Rocks And Fossils Flashcards
(43 cards)
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
