The density of the material inside Earth _________ with increasing depth
The outermost part of Earth that moves rigidly and comprises what we call the plates is the _______
Changes in magnetic polarity of the sea floor create a pattern of ________ parallel to ridges.
The oceanic crust is subducted into the ______ at oceanic ________
Fixed sources of heat deep in the mantle that burn holes through the overlying crust and reveal the direction of motion of the plates are called _______.
The theory that addressed the apparent ability of landmasses to move through the crust is called ________
The theory that described the creation, destruction, and mobility of the oceanic crust is called ________
SEA FLOOR SPREADING.
The broad theory that describes the dynamic nature of large segments of the lithosphere and the underlying mantle is called ______
New oceanic crust is created at _______ plate boundaries.
The edge of a continent that is closest to a trench is called the ______ margin.
Scientists today would characterize the Earth as being composed of spherical ________
The _________ is solid, very dense, very hot, and rich in iron and nickel.
The largest layer of Earth is called the ______
A _________ is an Earth shock wave or vibration produced by an earthquake or underground explosion.
When seismic waves encounter layers of different ________ they bend or _________
The _______ of seismic waves changes from layer to layer.
Continental landmasses (crust) are formed primarily of ______ while oceanic crust is primarily made up of _______.
The _______ is the area of the upper mantle just below the lithosphere that behaves in a plastic fashion.
The _______ of a portion of a lithospheric plate determines its final elevation.
Our current models of the interior of Earth are based on
a. observations of earthquake waves. b. examination of meteorites. c. measurements of gravity. d. the shape of Earth. e. all of the above. (Answer)
The largest internal subdivision of Earth is the
a. crust. b. mantle. (Answer) c. outer core. d. inner core. e. lithosphere.
Mantle convection cells
a. rise beneath ocean trenches. b. bring granite to the surface to form continents. c. carry mantle material upwards beneath ridges. (Answer) d. inhibit the motion of the plates. e. only occur beneath continents.
a. cools as it moves away from ridges. b. thickens away from ridges. c. increases in age towards ridges. d. a and b above. (Answer)
The oldest oceanic crust is roughly
a. 2 million years old. b. 20 million years old. c. 200 million years old. (answer) d. 2 billion years old. e. none of the above.
Old oceanic lithosphere is destroyed at
a. convergent plate boundaries. (Answer) b. divergent plate boundaries. c. transform faults. d. conservative plate boundaries. e. hot spots.
Active volcanism occurs in association with
a. trenches. b. hot spots. c. ridges. d. all of the above. (Answer) e. none of the above.
The plates typically move at velocities of
a. a few millimeters/yr. b. a few centimeters/yr. (Answer) c. a few meters/yr. d. a few feet/yr. e. a few yards/yr.
Pangaea began to break apart approximately _______ years ago
a. 50 million. b. 100 million. c. 150 million. d. 200 million. (Answer) e. 250 million.
Evidence of the positions of the continents before Pangaea formed comes from
a. fossils on land. b. magnetic data from the continents. c. the locations of old mountain ranges. d. the locations of old continental rock bodies. e. all of the above. (Answer)
Project FAMOUS conducted detailed studies of
a. a portion of the Mid-Atlantic Ridge. (Answer) b. the depths of the Marianas Trench. c. submerged seamounts in the Pacific. d. the Red Sea. e. the East Pacific Rise.
Hydrothermal vents at ridge crests
a. expel hot water that has circulated through the crust. b. are often sites of dense biological communities. c. are areas where chemical deposits rich in metals precipitate on the sea floor. d. all of the above. (Answer) e. none of the above.
Earth's outer core is
a. solid. b. liquid. (Answer) c. gas. d. iron and nickel. e. b and d.
The two seismic waves discussed in the text are body waves that travel rapidly through Earth. These two wave types are called
a. tsunami and roller waves b. G- and D-waves. c. P- and S-waves. (Answer) d. Rayleigh and Love waves. e. none of the above.
Continental crust has a density of _______ g/cm3 and is about _________ km thick on the average.
a. 3.2, 15 b. 2.5, 25 c. 2.0, 45 d. 2.8, 55 (Answer) e. 3.1, 60
Areas where new crust is formed above rising plumes of magma are called
a. spreading centers. (Answer) b. subduction zones. c. pizzerias. d. cold spots. e. leading edges.
Plate tectonics is the theory of moving plates on Earth's surface. The main interactions between plates tend to be at their boundaries. The three main boundary types are
a. divergent, congruent, and trans-American. b. convergent, divergent, and transparent. c. transform, divergent, and convergent. (Answer) d. tangential, circumstantial, and problematical. e. none of the above.
When two continental plates collide
a. one plate is subducted deep into the mantle. b. they are crumpled and deformed. c. one plate may override the other. (Answer) d. oceanic sediments between them are squeezed up into the deformed zone. e. b, c, and d above.
Volcanoes at subduction zones are violent and have a composition of
a. basalt. b. granite. c. egg whites. d. andesites. (Answer) e. endocytes.
Hot spots produce
a. seamounts. b. plateaus. c. guyots. d. a, b, and c above. (Answer) e. none of the above.