Material c Flashcards
The surface of the earth is the interface between:
land air and sea
three major components of the earth
Crust, Mantle, Core
Lithosphere (3)
-crust and uppermost solid mantle
- 0 to 100km
- surface of the earth divided into a series of rigid plates which move
Crust (4)
- formed between 3.9 and 4.5 x 10^9 years ago
- Represents <1% of the earth’s total mass
- the thickness varies between 5 - 35 km thick depending on region (continent or ocean)
- crust is continually being built and eroded
endogenic
land forming process with origin underground
exogenic
weathering and erosion surface process
Asthenosphere (3)
-soft region of upper mantle, below lithosphere
-100 to 300 km
- soft and deforms
Plate boundaries (3)
- transform boundary
- divergent boundary
- convergent boundary
Transform boundary
two plates moving side to side (one past the other), without colliding or moving apart
divergent boundary (2)
- plates moving apart without colliding
- occur in mid ocean, leading to new crustal material from below.
Convergent boundary (7)
-when two plates move toward each other
Two types:
- If one plate in continental and the other is oceanic:
- subduction occurs, eg oceanic plate moves below continental plate
- this cause melting of subduction plate.
- results in mountains, volcanoes, as less dense molten material rises.
- If both plates are continental:
-plate thickening occurs with no significant subduction, eg; himalayas.
Crust composition, rocks (5)
- nonliving material that forms the crust (eg. sand and clay)
- most rocks are composed of minerals
- over 2000 minerals exist, there are 10 major mineral groups that the minerals belong to.
- minerals are called silicates, if they contain oxygen and silicon
- minerals are called alumiosilicates, if structure contains oxygen, silicon and alumium
crust composition, major rock-forming minerals average abundance (4)
-limestone: 92.8% carbonates.
-sandstone: 69.8% quartz.
-basalt: 46.2% feldspars and 36.9% pyroxenes.
-granite: 52.3% feldspars 31.3% quartz
major chemical elements of earth’s crust (8)
- oxygen 47% (most abundant)
- silicon 28%
- aluminium 8%
- iron 5%
- calcium 4%
- potassium 3%
- sodium 3%
- magnesium 2%
rock types
- igneous, sedimentary, metamorphic
Igneous rocks (5)
-formed by the cooling (solidification) of molten rock (magma).
- extrusive: (volcanic) rocks formed from molten rock (lava), at earth’s surface.
- fast cooling, little crystal formation, and forms fine grained rocks. eg basalt.
- Intrusive: (plutonic) rocks formed from molten rock (magma) beneath earth’s surface.
- slow cooling, large crystal formation, and forms course grained rocks. eg granite.
Sedimentary rocks (5)
-formed as the result of moderate pressure on accumulated sediments.
-sediments result from:
-weathering and erosion (lead to clastic rocks)
-dissolved materials precipitation (lead to non-clastic rocks) eg gypsum, limestone (evaporite group)
-biological activity (lead to non-clastic rocks) eg peat and coal.
Metamorphic rocks (6)
- formed by exposing parent rocks (sedimentary and igneous) to extreme heat, pressure, and/or permeating hot gasses or liquids (processes occur deep below earth’s surface).
- Extreme heat “thermal metamorphism”: results in rocks with new minerals, as temp. causes parent rock to melt and re-crystallize.
- Pressure and heat: will favor formation of denser minerals over less denser ones in rocks
- same mineralogical composition - Permeating hot gases or liquids “metasomatic metamorphism”: changes rock’s mineralogical composition.
- as gasses or liquids act as export/transport for minerals.
categorizing metamorphism (3)
- contact metamorphism
- regional metamorphism
- dislocated metamorphism
contact metamorphism (3)
- occurs as a result of magma intrusion
- occurs over small areas
- leads to marble for example
Regional metamorphism (3)
- occurs over large areas (of mobile belts)
- leads to rocks eg; gneiss and schist
- occurs with large geological processes such as mountain building.
Dislocated metamorphism (3)
- occurs in vicinity of earth movements.
- involved with large geologic process, such as mountain building, but dominated by pressure.
- referred to as dynamic, clastic and mechanical metamorphism.
rock cycle (9)
(1) Magma flow from the mantle to earth’s surface (lead to volcanic eruptions and extrusive igneous rocks) (2) or to intrusive igneous rocks (3) which are either brought up to surface by uplift and erosion, (4) or go through burial, heating and deformation to become metamorphic rocks. (5) weathering and erosion by volcanic eruptions moves material to sea and by transport and deposition enter the crust leading to sedimentary rocks, (6) which can be brought up to the surface by uplift and erosion (7) or undergo a process of burial, heating and deformation leading to metamorphic rocks (8) which are either brought to surface through uplift and erosion or (9) join magma flow from mantle through fusion at depth.
rock weathering
can be physical, chemical or biological.