Marble is significantly stronger than limestone due to recrystallisation, which forms interlocking crystals, making it popular for sculptures and building materials.
Historical Use of Marble: Marble has been used for centuries in artistic and architectural projects due to its durability and aesthetic appeal, exemplified by the Taj Mahal, which is built with white marble.
Quartzite Formation: Quartzite forms from sandstone through thermal metamorphism, where high temperatures cause silica to recrystallise, bonding quartz grains together and resulting in a much harder rock.
Quartzite Locations: Quartzite can be found in the Sugarloaf Mountains in Co. Wicklow and Croagh Patrick in Co. Mayo, formed during the Caledonian mountain-building period, making it highly resistant to erosion.
Density of Quartzite: Thermal metamorphism changes sandstone into denser quartzite by filling spaces between quartz grains with silica, fusing them together for enhanced durability.
Colour of Quartzite: Quartzite typically has light colours, often white or grey, due to the recrystallisation of quartz, making it valuable in construction for its strength and appearance.
Weathering Resistance of Quartzite: Quartzite is much harder and more resistant to weathering than sandstone, making it ideal for construction, especially in outdoor settings like mountain peaks.
Use in Road Construction: Quartzite's toughness makes it suitable for road construction as aggregate, extending the lifespan of roads and reducing maintenance costs.
Quartzite in Countertops and Tiles: Quartzite's hardness and scratch resistance make it popular for countertops and tiles, valued in home design and landscaping for its durability and aesthetic appeal.
Diagram: A relevant diagram illustrating metamorphism and rock formation is essential for full marks; ensure it is clear with a title and labels.
