Fundamentals of Geology (F4 Key Idea 2) Flashcards
What is some evidence for continental drift?
• Coastline shapes complimenting eachother
• Same fossils in different continents
• Same mountain belts in different continents (same mountain, different countries)
What is continental drift?
the proposal that the continents have changed their relative positions over time
What is Gondwanaland?
Ancient super-continent that incorporated present-day S.America, Africa,India,Australia and more
What is evidence of plate tectonics?
• Geology - sedimentary/igneous rocks from Scotland match those found in Newfoundland
• Ancient shield mountains can be traced from east Brazil to West Africa
• Fossils
What is a divergent plate margin?
Plates moving apart
What is a convergent plate margin?
Cont.-Cont. - neither subduct, fold mtn forms
Cont.-Oceanic - oceanic subducts
Oceanic-Oceanic - older & colder plate subducts into mantle
What is a conservative plate margin
Plates moving past eachother
What is a Ridge Push?
• Mantle upwells (a process in which deep,cold water rises towards surface) at plate boundary
• Sea floor at MOR gets significantly raised
What is Slab Pull?
The mass of cold, dense oceanic plate sinks at the subduction zone
This pulls the rest of the Oceanic plate with it
Is Oceanic or Continental crust older?
Continental
4.0billion years old vs Oceanic being <200million years old
What is Paleomagnetism?
the Earth’s magnetic field preserved in rocks
Mafic rocks contain a record of the direction and inclination of the Earth’s magnetic field at the time of their formation
• Can be used to determine changes of latitude as continents move with time.
• Ocean floor anomalies (magnetic stripes) indicate sea floor spreading and rates.
What is igneous rock?
• Forms from magma or lava solidification
• Hard, no layers
Can be:
• Intrusive (slow magma cooling)
eg granite
• Extrusive (rapid lava cooling)
eg obsidian
What is Sedimentary rock?
• Forms from sediment compaction
• Crumbly, layered
Can be:
• Clastic (compacted broken rocks)
eg sandstone
• Chemical (compacted dissolved material)
eg limestone
• Organic (compacted biogenic matter) eg coal
What is Metamorphic rock?
• Forms by transformation of other rocks
• Relatively hard, may or may not have hard layers
Can be:
• Foliated (has layers)
eg slate
• Non-foliated (no layers)
eg marble
What is the collision of plates forming a mountain range known as?
Orogeny
