Development of Tectonic Theory Flashcards
What was a major development that contributed to the theory of plate tectonics?
the field of paleomagnetism
paleomagnetism is the study of _____ magnetism
rock
_________ is the study of rock magnetism
paleomagnetism
as magma solidifies and cools ____ bearing minerals actually align to earths ______ field
iron, magnetic
paleomagnetism allows us to tell when the Earth’s ______ have switched
poles
by mapping _____ on the ocean floor geologists started to get weird results that showed that the Earth’s _____ pole over the past 100 million years seemed to be migrating along the side of the Earth.
rocks, magnetic
continents and rocks themselves were moving ____ to the magnetic pole.
relative
what explained how the continents were moving?
sea floor spreading
what was the conclusion for the supposed movement of the poles?
the poles were stationary and the continents moved
There was overwhelming circumstantial evidence for continental drift, but no direct clues until ______ mapped the ages of ______ rocks
oceanographers, seafloor
What was the mechanism for plate motion?
sea floor spreading
When the ages of seafloor rocks were mapped using _____ ______ records, what did scientists find?
- pole reversal records.
– Mid-sea ridges made of youngest rocks
– Older rocks symmetrically situated on either side
Mid-sea ridges made of the ______ rocks
youngest
sea floor spreading happens when…
the sea floor splits apart at mid-ocean ridges
where does sea floor spreading happen?
at mid-ocean ridges
How does the sea floor spread? What are the four components of the spreading process?
- Magma swells up and is extruded
- Solidifying magma records the direction of the Earth’s magnetic field
- Rock spreads out in a continuous spill
- Older rock “pushed” away from the ridge and younger rock takes its place
In the Plate tectonic model the lithosphere floats on top of the _________
asthenosphere
