Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
51 Cards in this Set
- Front
- Back
who wrote the hypothesis called continental drift, and what did it challenge?
|
alfred wegener; the long held assumption that the continents and ocean basins had fixed geographic positions
|
|
what did wegener suggest? what was it called?
|
that a single supercontinent consisting of all earths landmasses once existed; pangaea
|
|
evidence of wegener's supercontinent hypothesis
|
fossils in rocks from both s.america and africa; continental drift was evident
glacier movement similar rocks and mountains on both sides of the atlantic |
|
one of the main objections to wegeners supercontinent hypothesis
|
his inability to identify a credible mechanism for continental drift
|
|
who came up with a credible mechanism for contintental drift?
|
tuzo wilson; 1969
|
|
earths layers are what
|
crust > upper mantle > lower mantle > outer core > inner core
|
|
what is the contintental crust made of
|
granitic-andesitic
|
|
what is the oceanic crust made of
|
basalt
|
|
the aesthenosphere is apart of what earth layer
|
upper mantle
|
|
in a convergent boundary, the lithosphere is subducted into the (c+o)
|
aesthenosphere
|
|
what makes up the lithosphere
|
earths crust and the upper most/coolest part of mantle; strong layer
|
|
Earths hotter, weaker region in the mantle that lies below the lithosphere
|
aesthenosphere
|
|
earths outer shell is effectively detached from the aesthenosphere and allows the layers to move independenly, is because....
|
pressures/temps in the upper aesthenosphere are such that rocks at this depth (100-200 km) are very near their melting point, and flow; where as the lithosphere tends to respong to forces by bending or breaking, but not flowing
|
|
type of boundaries
|
divergent
convergent transform |
|
divergent boundaries have what type of magma come up from the spreading center, and what type of earthquakes are formed
|
basalt magma; shallow, focus is shallow in the earth
|
|
give an example of a divergent boundary
|
mid atlantic ridge
|
|
examples of divergent boundaries on land
|
east african rift
iceland |
|
where is the rift valley
|
place between spreading plates during a divergent boundary
|
|
a trench develops during what
|
subduction zone with oceanic lithospheres subducting
|
|
O + O subduction zones produce whar type of magma, there for form what type of volcanoes
|
felsic to intermediate, composite cones
|
|
the aleutian islands in alaska are an example of what type of boundary
|
o + o subduction
|
|
what are formed as a result of o + o subduction
|
volcanic island arcs
|
|
what forms from a o+ c subduction
|
continental volcanic arcs
|
|
o + c subduction zones create what type of magma and volcanoes
|
felsic-intermediate; composite
|
|
name some c + c subduction characteristics
|
start off as o + c
produces extreme deformation of rocks, metamorphism and faulting |
|
name some characteristics of convergent boundaries
|
are of earthquakes, volcanoes and other igneous activity
viscous magma composite cones; high silica content magma+violent eruptions plutons form when magma doesnt reach surface area of mountain building crust melts parially or fully |
|
what can form if magma does not reach surface during both an o + o, and o + c subduction
|
pluton (granite or diorite)
|
|
magma that does reach the surface during an o + o and o + c subduction, will be what
|
rhyolite or andesite
|
|
example of o + c subduction
|
andes mt, cascade range in WA and oregon
|
|
c + c subduction can produce
|
mountain ranges
either volcanic or continental volcanic arc composite volcanoes if present |
|
example of c + c subduction
|
himalayas
|
|
divergent boundaries mostly occur where
|
under oceans
|
|
during a divergent boundary, crust being older as one goes away from the ridge...t or f
|
true
|
|
low viscous magma; less violent volcanism
|
divergent boundary
|
|
horizontal movement between plates; new crust is not created or destroyed
|
transform boundary
|
|
allows for spreading to occur along divergent and convergent boundaries
|
transform boundary
|
|
generally no volcanism in what type of boundary
|
transform
|
|
earthquakes can occur from a transform boundary...t or f
|
true
|
|
example of a transform boundary
|
san andreas fault
|
|
is hot spot volcanism associated with a plate boundary?
|
no
|
|
hot spot volcanism can occur where
|
on either contintent or in ocean
|
|
characteristics of hot spot volcanism
|
mantle plume comes up through crust
stay stationary as crust moves over it |
|
examples of hot spot volcanism
|
yellowstone
hawaii |
|
proof that plates are moving
|
hotspots
thickeness of sediments-away from spreading center ocean drilling magnetic reversal polar wandering |
|
does not occur at a boundary, accumulation of sediments, depositor of flat lying undisturbed sediments
|
passive margin
|
|
occurs during the transition of oceanic to continental crust, on top of oceanic crust
|
passive margin
|
|
no tectonic activity, flat lying
|
passive margin
|
|
deformed, sedimentary and igneous ex (basalt) folding and faulting
|
accretionary wedge
|
|
occurs at all subduction zones, in between 2 plates as one plate subducts
|
accretionary wedge
|
|
earthquakes may happen at this boundary, but no volcanism
|
transform fault
|
|
all subduction zones have what
|
trenches
accretionary wedge granitic - andesitic magma composite volcanoes |