oceanography

Question 1

general geography

Answer 1

71% of surface is ocean or marginal sea

south hemisphere mostly water

Question 2

four main ocean basins

Answer 2

pacific-largest & greatest in depth
atlantic- half size of pacific & not as deep
indian- slightly smaller than atlantic; largely s. hemi body
arctic- 7% size of pacific

Question 3

passive continental margin

Answer 3

not assoc w/ plate boundaries (Atlantic Coastline)
experience little volcanism
few earth quakes

Question 4

active continental margin

Answer 4

ocean lithosphere subducted beneath continents
pacific rim
assoc with deep ocean trenches

Question 5

passive

Answer 5

continental shelf
slope
cont rise
submarine canyons & turbidity currents
deep sea fan

Question 6

continental shelf

Answer 6

flooded extension of continent
gently sloping from shoreline to deep ocean
thick accumulation of shallow water sediments
contains oil & important mineral deposits

Question 7

continental slope

Answer 7

seaward edge of continental shelf

boundary btwn ocean & continental crust

Question 8

continental rise

Answer 8

slope become more gradual incline

turbidity currents follows submarine canyon

Question 9

submarine canyons & turbidity

Answer 9

deeps steep sided valleys cut into cont slope
some are seaward extensions of river valleys
most appear to be eroded away from turbidity currents

originate along cont slope
downslope movement of dense sediments- laden water
deposits are called turbidites
sediment deposit show graded bedding

Question 10

deep sea fan

Answer 10

dense muddy currents emerge from the mouth of a canyon onto the relatively flat ocean floor
deposits form a fan

Question 11

active

Answer 11

subduction
volcanic activity
continental slope descends into deep sea trench
accumulation of deformed sediments & scraps of ocean crust form accretionary wedges
may have little or no accumulation of sedimenets

Question 12

deep ocean basins

Answer 12

trenches
abyssal plains
guyots
plateaus

Question 13

trenches

Answer 13

long relatively narrow features
deepest parts of ocean
  challenger deep, marianas: 11022 m
most located in pacific ocean
ocean lithosphere plunge into mantle
generates earthquakes
assoc with volcanic activity
pacific "ring of fire"
volcanic island arcs
continental volcanic arc

Question 14

abyssal plains

Answer 14

likely the most level places on earth
sites of thick accumulation of sediments
found in all oceans

Question 15

seamounts, guyots, and oceanic plateaus

Answer 15

seamounts- isolated volcanic peaks
many form near oceanic ridges, still volcanic activity and still grow
guyots- tablemounts , submerged flat top volcanoes, dormant, become flat top by wave action
oceanic plateaus- similar to continental flood basalt provinces

Question 16

oceanic ridge system

Answer 16

70,000km long
crest stands 2-3km above adjacent ocean basin
divergent plate boundaries- new crust created

Question 17

ocean ridge

Answer 17

broad features-not narrow as ridge would imply
1,000-4,000 kn wide
broken into segments 10-100s km long
segments separated by transform faults
consists of layers of newly transformed basalitc rocks

Question 18

rift valleys

Answer 18

deep down faulted structures along ridge crest
50 km wide 2,000 m deep
volcanic cones common
rugged topography
similar to continental rift valley (E. Africa)

Question 19

types of seafloor sediments

Answer 19

terrigenous
biogenous
hydrogenous

Question 20

terrigenous sediment

Answer 20

material weathered from continental rock
fine particles remain suspended for long time
oxidation often produces red & brown colored sediments
deposition rate 1 cm/50,000 yrs
continental margin area

Question 21

biogeneous sediment

Answer 21

shells, skeletons of marine animals & plants
most common: calcareous oozes produces from microscopic organisms
siliceous oozes- skeletons of diatoms & radiolarians
phosphate rich materials-bones, teeth and scales of fish, & other organisms

Question 22

hydrogenous sediment

Answer 22

minerals that crystallize
most common type- manganese nodules, calcium carbonates, metal sulfides, evaporites
only small portion deposits in ocean

Question 23

composition of sea water

Answer 23

consists of 3.5% dissolved minerals
avg. salinity is 35%
major constituents is sodium chloride

Question 24

salinity

Answer 24

total amt of solid material dissolved in water
brackish-mix of fresh & sea water (estuaries &deltaic environ)
hypersaline- excessive salinity, avg 42% (Red Sea, Dead Sea, Great Salt Lake)
halocline- zone of rapid change in salinity btwn depths of 300-1000 m
low latitudes- low salinity
high latitudes- high salinity

Question 25

process that affect salinity

Answer 25

low salinity- precipitation, runoff from land, iceberg melting, sea ice melting,
high salinity- evaporation, formation of sea ice