Chapter 4 Earth & the Environment Flashcards
What 2 primary sources of energy drive our “Earth System?”
- Solar radiation emitted from the sun.
- Heat contained within our planet
Rocks undergo deformation when acted upon some type of outside _____________
Force or Stress
Strain usually involves some change in____________ or _________________.
Shape or volume
What is the point where rocks will no longer behave elastically and deformation becomes permanent?
Elastic Limit
Brittle
When rocks break by fracturing (upper crust)
Ductile
When rocks deform by flowing and folding (lower crust and upper mantle)
What is the difference in stress and strain in rock deformation?
Stress is caused by a force acting on a rock.
Strain is the result of deformation.
What are 3 types of stress?
- Compression
2.Tension
3.Shear
What force occurs when an object is squeezed?
Compression
What force occurs when an object is pulled apart?
Tension
What force develops when surfaces slide past one another?
Shear
What are earth’s 3 compositional layers and how thick are they?
- Crust: 5-75 km thick
- Mantle: extends from base of crust to ~2900 km depth
- Core: extends from base of mantle to 6371 km depth
What is earth’s crust mostly contain?
Light silicate-rich rocks
Oceanic crust is thinner and dense than _________________ crust.
continental
The mantle made up mostly of what?
Ultramafic silicate-rich rocks
The earth’s core is composed almost entirely of __________________.
Iron
What are earth’s 5 mechanical layers?
- Lithosphere
- Athenosphere
- Mesosphere
- Outer Core
- Inner Core
Which mechanical layer of Earth is the outmost rigid layer that is composed of crust + uppermost mantle?
Lithosphere
Which mechanical layer of Earth extends from base of lithosphere to ~660km depth?
Athenosphere
Does the athenosphere behave as a soft solid or rigid?
Soft solid
Is the athenosphere ductile or brittle deformation?
Ductile
The rigid mesosphere is the remainder of the :
A. Crust
B. Mantle
C. Dr. K’s shoes
B.. Mantle
Which mechanical layer of earth is liquid iron that is flowing?
Outer Core
The inner core of the earth is solid _____________.
Iron
In Wegener’s theory of Continental Drift, he hypothesized Pangaea. What is Pangaea?
A supercontinent. All the continents were together, as in one big continent.
What is the theory that land masses slowly drift?
Theory of Continental Drift
What are 5 observations Wegener made in the Theory of Continental Drift?
- Continents appear to have fit together in the past.
- Evidence of glaciers found on 5 continents.
- Interpreted ancient environments in wrong present day places
- Identical fossils found on widely separate land masses.
- Distinctive rock assemblages and mountain belts match across the Atlantic
Even though Wegener had strong lines of evidence, why was his ideas ignored?
He could not explain why or how continents moved.
What is a submarine mountain range in found in all oceans?
Mid-ocean ridge
Deep, narrow depressions that parallel coastlines and are found where you also find volcanoes
Ocean trenches
4 observations of sea floor spreading
- Sediment thickens away from ridges
- Earthquakes at MOR indicate cracking
- New ocean floor forming at MOR
- Earthquakes at trenches indicate collisions and bending
What are individual slabs of the brittle lithosphere that move over the relatively weak asthenosphere?
Plate Tectonics
What are the 3 types of plate boundaries?
1.Divergent
2. Convergent
3. Transform
Name that plate boundary!
1. Plates move apart: tensions stress
2. Significant volcanism and many small earthquakes
3. New lithosphere is created at these boundaries
Divergent plate boundary
What kind of divergent boundary is defined by:
1. oceanic plates moving apart at MOR
2. rising asthenoshpere melts, forming mafic magma
3. Magma solidifies into new oceanic crust
Oceanic Divergent Boundary
Name 3 things that happens at Convergent Plate Boundaries.
- compressional forces
- Subduction
- Earths greatest earthquakes
To have subduction, one plate MUST be_______________.
Oceanic crust
3 types of convergent boundaries:
- Ocean-ocean convergence
- Ocean-continent convergence
- Continent-continent convergence
Plate Boundary where tectonic plates slide past each other: shear stresses
Transform Plate Boundary
Plume of deep mantle material independent of plates
Hotspots
There are 2 primary forces that drive plate motions (Driving mechanisms). What are they?
- Ridge-push
- Slab-pull
Both driving mechanism forces, ridge-push and slab-pull, are driven by ____________________ in the upper mantle.
convection
