Rocks And Fossils Flashcards
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
State-liquid
Describe the thickness and state of the inner core
Thickness-it has a radius of 1220 km
State-solid
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
-spalling
-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
- Acids
- Rust
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 Tributaries Sandy dunes Sand banks Cliffs 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
Identify examples of minerals
Bauxite Haematite Cinnabar Sphalerite Rutile Galena
Identify examples of valuable minerals (gemstones)
Diamonds Ruby’s Emerald Sapphires Opal Amethyst
Identify and describe the properties that can be used to identify minerals
Colour-the external colour of a mineral
Lustre-the appearance of a mineral when placed under a light source
Streak- the colour produced when a mineral is scratched onto a white streak plate or powdered
Hardness-the strength of a mineral
Cleaver-the tendency of a mineral to break along flat planar surfaces
Define the term fossil
The remains or impressions of plants or animals embedded in rock
Outline the conditions under which fossils form
The plant or animal dies and is buried by sediment
The soft parts decay
The skeleton dissolves leaving a mould
Minerals replace the mould creating a ‘rock skeleton’
Outline the use and process of comparative dating of fossils
Use- to determine the age of the fossil
Process- comparing it to other rocks in the area
Define the term ore
Ore is a mineral with a large amount of a useful metal in it
Give examples of ore and their useful mineral component
Bauxite and aluminium
Galena and lead
Sphalerite and zinc
Outline the basic strategy for processing ore from mining to refining
The ore is grinded up and then in some cases mixed with other metals or chemicals then smelted into a liquid and then poured into a cast or put into big rolls then sold
Discuss factors that need to be considered before a mining project begins
Checking that their not going to kill and plants or animals
Make sure that their are no poisonous chemicals under the ground
Make sure that there won’t be any run off that contaminate other places
Make sure what your mining is actually there
Check with the owner of the land
Identify advantages of mining
Provides necessary materials for modern living
Provide materials to make fuels or for electricity generation
Contribution to the economy
Creates jobs and provides their families with income
Identify disadvantages of mining
Damage to ecosystems and animal habitats
Contamination of the environment
Expensive and unsightly
Disposal of waste materials
What order does the earths structure go?
It goes crust on the surface then mantle then outer core then inner core it gets hotter and hotter
