CH 14 Plate Tectonics
_____ are formed when two continental plate collide.
Mountains
the ____ is an example of a transform boundary.
San Andreas Fault
The East African Rift is an example of a ?
continental rift
what kind of currents inside Earth might drive plate motion?
convection
The arrows in the mantle and oceanic crust indicate the direction of flow of _____ beneath the plates.
convection currents
The Himalayan mountain range of India was formed at a ____
convergent boundary
Active volcanos are most likely to form at ________.
convergent oceanic-continental boundaries
scientists believe that differences in ____ cause hot, plastic-like rock in the asthenosphere to rise toward Earth's surface.
density
the circulation of material caused by differences in _____ is called convection.
density
What type of plate boundary occurs between the North America Plate and the Eurasian Plate?
divergent
What new technology was used to map the seafloor beginning in the 1940s and 50s?
echo sounding
What was the same on several continents that supports the hypothesis of continental drift?
fossils and rocks
Name a fossil plant that helps support the theory of continental drift is ______
glossopteris
the crust and upper mantle make up Earth's ____
lithosphere
the alignment of iron minerals in rocks when they are formed reflects the fact that Earth's _____ has reversed itself several times in the past.
magnetic field
the driving forces of tectonic plates are related to convection currents in Earth's ....
mantle
A vast, underwater mountain chain is called a ?
mid ocean ridge
the youngest rocks on the ocean floor are located where?
mid-ocean ridges
The magnetic pattern of ocean-floor rocks on one side of an ocean ridge is ____ of that of the other side
mirror-image
seafloor spreading occurs because ?
molten material beneath Earth's crust rises to the surface
A lack of explanation for continental drift prevented many scientists from accepting that a single supercontinent called ____ once existed.
pangea
The result of plate movement can be seen at ____.
plate boundaries
In what direction does warmer material move in convection current?
rises
In order to complete a convection current, the rising material must eventually ____ Earth.
sink back into
Crust is neither destroyed nor formed along which of the following boundaries?
transform
plates slide past each other
transform boundary
How does a subduction zone form?
when oceanic plate and continental plate collide, the more dense oceanic plate slips under the continental plate edge.
Scientists have observed that the continents move apart or come together at speeds of a few centimeters per ?
year
convergent
2 plates collide
divergent
2 plates divide
transform
2 plates slide past each other
Wegener believed that the continents were assembled as part of a supercontinent about how many years ago?
250 million
Explain how the Andes mountain range formed.
At a convergent boundary between an ocean plate colliding to a continental plate.
Know what the Theory of Plate Tectonics is about.
Earths surface is made at rigid rock plates that move with respect to each other
Continental drift was not widely accepted when it was first proposed. Why?
Wegener could not explain why or how the plates moved.
Plates of the lithosphere float on the ____.
asthenosphere
