Glossary of science Ch.4 2

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What is the thin and solid outermost layer of the earth above the mantle?
What is the layer of rock between the Earths's crust and core, contains most of Earths' mass?
What is the central part of the Earth?
What is a substance composed of 2 or more elements (chemically combined)
Why do less dense compoud make up the Earth's crust while the densest compounds make up the core?
because of the pull of gravity
What are the five main physical layers of the Earth?
-outer core
-inner core
What is the outermost, rigid layer of the Earth?
What is the 2nd layer that's solid rock that can flow, plates move on it, and is malleable?
What is the strong, lowest part of the mantle?
What is the liquid layer of the core?
outer core
What is the solid, dense center? (solid because of preasure)
inner core
What is the block of lithosphere that consists of the crust and rigid most outer layer of the mantle and moves around top of asthenosphere?
tectonic plate
What types of tectonic plates are there?
continental, oceanic, and a combo of both
What are some ways scientists know about the structure fo the Earths' interior?
-measure the speed of seismic waves
-travel times of seismographs
Who was Alfred Wegner?
scientist who proposed the hypothesis of the continental drift
(early 1900s)
What is the Continental Drift Hypothesis?
hypothesis that states continents once formed a single landmass, broke up, and driftedd to their present location
What evidence supports the Continental Drift Hypothesis?
-fossils of same organisms found of both sides of ocean
-similar rocks found on differnt continents
-coastlines roughly matche up
-mt. ranges would line up if land was back together
What was a single landmass when continents were joined?
-magma rises to surface and solidifies, fills gap between moving tectonic plates
-new crust forms
Sea Floor Spreading
What evidence supports the sea floor spreading hypothesis?
oldest crust farthest away from ridge
List 2 things that the reversed magnetism of the ocean floor tells us about the earth's history.
-all ocean floor was not formed at once
-earth's magnetic poles have reversed in the past
What is an underwater mountain chain that runs through Earth's ocean basins?
mid-ocean ridge
What occurs in the rift valley at the mid ocean ridge?
magma rises, lava hardens into new ocean floor
What is the theory that explains how large pieces of the Earth's outermost layer move and change shape on the asthenosphere?
plate tectonics
What are the 3 types of boundaries?
What boundary is it when plates collide?
What boundary is it when plates seperate?
What boundary is it when plates slide past each other?
What is believed to cause the motion of the tectonic plates?
-ridge push
-slab pull
What is it when higher ridge pushes lower oceanic lithosphere down?
ridge push
What is it when sinking plate edge is pulled by gravity and pulls on the rest of the plate?
slab pull
Explain how scientists use GPS to measure the rate of tectonic plate movement.
radio signals are continuously beamed from satellites to GPS ground stations
What is it when oceanic crust collides with continental crust, and the denser oceanic crust sinks into the asthenosphere?
What is it when the shape of rock changes cuz of stress?
(rock layers can bend and brake)
What is stress that occurs when an object is squeezed?
What is stress that occurs when forces stretch an object?
What happens when folding occurs with rock layers?
rock layers bend cuz of stress
What is the surface along wich rocks break and slide past each other?
What are the 3 types of faults?
-strike slip
What fault occurs when plates are pulled apart?
What fault occurs cuz of compression?
What fault occurs when opposing forces break rock and move horizontally?
strike slip
What forms from collisions at convergent boundaries, can form highest mts. in world, and is the most common?
folded mountains
What forms when tension at normal fault cause large blocks of crust to drop down relative to others? (sharp, jagged rocks)
fault block mountains
What usually forms at a convergent boundary where suduction occurs?
volcanic mountains

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