Chapter 2 Flashcards
discovered outer core was liquid
Inge Lehmann
How did Inge Lehmann discover the outer core was liquid?
Through Seismic Waves
Created theory of continental Drift; Meterologist
Alfred Wegener
Super continent that indicted that the land masses drifted apart
Pangaea
How Wegener “supported” his theory on Continental Drift
Fossil Evidence
Matching Geologic Units
Glacial Evidence
How fossil evidence support continental drift?
Different land mammals and plants were on differing continents separated by oceans
How matching geologic units supported continental drift?
There were distinctive rock assemblages with mountain ranges and rock types fitting together (when realligned)
How glacial evidence supported continental drift?
Glaciers left marks on lands and rocks that are now oceans apart
Key features of the ocean floor
Mid ocean ridges
Deep Trenches
Sea Mountains forming Alignments
How was the ocean floor discover to NOT be smooth?
Sonar from submarines (WW2)
Where is heat flow greater?
at a mid ocean ridge
first plotted that the ocean floor was not flat
marie tharp
Creates brand new crust, causes continents to move apart
Sea floor spreading
How can you tell how fast sea floor spreading is taking place?
How thick/thin the rock is
in terms of SFS, thin =
Slow
in terms of SFS, thick =
Fast
Type of plate boundaries
Divergent
Convergent
Transform
“theory” that the continents fit together accordingly
jigsaw piece
separate area of land and shallow seas from the deep ocean basins; mark edge of continents
continental slopes
Confirms jigsaw theory by showing these pieces of earth align perfectly
Under water mountain ranges (ancient mountain belts)
crustal fractures (also help prove jigsaw theory)
faults
Part of Pangaea, assembly of the southern; Assembly of the southern continents
Gondwana
What evidence indicates Gondwana?
Glaciation and coal formation suggests the continents were close to south pole. Glacier movement goes out ward indicating a center point towards antartica
Why was continental drift rejected?
No viable mechanism to explain continental drift
flight away from the poles; flight moved through gravity of equatorial bridge; theory
Polflucht
study and measurement of earth’s Magnetic field from ancient rocks
Paleomagnetism
Where does earth’s magnetism come from?
Outer Core
What two parts does a compass have?
Horizontal component (swing) & vertical component (tilt)
How basalt rock becomes magnetic?
Cools then forms iron oxide
measures basalt rock magnetic orientation
magmetometer
curve showing magnetic poles moving overtime due to basalt rocks having different magnetic orientations
Polar wander
continents drifted based on center point of magnetic field and independently
apparent polar wander
Earth’s magnetic field periodically reverses itself
Magnetic polarity reversal
North end of compass points toward the S geographic pole
Reverse magnetic polarity
who created Seas Floor Spreading?
Lawrence Morley, fred vines, drummond matthews
Theory/hypothesis that the seafloor moves symmetrical away from major ridges, moving ocean and continents with it
Sea floor spreading
True name given to sea floor spreading
“Vine-Matthews-Morley” Hypothesis
What did Sea Floor spreading enhance>
Wegener’s theory (provided mechanism)
Areas in the ocean where lava comes out of the top and assist SFS
Mid Ocean Ridges
strip like patterns that indicate the magnetic patterns
Magnetic Anomalies
Where is young crust located
Mid Ocean ridge Peak
Where is older crust located
Away from Mid ocean Ridge
How was the age of SFS tested?
Drilling ship (glomar challenger)
Oceanic crust was found to lurch violently back into earth’s heated core; ocean floor is consumed
subduction
Place where old crust goes for subduction; mainly located in Pacific Ocean
Deep ocean trenches
generated along upper boundary of the subducting slab of Ocean
subduction zone
line of volcanoes bordering the trenches that encircle the pacific
Pacific ring of fire
Resulting line of volcanic islands that are curved and parallel to the adjacent ocean floor
Island arc
