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KS3 Rocks
KS3 Rocks and Weathering
Question | Answer |
---|---|
What are the main types of rocks | igneous, metamorphic and sedimentary rocks |
How long does it take to “make” a rock? | millions of years |
What are rocks made up of? | minerals |
What is the earth’s crust made up of? | rock |
Describe the appearance of a sedimentary rock | they are grains stuck together |
State an example of a sedimentary rock | Sandstone or Limestone |
How does sedimentary rock form? (4 steps) | Deposition, Burial, Compression, Cementation (aka Compaction). |
Explain what a strata is | it is a layer of the same sedimentary rock. It can be up to a few metres high! |
Explain why you do not find fossils in igneous or metamorphic rocks | Because in igneous rock the lava would have burned the bones and if there were fossils in the sedimentary rock that became metamorphic, the bones would have been crushed under the extreme pressure |
Describe what a fossil is | the remains of a living thing that existed millions of years ago |
In which type of rock do we (mostly) find fossils? | in sedimentary rock |
Describe how is igneous rock formed? | It is formed by lava/magma cooling down. |
What does B…I…I…I...G…S stand for? | B = BIG; I = INSIDE;I = INTRUSIVE;I = IGNEOUS; G = GRANITE; S = SLOW COOLING |
Describe the appearance of igneous rocks | Igneous rocks contain randomly arranged interlocking crystals. |
What does an igneous rock look like | crystals |
State an example of a igneous rock | Granite or Basalt |
Which igneous rock is intrusive: Granite or Basalt? | Granite |
In an igneous rock are crystals bigger when it is cooled down fast or slowly | slowly |
Describe how metamorphic rocks are formed | they are formed in extreme pressure |
State an example of a metamorphic rock | Marble or Slate |
Describe what might you see in metamorphic rock? | You can see different layers and shiny crystals. |
Name the (likely) type of rock that has flat layers? | Metamorphic. |
Describe what happens to crystals during the formation of metamorphic rocks? | they line up in the same direction |
Name the four types of weathering? | Onion skin, freeze-thaw, chemical weathering and biological weathering. |
Explain what happens during chemical weathering | it is when rain falls on limestone etc. (1) and makes it dissolve (1) |
Name two rocks that are badly affected by acid rain. Explain why | Limestone and Marble, because both are made of Calcium carbonate |
When acid rain (Nitric Acid) falls on Limestone (Calcium Carbonate), what is the word equation for the reaction? | Nitric Acid + Calcium Carbonate Calcium Nitrate + Water + Carbon Dioxide |
State which rocks are affected by chemical weathering? | Rocks that contain the mineral Carbonate |
State the gas is given off when Limestone is dissolved by rain? | Carbon Dioxide |
Describe what is onion skin weathering | rock is repeatedly subjected to heat and cold. Outer layer expands in heat. Outer layer contracts in cold. Outer layer of rock peels off. |
Describe what is a freeze thaw weathering | processes induced by stresses created by the freezing of water into ice. |
Explain why rocks can be broken down by the freeze-thaw effect | Water gets into a crack(1);during the night, the water freezes(1) and expands(1); the crack gets bigger(1) |
Explain what happens in biological weathering? | Lichen grows on the rocks; lichen produces acid (1) that dissolves the rock (1) |
Explain what happens to rocks in deserts? | In hot temperatures the rock expand and in cold temperatures the particles contract. This is onion-skin. |
Describe what happens to the water when it is hot? | It expands. |
Describe what happens to the water when it is cold? | The water freezes AND expands. |
Define erosion? | Erosion is when rocks are moved and tumble against each other as the water, the wind or ice moves the bits of rocks along. Rocks get worn away. |
Describe what happens to rocks during erosion | they get smaller and rounder |
Name three things that cause erosion | wind, ice and water |
Describe what happens during deposition | sediments settle at the bottom of the sea and build up layers/strata |
Describe what happens during compaction | The sediments at the top squash the sediments at the bottom and the water and crystals are squeezed out from between the pieces of rock. The crystals form glue that sticks the pieces of rocks together. This whole process takes many years. |
What is another form of limestone? | Chalk is a soft white form of limestone. |
Explain how fossils of sea animals can be found at the top of the Himalaya, yet the sea is miles away? | When two tectonic plates collided, layers sedimentary rocks got lifted up |
Explain how are metamorphic rocks brought to the earth’s surface? | Uplift and erosion help bring the metamorphic rocks to the earth’s surface. |
State what limestone is mixed with to make glass? | Sand |
Is coal a sedimentary rock? | Yes, it is made from the remains of plants that died millions of years ago and then got covered by sand |
State the pH of normal rain. Is it acidic, neutral or alkaline? | pH6, slightly acidic |
What is the name of the molten rock found inside the Earth | Magma is the molten rock inside the earth (lava is the name when magma erupts outside the Earth's crust) |
What is the type of weathering most likely to happens in Mountains? | Freeze-thaw (because there will be water and the temperature could fall below 0C) |