geography rocks and wheathering Flashcards
what exactly is rock?
Rock is a mixture of minerals.
what is a mineral
A mineral is a natural compound. It has a chemical name and a formula, like the compounds in science – but we use its geological name.
what is geology
Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them.
describe sedimentary rocks
colourful
rough texture
forms in layers
reacts to weathering and erosion
describe igneous rocks
resistant to erosion and weather
hard
shines when polished
describe Metamorphic rocks
soft texture
resistant to weather
hard wearing
examples of sedimentary rock
sandstone chalk
limestone
shale
examples of igneous rock
obsidian volcanic ash
basalt granite
examples of metamorphic rock
marble schist
slate
how are sedimentary rocks formed
Sedimentary rocks are formed from sediments that have settled at the bottom of a lake, sea or ocean, and have been compressed over millions of years.
how are metamorphic rocks formed
Metamorphic rocks have been subjected to tremendous heat and/or pressure, causing them to change into another type of rock
how are igneous rocks formed
Igneous rocks are formed by magma cooling from the molten interior of the Earth.
extrusive igneous rock
form from lava cooling at the surface of the Earth.
intrusive igneous rock
form from magma cooling underground, often relatively deep in the Earth.
weathering
Weathering is the breaking down of a rock by the action of things in its environment e.g. heat, cold, rain, plants, chemicals etc.
erosion
Erosion is the wearing away and removal of rock stone and soil by rivers waves wind and glaciers
Physical weathering
caused by the effects of changing temperature on rocks, causing the rock to break apart.
Freeze-thaw weathering (physical)
occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart.
Exfoliation weathering (physical)
occurs as cracks develop parallel to the land surface a consequence of the reduction in pressure during uplift and erosion.
Solution weathering (chemical)
removal of rock in solution by acidic rainwater. In particular, limestone is weathered by rainwater containing dissolved CO2, (this process is sometimes called carbonation)
chemical weathering
caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic.
Hydrolysis weathering (chemical)
the breakdown of rock by acidic water to produce clay and soluble salts.
oxidation weathering (chemical)
the breakdown of rock by oxygen and water, often giving iron-rich rocks a rusty-coloured weathered surface.
Biological Weathering
Living organisms contribute to the weathering process
