test 2

magmas that form beneath spreading ridges as a result of mantle plumes are:
mafic( basalt)
viscosity is controlled by _____ & _______
temperature and composition
which magma is hotter, has less silica and therefore flows better(low viscosity)?
A: mafic
: word that describes resistance to flow
A: viscosity
Q: felsic magma is hotter than _______ degrees
A:900c
Q:mafic magma is hotter than_____degrees
A 1200c
Q: silica poor, iron and magma rich?
A:intermediate
Q:silica rich, iron & mag. Poor?
A: felsic
Q: primary constituent of magmas?
A: silica
Q: mineral composed of silica tetrahedre?
A: silicates
Q: Most abundant elements in the crust?
A: silicon & oxygen
Q: Magma erupts either as(2):
A:Lava flows, pyroclastic flows
Q: The Difference between magma and lava?
A: Magma- below the surface, Lava- above the surface
which is more viscous: magma at mid ocean rides or @ sub. zones?
sub. zones
huge thick flat laying layers of basalt that originate from hot spot activity
flood basalts
What does Bowens series explain?
how one magma can generate different rock types
lava made up of angular blocks
AA Lava
lava w/ smooth surface like taffy
pahoehoe
bulbous, interconnection masses that result from underwater eruption of basaltic lavas
pillow lavas
volcano w/ gentle slopes, rounded shapes, composed of basalt, hawaiian, non explosive, pose little danger to humans, mafic
shield
consist of cinder-like pyroclastic materials, relatively small, steep sloped cones
cindercone
composed of lava flows & layers of pyro materials ontop, mud flows, explosive, most dangerous to humans
composite (strato)
large oval to circular depression that forms when the summit of a V collapses into its magma chamber
caldera
formed when viscous, felsic lavas are formed up thru the conduits of some Vs
lava domes
mafic magma is likely to form what kind of volcano?
shield
what kind of lava doesnt flow?
rhyolithic
sheet-like eruptions of pyro materials, can cover large areas
pyro sheet deposits
What type of Vs are the Aleutians ? and why?
strato, associated w/ a subzone
Hawaiian Vs are what type? why?
shield, hot spot
what kind of V has steep sides?
strato
runoff occurs when rain fall exceeds
infiltration capacity
water moves like film over surface
sheet flow
runoff is combines in channels
channel flow
change in elevation/ change in distance
gradient
measure of distance water travels in a given amount of time
velocity
volume of water that passes a given point in a givenamount of time
measure discharge
stream-gauging station
main stream of river including all its tributaries
drainage system
geographic area that is seperated from adjacent drainage basins by divides
drainage basin
size of largest particle a stream can move
competence
total sediment load a stream can carry
capacity
competence depends on:
water velocity
capacity depends on:
velocity and water volume
salts in solution
dissolved load
gives moving water its color
suspended load
term for material that was being carried in a river and is now deposited in sediment
alluvium
stream that has too much sand and gravel to effectively transport, s and g asre deposited as bars that divide the main channel
braided stream
stream that carries suspended load and has a single channel
meandering stream
point bar is erosion or deposition?
deposition
meander neck is erosion or deposition?
erosion
flat lowland areas paralleling streams
flood plains
alluvial deposits accumulated at the mouth of a stream
delta
lobate deposits of gravel and sand on land
alluvial fan
renewed stream downcutting thru flood plain deposits
stream terraces
flood water deposits at edges of flood plain
natural levee
shows stream discharge or water depth over time
hydrograph
term describes how high the river has to be before its considered a flood
flood stage
average time between floods, events of a certain size
recurrence interval
the changing of existing channels
channelization
does channelization change velocity?
yes
the downslope of material resulting from gravity
mass wasting
mass wasting occurs when:
gravitational forces > shear strength
forces that help maintain slope stability
shear strengh