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GEO LECTURE > Ocean > Flashcards

Ocean Flashcards

1
Q

Why is Earth called the blue planet?

A

71% water (oceans and seas)

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2
Q

Are oceans and continents divided evenly btw northern and southern hemisphere

which is the water hemisphere and which is the land hemisphere

A

no

water: southern; land: northern

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3
Q

List the major ocean basins in order from biggest to smallest

A

Pacific, Atlantic, Indian, Arctic

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4
Q

What is the largest ocean?

A

Pacific

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5
Q

What is the deepest ocean?

A

Pacific

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6
Q

What ocean makes up most of the sourthern hemisphere?

A

Indian

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7
Q

What is the fifth “ocean” but it really isn’t an ocean?

A

Antarctica/southern ocean

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8
Q

definition of salinity

A

total amount of solid material dissolved in water

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9
Q

what is the difference btw % and %o?

A

%: parts per hundred
%o: parts per thousand

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10
Q

what is the salinity of seawater?

% and %o

A

3.5%
35%O

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11
Q

If 35%o of seawater are salts, what is the rest?

A

water

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12
Q

Of the 35%o (salts), most of the salt in seawater is…

A

sodium chloride (NaCl)

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13
Q

Of the 35%o, what are the other salts other than table salt?

what percent of the 35%o do these salts combined with table salt equal

A

SO
Mg
Ca
K

99%

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14
Q

TF: does saltwater contain all of Earth’s naturally occurring elements

A

yes

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15
Q

What are the two most abundant elements that contribute to the ocean’s salinity?

A

Na: sodium
Cl: chlorine

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16
Q

What are the two sources of sea salts?

A
  1. chemical weathering of continental rocks delivered to the ocean via streams
  2. Earth’s interior via volcanic eruptions through outgassing (source of water in oceans and atmosphere)
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17
Q

Why has the composition of sewater been stable for so many years?

A

material is removed just as rapidly as material is added

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18
Q

What is the cause behind variations in salinity

A

change in water content

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19
Q

if you decrease salinity, what is being added

A

freshwater

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20
Q

what things decrease salinity

A

precipitation
runoff
melting of icebergs/glaciers/sea ice

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21
Q

What things increase salinity?

A

formation of sea ice
evaporation

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22
Q

Where is evaporation the highest?

A

subtropics (25N-35N;25S-35S)

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23
Q

Where is precipitation the highest?

A

the equator and mid latitudes

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24
Q

What occurs at polar regions?

A

melting and formation of sea ice varies seasonally

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25
Q

what ocean is the saltiest?

A

Atlantic

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26
Q

Where do you find a three-layered structure?

what are the three layers

A

open ocean

mixed/shallow surface layer, thermocline/transition zone, deep zone

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27
Q

What changes with depth in the ocean?

A

temp and salinity

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28
Q

Describe the surface temperatures of equatorial regions vs polar regions

A

surface temps higher at equator than at poles

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29
Q

Temp variations and depth: low latitudes

thermocline presence

A

high surface temp (equator) but decreases with depth

yes

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30
Q

thermocline definition and range in meters

A

rapid change of temp with depth

300 to 1000m

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31
Q

temperature and depth: high latitude
- what does the line look like
- seasonal changes

thermocline presence

A

low surface temp (polar) has similar temp as you go deeper
- vertical line
- surface temp might be warm in summer, so might have weak thermoclines seasonally

no, it’s isothermal

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32
Q

What does density determine

A

water’s vertical position in ocean

33
Q

if water has low density what is its position in ocean vs high density water

freshwater vs seawater

A

low: at top
high: sinks

freshwater: low; seawater: high

34
Q

Whaat are the two factors that affect density

A

salinity and temp

35
Q

density:
increase salinity vs decrease salinity

A

increase: more dissolved subst.=more dense
decrease: less dissolved substances=less dense

36
Q

density:
increase temp
decrease temp

what kind of relationship is this

A

increase: expanding atoms, less dense
decrease: compacting atoms, more dense

inverse

37
Q

what is the most influential influencing factor of density and 3 reasons why

A

temp
1. polar regions: surface and deep ocean layers are similar, only salinity is a significant factor
2. high salinity (more dense) water on top of low salinity (less dense) if its warmer
3. more variations

38
Q

Density and depth:
low latitude

what kind of -cline does it have or not have

A

equator: low density (high surface temps) but density increases with depth bc temp decreases

has pycnocline

39
Q

pycnocline definition

A

rapid change of density with depth from 300 m to 1000m

40
Q

Density and Depth:
high latitude
- what kind of line does this make

what kind of -cline does it have or not have

A

polar: high density (low surface temp) so density stays similar to surface layer
- vertical

no pycnocline, isopyncocline

41
Q

What is the surface mixed zone?

describe the temperature and why it is the way it is

A

layer with uniform temperature
distribution of heat/mixing by tides and currents

42
Q

what percent of ocean water does the surface mixed zone make up

A

2

43
Q

what percent of ocean water does transition zone make up

deep zone

A

18

80

44
Q

Why doesn’t 3 layers occur at high latitudes? what does occur?

A

isothermal and isopycnal
mixing with surface and deep waters=deep ocean currents

45
Q

wha tkind of -cline does the halocline correspond with

A

thermocline mirrors halocline

46
Q

if the temp is high, what’s the salinity
if temp is low, what’s the salinity

A

low
high

47
Q

halocline

A

rapid salinity change btw 200m and 800m

48
Q

sonar

aka

A

echosounders

49
Q

how does sonar work

A

sends outgoing signal and comes back as a reflected signal, measures depth by seeing how long it takes to reflect

50
Q

sidescan sonar

A

used to see shape of ocean floor by sending fans of sound

51
Q

multibeam

A

send fans of sound (shape) and record reflected signals (depth)

52
Q

do satellites measure depth of ocean

A

no, shape

53
Q

what are passive cont.margins

eq/volcanic activity

A

inactive regions far from plate boundaries

weak

54
Q

how do passive cont. margins develop

A

rifitng of continents and separated by sea floor spreading

55
Q

what are the features of passive continental margins

A

cont. shelf, slope, rise

56
Q

continental margins

A

outer margins of continents where continental crust transitions to oceanic crust

57
Q

continental shelf

A

flooded extension of continent, gently sloping

58
Q

continental slope

A

barrier btw c.c and o.c

59
Q

how doe seasonal chnages in the amount of sea ice at the poles influence the salinity of the water? is water density greater before or after the ise ice forms?

A

ice forms: increases salinity
ice melts: decreases salinity
more dense after it forms

60
Q

cont. rise

A

thick accumulation of sediment from slope to ocean floor

61
Q

how is cont. rise created

A

sediments from turbitity currents ggo down submarine canyons to make fans which accumulate to form rise

62
Q

why is there larger abyssal plains in the atlantic

A

trenches are absent

63
Q

what are the three provinces of the seafloor and what are their features

A

continental margin: shelf, slope, rise
deep-ocean basin: abyssal plain, seamount, trench, guyots, plateaus
mid ocean ridge: rift valley
deep ocean basin
continental margin

64
Q

What are active continental margins

processes happening

trenches

A

along convergent plate boundaries (o.c vs c.c)

accretionary wedge+subduction erosion (sediment scraped off –> mantle

deep with erosion, shallow w accretion

65
Q

where are passive continental margins

A

atlantic

66
Q

where are active continental margins

A

pacific

67
Q

trenches how do they form

A

long narrow troughs
- convergent plate boundaries (subduction)

68
Q

abyssal plains

what are they interrupted by>

A

deep flat structures that are accumulations of ssediment that cover otherwise ruddeg seafloor

seamounts

69
Q

are abyssal plains found in all oceans?

A

yes

70
Q

seamounts

where are they most common

A

submarine volcanoes

pacific

71
Q

volcanic island

A

volcano that grows large enough before carried away from magma source

72
Q

guyots

A

submerged flat topped sseamounts

73
Q

how do guyots form

A

inactive volcanic islands are lowered to sea level by weathering and erosion and are moved away from ridge or hot spot where they formed and sink

74
Q

oceanic plateaus

A

vast outpourings of basaltic lava

75
Q

earth

what is the longest topographic feature on

A

oceanic ridge system

76
Q

what is the mid ocean ridge system offset by

A

transform fault

77
Q

rift valleys

A

deeo down faulted structures on axis of ridge system

78
Q

how does oceanic crust change as it moces away from mid ocean ridge

A

cools, denser, older as it gets farther from mid ocean ridge and upwelling zone as it enters basin
( seawater circulation in pores and fractures)

increasse in lithosphere thickness away from ridge bc asthenosphere cools to become ltihosphere

79
Q

where is the thickest sediments found

A

away from oceanic ridge, near continental margins, most trenches

GEO LECTURE (19 decks)

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