Rocks and the rock cycle Flashcards
What are rocks?
Rocks are natural materials that are the solids that make up the earth’s crust. They are mixtures of minerals so their composition varies depending on where and when they were formed.
What are minerals?
Minerals are natural compounds that make up rocks. They have a fixed composition because they are single compounds.
If a rock has interlocking grains, is it porous? Yes/No
No it isn’t very porous because there are not many gaps for water to collect in and if there are any gaps they are small.
If a rock has lots of gaps and is quite crumbly, is it porous? Yes/No
Yes, because there are a lot of gaps where water can collect and the gaps are big so more water can collect in them.
Name the three types of weathering.
Physical
Chemical
Biological
Explain physical weathering.
Physical weathering is caused by the effects or changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water.
List the two main types of physical weathering and explain them.
Freeze-thaw - This occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.
Temperature - Temperature changes can cause weathering. The rock expands during the day when it is hot and contracts at night when it is cold. The rock eventually breaks apart.
Explain chemical weathering.
Rainwater is naturally acid because of gases dissolved in it. This acid rain reacts with the minerals in the rock, causing the rock to be weathered. The acid rain can also be caused by burning fossil fuels.
Explain biological weathering.
Plant roots can case biological weathering. The plant
roots grow into small cracks in the rocks, and push the sides of the cracks apart when they grow bigger. Slowly causing the rock to break.
How does weathering and erosion provide the material for making sedimentary rocks?
When the rocks are weathered and broken apart they are carried to the sea and subjected to lots of pressure as more rocks pile on top.
How are sedimentary rocks formed?
Small fragments of rocks formed by weathering are transported by rivers to the sea. They are deposited in layers on the sea bed. Over millions of years the grains are cemented together by minerals and the pressure of layers above.
Give an example of a sedimentary rock.
Chalk Sandstone Limestone Coal Conglomerate
Give the properties of a sedimentary rock.
Relatively soft, crumbly, rounded grains
How are igneous rocks formed?
Igneous rocks form when molten rock cools and solidifies. This can happen quickly, when lava from volcanoes cools and forms rocks with small crystals. This can happen slowly when magma cool underground forming big crystals.
What are the properties of igneous rocks?
very hard, contain crystals and have no fossils.
