Plate tectonics Flashcards
(16 cards)
Wegner
Theorized drift of continents
Called supercontinent Pangea
Evidence Wegner used to propose idea of continental drift and why his idea was not immediately accepted
?fossils found opposite sides of oceans
Mechanism of continental drift (plate tectonics)
?seafloor spreading
How nature of science illustrated by development of knowledge of theory of plate tectonics
? It wasn’t believed, wegners beliefs until more evidence and technology present
Crustal plates
?Crustal plates form the outer layer of the Earth. There are 12 major plates and many smaller plates. These tectonic plates are formed from the Earth’s crust and uppermost part of the mantle.
Pangaea
?wegners proposed supercontinent
Evidence for continental drift and sea floor spreading (relationship to Lab activity with poster board with slot)
?fossil evidence, distribution of present day organisms, evidence of ancient climates different than climates in current locations.
Rift (land and sea)
rift valley is a lowland region that forms where Earth’s tectonic plates move apart, or rift. Rift valleys are found both on land and at the bottom of the ocean, where they are created by the process of seafloor spreading.
Two places where you can see rifts on land
?
Types of Crustal plate boundaries (Graham cracker activity)
Divergent – plates move apart,”rifts” , New crust is formed. Underwater (seafloor spreading, mid ocean ridges) Atlantic Ocean, Indian Ocean, Red Sea, gulf of California. Land-East African rift, Iceland
Convergent- subduction zones, as in Clay activity in stories in stone more dense crust slide under less dense crust . Deep ocean trenches, deep focus earthquake , volcanic activity, Mountain chains formed
Transform- plates grind past each other without production of new crust or destruction of existing crust. Example San Andreas Fault
Relationship of plate boundaries to earthquake and volcano locations
?Convergent
Subduction formation of Hawaii
?In areas where the plates come together, sometimes volcanoes will form. Volcanoes can also form in the middle of a plate, where magma rises upward until it erupts on the sea floor, at what is called a “hot spot.” The Hawaiian Islands were formed by such a hot spot occurring in the middle of the Pacific Plate.
Midway Island chain
?While most volcanoes are created by geological activity at tectonic plate boundaries, the Hawaii hotspot is located far from plate boundaries. … According to this theory, the nearly 60° bend where the Emperor and Hawaiian segments of the chain meet was caused by a sudden shift in the movement of the Pacific Plate.
Emperor seamounts
?Hawaiian seamount Chainthat stretches from the Hawaiian islands to the aleutian trench form other volcanic hotspots in association with mantle plumes
Cause of plate tectonics
?The lithosphere which is broken into segments commonly referred to as plates overlies a week region in the mantle known as the asthenosphere. The temperatures and pressures in the upper asthenosphere are such that the rocks there are very near they’re melting temperatures and respond to stress by flowing as a result earth rigid outer shell is effectively detached from the layers below which permits it to move independently
Hot spots
A concentration of heat in the mantle capable of producing magma, which in turn extrudes onto earth surface. The intraplate volcanism that produced the Hawaiian islands is one example
