lecture 2 Flashcards
What is Plate Tectonics?
Also known as the theory of how the Earth works and ocean basins form, it describes the large-scale movement of seven large plates and many smaller ones on the earth’s lithosphere.
What are the rheological layers of the Earth?
Lithosphere (~0-100 km), Asthenosphere (~100-700 km), Mesosphere (~700-2885 km), Outer Core (~2885-5155 km), Inner Core (~5155-6370 km).
What are the compositional layers of the Earth?
Crust (oceanic: ~7 km, continental: ~35 km), Mantle (~7/35-2885 km), Core (~2885-6370 km).
What are P-waves and S-waves?
P-waves can travel through solids and liquids, reaching the outer core. S-waves cannot travel through liquids, hence do not pass through the core.
How do oceanic and continental crusts differ?
Oceanic crust is thin (~7 km), dense (ρ = 2.9 g/cm3), and young (<200 million years), while continental crust is thicker (~35 km), less dense (ρ = 2.6 g/cm3), and ranges from young to old (4.4 billion years to recent)
Where do tectonic plates move?
They move along the boundary between the lithosphere and asthenosphere, where rock is most plastic, not at the crust-mantle boundary.
What evidences support Plate Tectonics?
Distribution of fossils, similarity of rocks across continents, ancient glacial deposits, and the fit of the continents.
What are Mid-Ocean Ridges?
Seafloor mountains at shallow depths, where new crust is created as tectonic plates move apart.
What are Subduction Zones?
Seafloor trenches, the deepest parts of the ocean, where oceanic crust is destroyed as it sinks beneath another plate.
What are the three types of plate boundaries?
Divergent (plates move apart), Convergent (plates come together), Transform (plates slide past each other).
What hypotheses explain plate motion?
Ridge Push, Slab Pull, and Trench Suction, with convection currents in the mantle as a primary underlying force.
