Earth Structure Flashcards
(24 cards)
Do we have any direct observation of the interior structure of the Earth?
No
How to we know what is below the Earth’s crust?
Indirect observations
What are 2 kinds of indirect observations we use to study the interior structure of the Earth?
Seismic Waves
Discontinuities
Describe Seismic Waves
How we measure earthquakes
Surface waves: travel across whole earth
Body waves: travel through earth
What are discontinuities?
Boundaries between layers
List the compositional layers of the Earth’s interior according to density
Crust = least dense Mantle = more dense Core = highest density
What are the final layers and character of the Crust?
Crust=
Crust - Solid
Uppermost Mantle - Solid
What are the final layers and character of the Mantle?
Mantle=
Asthenosphere - Plastic
Upper Mantle - Solid
Lower Mantle - Solid
What are the final layers and character of the Core?
Core=
Outer Core - Liquid
Inner Core - Solid
What is a plastic?
A malleable solid (changes shape when pressure is applied)
What is Moho Discontinuity (ie Mohorovicic)?
In the Lithosphere, the boundary between the crust and the uppermost mantle
Where is the Lithosphere?
The Lithosphere sits on the asthenosphere, floating along
What are the 2 types of crust and how do they differ?
Oceanic- thinner and denser (floats lower)
Continental- less dense and thicker (floats higher)
What is Isostatic Adjustment?
When the crust thickens, gets heavier and sinks (mountain building) or when the crust thins, gets lighter and floats (mountain wears away) -made possible by the plasticity of the Asthenosphere, causing Lithosphere to get pushed down and rise back up as weight changes on top
What is a Geological Process/Cycle?
The set of processes that lead to changes in characteristics of the earth/changes the surface of the earth
What are the 2 Geological Processes?
Exogenous and Endogenous
Describe Exogenous
Process occurring outside the earth
Describe Endogenous
Process occurring from within the earth
How old is the Earth?
4.6 billion years old = “Incomprehensible”
What are the 2 ways to measure time?
Absolute and Relative
What is Absolute Time?
How long something has been in existence (ie Radiometric dating)
What is Relative Time?
How old something is in relation to something else (ie Superposition, Relative dating)
What is Uniformatism?
The same physical processes active in the environment today have been operating throughout geologic time. The slow application of a process making small changes over long periods of time.
What is Catastrophism?
Sudden, large changes in a short period of time (pertains to more non-scientific understandings of the world)
