Module 2 Flashcards
Geoligical cycle is made up of a group of 4 sub-cycles
Tectonic cycle
rock cycle
hydrological cycle
biogeochemical cycle
Rock Cycle
.
Rock Cycle
.refers to the worldwide recycling of three major groups of rocks, driven by earths internal heat and by energy from the sun
- depends on tectonic cycle for heat and energy
- biogeochemical cycle for materials
- hydrological cycle for water which plays an essential role in weathering, erosion, transportation, deposition, and lithification
- the rock cycle refers to the continuous transformation of 3 classes of rocks: igneous, sedimentary and metamorphic
rocks are..
aggregates of one or more minerals
-minerals are naturally occuring crystalline substance with a specific elemental coposition and a narrow range of physical properties
3 types of rock, describe rock cycle like on diagram
- igenous rock-formed by the crystalization of molten rock beneath and on earths surface
- Sedimentary rock-sediment is converted to sedimentary rock by lithification which takes place by compaction and cementation of sediment during burial
- Metamorphic rock- may be buried to depths where pressure and temp coonditions cause them to melt, beginning the entire rock cycle again
1.Magma becomes lava and cools becoming extrusive igneous rock
2.Exogenic(from outside earth) sun energy weathering, erosion, and transportation
-causes lithification transforming sediments into sedimentary rock
3. Generally at rock boundaries, high pressure transforms sedimentary to metamorphic rocks
-igneous can also become metamorphic rock
4. Fate of all rocks to be deeply buried and returned to plasticity and eventually magma to enclose rock cycle
.weathering and erosion effects all steps
Hydrological Cycle
the cycling of water from the oceans to the atmosphere, to continents and islands, and back again to the oceans
-driven by solar energy and operates by way of evaporation, precipitation, surface runoff, and subsurface flow
Biogeochemical Cycle
is the transfer or cyclingof an element(s) through the atmosphere, lithosphere, hydrosphere, and biosphere
- photosynthesis and respiration
- remember that some portions of rock and soil have important portions which are organically sourced like carbon
_______, _______, and ______influence the type, location, and intensity of earth processes
geology, topography and climate
Tectonic Cycle
tectonic activity refers to large-scale earth processes that cause the movement and deformation of Earth’s lithospheric plates
these processes create landforms and landscapes at a variety of spatial scales (e.g., orogenic mountain ranges and ocean basins to individual faults).
tectonic processes are driven by energy generated deep within Earth: original heat of formation of the planet, heat generated by crystallization of the core, and heat supplied by radioactive decay of elements in the mantle – endogenic processes
endogenic processes vs. Exogenic proccesses
energy generated deep within Earth: original heat of formation of the planet, heat generated by crystallization of the core, and heat supplied by radioactive decay of elements in the mantle
-endogenic processes (e.g., melting rocks to form magma)
exogenic processes driven by energy from Sun (e.g., weathering)
__% of water is in the oceans
97
Internal Structure of earth is based on..4 things
chemical composition of rock;
physical state – solid vs. liquid;
density;
rock strength
Describe internal structure of earth(4)
1.Solid inner core
-6000 to 5000 km down
> 1300 km thick
-extremely hot temperatures
-primarily metallic; consists mostly of iron (Fe) with minor amounts of nickel (Ni), sulphur (S), and oxygen (O)
-average density – 10,700 kg m-3
- Liquid outer core
- 5000 to 3000 km down
- over 2000 km thick
- composition and density similar to inner core
- movement within the outer core generates Earth’s magnetic field
3.Solid mantle
~3000 km thick
-composed largely of iron (Fe) and magnesium (Mg)-rich silicate minerals – ferromagnesian minerals
-average density – 4,500 kg m-3
- Solid crust
- thickness ranges from 6-7 km beneath ocean basins to ~70 km beneath mountain ranges of continents
- continental crust composed largely of silicate minerals rich in aluminum (Al) – aluminosilicate minerals
- average density of continental crust – 2800 kg m-3
- composition of oceanic crust similar to underlying mantle
- average density of oceanic crust – 2900 kg m-3
Average densities of:
Continental Crust=
Oceanic Crust=
Mantle=
Core=
- 8 g/cm3
- 9
- 5
- 7
(oceanic lithosphere is composed of these)
continental lithosphere is composed of these
.Solid Mantle: ferromagnesian minerals.
Solid Crust: aluminosilicate minerals
lithosphere
cool, strong outermost layer of Earth is termed the lithosphere – crust + rigid uppermost portion of mantle
-lithosphere varies in thickness: few km beneath mid-oceanic ridges; ~120 km beneath ocean basins; 20-400 km beneath continents
Aesthenosphere
a mass of hot, relatively weak rocks (i.e., magma) capable of slow movement
- lies just underneath lithosphere
- .capable of flowing
- .movement of material in this level is the cause of movement of plate tectonics
_______ apparently operates to move materials within the mantle;
convection apparently operates to move materials within the mantle; convection is driven by heat from Earth’s core
-convection is driven by heat from Earth’s core
Plate Tectonics
.processes involved in the creation, movement, deformation and destruction of plates
lithosphere is broken into larger and smaller pieces called lithospheric plates
plates may include a continent and parts of ocean basins, or may be restricted to only ocean basins
plates move relative to one another at rates of several cm per year
Alfred Wegener
historic development of plate tectonic theory:
.continental drift - Alfred Wegener (1912)
-coastline fit – Southern Hemisphere continents
-similarities in Paleozoic geology and palaeontology
-single continental landmass – Gondwanaland
theory lacked a convincing mechanism capable of moving continents across surface of Earth
-sea floor spreading eventually became accepted mechanism
Mid-oceanic ridges
subduction zones
oceanic trenches
Mid-oceanic ridges= plates are diverging(moving away from eachother)
Subduction zones(convergence)= where plates collide and one plate is driven upwards by the other
oceanic trenches(subduction)-oceanic plates subducted because of higher density
Transform Plate Boundaries (located on western N.A coastline): name of fault there
San Andreas Fault