Plate Techtonics

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Question Answer
Isostacy is largely a force in the earth acting how? none above
The head of large plumes that form "hot spots" may cause uplift and ____. vast fields of flood basalt
There’q s one place on earth where you can stand on a large island, be above a hot spot, and see MOR all simultaneously. That place is Iceland
Magnetic declination is the angle between the magnetic pole and the geographic pole
Evidence in support of continental drift includes ____. all of the choices are correct
This type of plate boundary the two plates can consist of ocean-ocean, ocean-continent, or continent-continent crust. convergent
The inner wall of a trench consists of a(n) _____ of thrust-faulted and folded marine sediment and pieces of oceanic crust accretionary wedge
The isotopic ages of Hawaiian Island basalts increase regularly to the ____. northwest
Magma heated by ocean-continent convergence may form a(n) _____ such as the Aleutian Islands magmatic (island) arc
Marine geologists can predict the age of igneous rocks of the sea floor by measuring _____. magnetic anomalies
The portion of a fracture zone between two offset portions of ridge crest is called a ____. transform fault
____ is the idea that continents move freely over Earth's surface, changing their positions relative to one another. Continental drift
Sea-floor spreading implies that sea-floor rocks should be ______________. youngest on the crest of mid-ocean ridges
The Himalayan Mountains are thought to have formed ____. by continent-continent convergence
What kind of plate boundary will you find 2 segments of MOR offset? divergent
The downward plunge of cold rock at convergent boundaries accounts for the existence of _____. oceanic trenches
Plumes form ______ that are related to areas of active volcanism such as Iceland, Yellowstone and Hawaii. hot spots
The most common type of transform faults offset oceanic ____. ridge crests
The apparent movement of the magnetic poles through geologic time is called _____. polar wandering
A divergent boundary on the sea floor is associated with ______. mid-oceanic ridges
The basic idea of ______ is that the Earth's surface is divided into a few large plates that move slowly relative to one another. plate tectonics
In this hypothesis the two sides of the mid-oceanic ridge are moving in opposite directions like slow conveyor belts. sea floor spreading
Hess's original hypothesis was that sea-floor spreading is driven by deep mantle ____. convection
Most plates move, each year, approximately 1-12 cm
Measured rates of sea-floor spreading range from ______ cm/year. 1 to 24
Pangea initially separated into two parts, the southern part is called ____. Gondwanaland
After World War II, using extremely sensitive instruments originally designed to detect submarines, it was discovered that the seafloor displayed what? magnetic anomalies
_______ proposed an explanation for magnetic anomalies. Vine and Matthews
Wegener reassembled the continents to form the super continent _____. Pangea
Alaska’s Aleutian Islands, site of some fierce fighting in WWII, are a volcanic island arc
The Peru-Chile trench is moving over the ________ Plate as South America moves west. Nazca
During extension in divergent plate boundaries a rift valley forms as a central ____. graben
Harry Hess proposed that the _______. sea floor moves
In the early 1900s the German meteorologist _____ made a strong case for continental drift. Alfred Wegener
The “action” in plate tectonics, meaning a majority of the earthquakes, mountain-building, and volcanism, mostly takes place near plate edges
These plate boundaries are marked by shallow-focus earthquakes in a narrow zone for a single fault or in a broad zone for a group of parallel faults transform
One kind of convergent plate boundary is ____. continent-continent convergence
When a descending plate reaches a depth of _______ km, magma is generated in the overlying asthenosphere. 100
The Rift Valley in East Africa is an example of a _____. diverging plate boundary
In plate tectonics, intense geologic activity occurs at ____. plate boundaries
Young mountain belts with their associated igneous intrusions, metamorphism, and fold-thrust belts form at _______. convergent boundaries
Plate motion can be measured directly using ____. GPS
The San Andreas Fault is _________ in California. a right lateral transform fault
Alternating positive and negative polarity magnetic anomalies in the crust form a stripe-like pattern parallel to _____. mid-oceanic ridges
A _____ plate boundary is where plates are moving away from each other. divergent
Divergent plate boundaries can occur where spreading occurs under a continent, for example ___. the Red Sea
India began colliding with Asia about 30 million years ago. The most likely thing that will happen in the geologic future is that It will halt and be “sutured” onto the south side of Asia
____ volcanoes can be found along subducting plate boundaries. Andesitic
One possible mechanism for plate tectonic drive is ____. slab pull
The ___ includes rocks of the crust and uppermost mantle. lithosphere
What may well happen to old, subducted lithospheric plates (OCTL) they sink down to the core

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