What are the two types of processes that constantly shape the Earth’s structure?
endogenous - occur within the earth: driven by energy from the interior (ex. volcano, plate tectonics)
exogenous - occur on or near the surface: driven by external sources, mainly the sun (ex. weathering, erosion)
Explain the Earth’s dymanics driver: heat
- solar energy ex
- primordial heat: heat
from the formation of earth int - radiogenic heat: heat from decay of radioactive elements, mainly K, Th, U int
Internal heat controls
- movement of material in
the Earth - plate tectonics
- magmatism
- metamorphism
Solar heat controls
- climate and weather systems
- ocean circulation and winds
- Exogenous geological processes like weathering, erosion, evaporation
- biological activity
Explain the Earth’s dymanics driver: gravity
- controls layered structure of planet based on density (dense materials sink, light rise)
- exogenous geological
processes like erosion and
transport
Explain the Earth’s dymanics driver: rotation
- affects atmosphere
and ocean currents - affects outer core
What are the three main chemical (compositional) layers in the Earth?
- crust
* 5 – 70 km thick
* sillicate (basaltic - granitic) composition - mantle
* sillicate (peridotitic) composition - core
* Fe-Ni alloy
What is the mantle–crust boundary called, and how deep is it?
mohorovičić discontinuity (Moho), about 5–70 km deep
What is the core–mantle boundary called, and how deep is it?
gutenberg discontinuity, about 2900 km deep
What is the total radius (depth to the center) of the Earth?
approximately 6378 km.
setri se osle :P
What is direct sampling?
- in da crust
- fieldwork, mining, drilling
What is indirect sampling?
- in da mantle
- xenoliths (fragments of mantle brought up by magma)
- ophiolites (fragments of former oceanic lithosphere exposed on land)
Reflect mechanical (rheological)
behavior of the lithosphere.
- rigid
- crust + uppermost mantle
Reflect mechanical (rheological)
behavior of the asthenosphere.
- plastic (very viscous liquid)
- upper mantle
Reflect mechanical (rheological)
behavior of the mesosphere.
- more rigid than asthenosphere
- lower mantle
Reflect mechanical (rheological)
behavior of the outer core.
- liquid
Reflect mechanical (rheological)
behavior of the inner core.
- rigid
What are seismic waves?
- they develop due to earthquakes
- travel at speeds that depend on elastic
properties (rigidity, plasticity,density, solid vs. liquid) - travel through different materials (solid vs liquoid)
What is mantle tomography?
a method of creating a 3D map of the mantle using seismic waves from distant earthquakes
What is the magnetic field?
- we observe magnetic field on the surface (compass)
- the magnetic poles roughly align with geographical poles
- magnetic poles move, (polar wander)
- liquid outer core composed of iron and nickel creates electrical currents which generate magnetic field = called geodynamo
What is gravimetry?
- study of Earth gravity
- Denser rocks create high gravity anomaly
What is heat flow?
- study of earth’s heat
- different areas have different
geothermal gradient
What are the different Earth systems that interact through the flow of matter and energy?
- geosphere - rocks, minerals, what shapes them
- hydrosphere - all water within/on/above earth’s surface (Oceans, seas, rivers, lakes, glaciers, groundwater, atmospheric water vapor)
- cryosphere - all frozen water, glaciers, ice caps, ice sheets, permafrost, sea ice
- atmosphere - gaseous envelope surrounding earth
- biosphere - all living things
- other minor spheres
