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Flashcards in Rocks And Fossils Deck (43)
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Define the lithosphere

The rigid outer part of the earth consisting of the crust and upper mantle.


Define the asthenosphere

The upper layer of the earths mantle, below the lithosphere


Describe the thickness and state of earths crust

Thickness- the thickness of the earths crust is like the skin of an apple, it is incredibly thin
State- solid


Describe the thickness and state of the mantle

Thickness- It is 2900 km thick and makes up 84% of earths volume
State- mostly solid


Describe the thickness and state of the outer core

Thickness- it is 2200 km thick


Describe the thickness and state of the inner core

Thickness-it has a radius of 1220 km


Define the term weathering

Wear away or change the appearance or texture of something by long exposure of the atmosphere


Define the term physical weathering

The geological process of rocks breaking apart without changing their chemical position.


List examples of physical weathering

-ice wedging
-plant roots
Swiftly moving water


Explain spalling and how it contributes to weathering

Spalling is a physical weathering process that occurs in areas where the days are very hot and the nights are very cold. The large temperature changes cause the outermost layers to peel off


Explain ice wedging and how it contributes to weathering

Ice wedging is a physical weathering process that occurs when water collects in a crack of a rock and freezes at night, the ice expands and forces the crack wider, the ice melts and then that night the ice forms and forces the crack even wider.


Define the term chemical weathering

Chemical weathering causes rocks to break down in smaller prices by chemicals in the environment changing their composition through chemical reactions


List some examples of chemical weathering



Explain the cause of acid rain and describe its effects

Acid rain is caused when raindrops dissolve pollution in the air, this increased the acidity of rain. It effects rocks (it dissolves the rocks) such as limestone and marble. It causes damage to statues and buildings and can also kill plants.


Define the term erosion and describe ways it can occur

Erosion is the process where small rock fragments are moved and carried away to another area. It can occur when wind blows around particles of sand and dust
Moving water washes away stones, sand and mud
Glaciers carve away soil and rock as it moves
Gravity causes landslides or for wet soil to slide down a steep slope


List landforms and landscapes that are caused by erosion

River beds
Sandy dunes
Sand banks
Sea stacks
Rock platforms


Identify ways erosion can be prevented on farms

Plant trees and grass
Retaining walls
Control run off-put in drainage


Identify ways erosion can be prevented at the beach

Build sea walls
Build revetments
Build jetties along the shoreline


Identify ways erosion can be prevented in cities

Restraining walls
Planting trees and grass


How are sedimentary rocks formed?

Sediments such as sand and silt are deposited in layers, the build up of layers is called sedimentation, over thousands of years the layers become compacted or the grain become cemented together by dissolved compounds


What are the features of sedimentary rocks

Often have layers
Made of lots of small grains
Often porous
Can be soft and crumbly
Can contain fossils


How are igneous rocks formed

Igneous rocks are formed when magma cool and solidifies. Slow cooling lava has large crystals and lava that has been cooled quickly has small crystals


What are the features of igneous rocks

Contain interlocking crystals
Strong and hard
Crystals area arranged in random patterns
Can have crystals of different sizes
Can never contain fossils


How are metamorphic rocks formed?

Metamorphic rocks are created by the physical or chemical alteration by heat or pressure of an existing igneous or sedimentary material into a fender form


What are the features of metamorphic rocks

Often contain layers of crystals
Denser and harder than sedimentary rocks
Often show wavy or zig zag patterns


Define the difference between magma and lava

Magma is found BELOW the surface of the earth and lava is found ON the surface of the earth


Define the difference between active, dormant and extinct volcanoes

An active volcano may erupt at any time, a dormant volcano hasn’t erupted in ages but still might and an extinct volcano will not erupt anymore


Outline how the cooling rate of magma impacts crystal size in rocks

If the magma cools slowly it makes big crystals and if it cools fast it makes small crystals


Describe the features of intrusive igneous rocks

Large, well formed crystals
Magma cools slowly
Are formed deep in a volcano
Have granite and grabbing in them


Describe the features of extrusive igneous rocks

Small crystals
Magma cools quickly
Formed near the top of the volcano
Contain basalt and obsidian