Chapter 5-8 Flashcards
How are igneous rocks formed?
When magma or lava cools down.
How was sedimentary rock formed?
Sedimentary rock was formed when existing rocks, plant and animal life were worn down and compressed to form rocks. This mainly happens under water.
How are metamorphic rocks formed?
When existing rocks are changed by great heat and/or pressure.
What are some examples of sedimentary rock?
- sandstone
- limestone
How is sandstone formed, what are its uses and where can you find it?
- Sandstone is formed when layers of sand are compressed and cemented into sandstone by pressure.
- sandstone is used in buildings and in road surfaces
- you can find sandstone in Macgillycuddy’s creek in Co. Kerry
How is limestone formed, what are it’s uses and where can you find it?
- limestone is formed from the layers of shells and bones at the bottom of the sea. The weight of these layers compresses the shells and bones into limestone.
- limestone is used in buildings, roads and cement
- limestone covers about 40% of Ireland but you can also find it in the burren
What are examples of metamorphic rocks?
- marble
- quartzite
How was marble formed, what is it used for and where can you find it?
- Marble was formed when limestone was changed by great heat and pressure.
- used in sculptures, kitchen worktops and headstones
- Connemara marble
What are the three rock groups?
- igneous
- sedimentary
- metamorphic
How is quarzite formed, when is it used and where are examples of it?
- quarzite is formed when sandstone is changed by a great heat or pressure
- quarzite is used in glass-making and road surfaces
- sugarloaf mountain
What are some examples of metamorphic rock?
- marble
- quarzite
- slate
What is the extraction of rocks and minerals?
The way in which the rocks and minerals are mined or taken out of the earth
Open-cast mining/quarrying
Used when the rocks and minerals are close to the surface, used for sand, gravel and limestone
Shaft mining
Used to extract rocks and minerals that are deeper underground e.g coal
Advantages of quarrying
- provides employment both in the extraction and the transport industry
- raw materials used in industry e.g sand and gravel in construction
- the local council gets money from the quarry companies
- local roads are improved for heavy traffic
Disadvantages of quarrying
- noise pollution from heavy lorries and from blasting in the quarries
- parts of the countryside are destroyed
- loss of farmland
- old, abandoned quarries are quite dangerous when flooded
What is denudation?
The wearing down of the surface of the earth, it is done by weathering and erosion
What is weathering?
The breakdown of rock, usually by the forces of weather. The broken rock lies where is has been broken. There are 2 types; mechanical and chemical
What is erosion?
The wearing away of rock, the transportation of that rock and its deposition. Erosion is carried out by rivers, the sea, glaciers and wind
What is mechanical weathering?
Mechanical weathering occurs when rocks are broken apart by physical force applied by frost and plants etc.
Where does freeze-thaw action occur?
In colder climates or high up in mountains, occurs when:
- temp rises above and falls below 0
- where there is precipitation
What is scree?
Broken rock pieces that lay at the bottom of slopes after freeze-thaw action has occurred
What is an example of mechanical weathering in a hot climate?
Exfoliation
Where does exfoliation occur?
In hot climates where the different between the temperatures during the day and the night are high
How does exfoliation work?
The outer layer of rock is heated during the day and it expands, the rock then contracts during the cold nights. This continues day after day until eventually the outer layer of rock cracks away from the inner layers
What is chemical weathering?
Chemical weathering occurs when a chemical change in the rocks causes them to dissolve
What is carbonation?
Limestone is dissolved by carbon dioxide in rainwater
How does carbonation occur?
When rain falls it takes in carbon dioxide from the air, the carbon dioxide acts like a weak acid to open cracks and joints in the limestone by dissolving the limestone
Where can the effects of carbonation be seen?
The burren Co. Clare
What does it mea that limestone in permeable?
This means rainwater can pass through it
What is a karst landscape?
A landscape formed from the dissolution of soluble rocks, it is characterised by underground features such as caves
What is a limestone pavement?
The bare surface of the limestone divided into blocks
What are clints?
The blocks of limestone that form the limestone pavement
What are grimes?
The gaps between the blocks. Joints in the rock are opened wider by the process of carbonation
What are swallow holes/sink holes?
Opening in the surface of the limestone through which the rivers disappear underground
What are the surface features of a karst landscape?
- limestone payments (clints+grikes)
- swallow holes
What are the underground features of a karst landscape?
–stalactites
- stalagmites
- pillars/columns
What are stalactites?
Cone-shaped deposits of minerals that hand down from the ceiling of a limestone cave
How are stalactites formed?
They are formed when water drops containing dissolved limestone (calcite) form on the roof of the cave When the water evaporates, it leaves behind calcite. Over time these deposits develop into stalactites