48 terms

Plate Tectonics

Which of the following observations was included as evidence for Wegener's continental drift hypothesis?
the jigsaw-puzzle fit of the continents
Which one of the following statements is TRUE?
Earth's magnetic field reverses over geologic time.
Beneath Earth's lithosphere, the hotter, weaker zone known as the _____ allows for motion of Earth's rigid outer shell
Which boundary is characterized as a long, linear rise in the seafloor, with shallow earthquakes and volcanic activity found along its length?
divergent boundary
Deep-ocean trenches are formed by _______.
the subduction of lithosphere into the asthenosphere
The Atlantic Ocean basin is getting _____ in size because _____
larger; no subduction is taking place at the basin's perimeter
Which of the following is one of the remarkable realizations associated with the discovery of seafloor spreading?
The crust of the oceans is very young relative to the age of the continental crust
The slowly increasing distance between South America and Africa is due to
seafloor spreading
Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from
a hot spot
Layered _________exposed by erosion can be seen when looking at the Grand Canyon in the United States
sedimentary rock
Australia is composed of relatively old and thick
continental crust
The extremely deep ocean Marianas Trench is a result of
____found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.
Seafloor crust
The earthquakes that occur in Southern California generally occur above a
_______ was a flora that was widely distributed throughout the once contiguous, late Paleozoic, Southern Hemisphere landmass.
In the early part of the 20th century, ________ argued forcefully for continental drift.
Alfred Wegener
Which of the following paleoclimatic evidence supports the idea of the late Paleozoic super continent in the Southern Hemisphere?
tillites (rocks formed by glaciers) in South Africa and South America
The ________ is an example of an active, continent-continent collision
northward movement of India into Eurasia
Deep-focus earthquakes, those between 300 and 700 kilometers below the surface, occur only in association with _______
subduction zones
A very long-lived magma source located deep in the mantle is called a _____
hot spot
Linear, magnetic patterns associated with mid-ocean ridges are configured as ________.
normal and reversed magnetized strips roughly parallel to the ridge
The continental drift hypothesis was rejected primarily because Alfred Wegener could not ________.
identify a mechanism capable of moving continents
_____ was never proposed as evidence supporting the existence of Pangaea.
Islands along the Mid-Atlantic Ridge with rocks dating back from 542 million to 2500 million years ago
A transform plate boundary is characterized by ________.
a deep, vertical fault along which two plates slide past one another in opposite directions
________ first related the symmetrical magnetic patterns in seafloor basalts to seafloor spreading at a mid-ocean ridge.
Vine and Matthews
Which of the following lithospheric plates is not included among the seven largest?
the Philippine plate
Earth's lithospheric plates are composed of crust and which of the following layers?
the outermost portion of the mantle
Which of the following processes can be observed at the margins of lithospheric plates?
earthquakes, faults, volcanoes, and mountain building
In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?
Due to tectonic activity, rocks on the ocean floor are continually recycled.
Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring. What type of plate boundary is this?
a convergent plate boundary
divergent plate boundaries
move apart.
convergent plate boundaries
Plates move together.
transform plate boundaries
move side-by-side
What forms at divergent plate boundaries
new oceanic lithosphere
In general, where do volcanoes form in subduction zones?
on the overriding plate, away form the convergent boundary
Why are volcanoes NOT found at transform boundaries?
Transform boundaries do not cause changes to the pressure, temperature, or composition of the mantle.
The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?
an ocean
At divergent plate boundaries, new ocean crust is created
Movement of plates away from each other at divergent boundaries typically shows which of the following average velocities?
5 cm per year
When moving away from a divergent boundary in either direction, which of the following statements is true?
The rocks increase in age.
Which geologic features are associated with divergent boundaries?
mid-ocean ridges and continental rift valleys
What is the relationship between the crust and lithosphere?
The crust is part of the lithosphere.
Which geologic features are associated with convergent boundaries?
ocean trenches and volcanoes
Where is the youngest ocean floor found?
along the crest of mid-ocean ridges
What would happen to Earth if ocean floor were created at divergent boundaries at a faster rate than it is destroyed at convergent boundaries?
The Earth would increase in volume.
What is a volcanic arc?
a row of volcanoes that forms on the overriding plate near a subduction zone
Which of the following mountain ranges are examples of continental arcs
Andes and Cascades
Why people didn't believe in Alferd
Because he didn't have a Magnetism