Ocean Flashcards by Jaz Meza

Why is Earth called the blue planet?

71% water (oceans and seas)

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Are oceans and continents divided evenly btw northern and southern hemisphere

which is the water hemisphere and which is the land hemisphere

water: southern; land: northern

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List the major ocean basins in order from biggest to smallest

Pacific, Atlantic, Indian, Arctic

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What is the largest ocean?

Pacific

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What is the deepest ocean?

Pacific

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What ocean makes up most of the sourthern hemisphere?

Indian

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

Antarctica/southern ocean

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definition of salinity

total amount of solid material dissolved in water

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what is the difference btw % and %o?

%: parts per hundred
%o: parts per thousand

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what is the salinity of seawater?

% and %o

3.5%
35%O

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

water

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

sodium chloride (NaCl)

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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

SO
Mg
Ca
K

99%

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

yes

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

Na: sodium
Cl: chlorine

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What are the two sources of sea salts?

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

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

material is removed just as rapidly as material is added

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What is the cause behind variations in salinity

change in water content

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if you decrease salinity, what is being added

freshwater

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what things decrease salinity

precipitation
runoff
melting of icebergs/glaciers/sea ice

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What things increase salinity?

formation of sea ice
evaporation

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Where is evaporation the highest?

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

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Where is precipitation the highest?

the equator and mid latitudes

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What occurs at polar regions?

melting and formation of sea ice varies seasonally

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what ocean is the saltiest?

Atlantic

Where do you find a three-layered structure? | what are the three layers

open ocean | mixed/shallow surface layer, thermocline/transition zone, deep zone

What changes with depth in the ocean?

temp and salinity

Describe the surface temperatures of equatorial regions vs polar regions

surface temps higher at equator than at poles

Temp variations and depth: low latitudes | thermocline presence

high surface temp (equator) but decreases with depth | yes

thermocline definition and range in meters

rapid change of temp with depth | 300 to 1000m

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

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

What does density determine

water's vertical position in ocean

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

low: at top high: sinks | freshwater: low; seawater: high

Whaat are the two factors that affect density

salinity and temp

density: increase salinity vs decrease salinity

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

density: increase temp decrease temp | what kind of relationship is this

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

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

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

Density and depth: low latitude | what kind of -cline does it have or not have

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

pycnocline definition

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

Density and Depth: high latitude - what kind of line does this make | what kind of -cline does it have or not have

polar: high density (low surface temp) so density stays similar to surface layer - vertical | no pycnocline, isopyncocline

What is the surface mixed zone? | describe the temperature and why it is the way it is

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

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

what percent of ocean water does transition zone make up deep zone

18 | 80

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

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

wha tkind of -cline does the halocline correspond with

thermocline mirrors halocline

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

low high

halocline

rapid salinity change btw 200m and 800m

sonar | aka

echosounders

how does sonar work

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

sidescan sonar

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

multibeam

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

do satellites measure depth of ocean

no, shape

what are passive cont.margins | eq/volcanic activity

inactive regions far from plate boundaries | weak

how do passive cont. margins develop

rifitng of continents and separated by sea floor spreading

what are the features of passive continental margins

cont. shelf, slope, rise

continental margins

outer margins of continents where continental crust transitions to oceanic crust

continental shelf

flooded extension of continent, gently sloping

continental slope

barrier btw c.c and o.c

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?

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

cont. rise

thick accumulation of sediment from slope to ocean floor

how is cont. rise created

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

why is there larger abyssal plains in the atlantic

trenches are absent

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

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

What are active continental margins | processes happening ## Footnote trenches

along convergent plate boundaries (o.c vs c.c) | accretionary wedge+subduction erosion (sediment scraped off --> mantle ## Footnote deep with erosion, shallow w accretion

where are passive continental margins

atlantic

where are active continental margins

pacific

trenches how do they form

long narrow troughs - convergent plate boundaries (subduction)

abyssal plains | what are they interrupted by>

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

are abyssal plains found in all oceans?

yes

seamounts | where are they most common

submarine volcanoes | pacific

volcanic island

volcano that grows large enough before carried away from magma source

guyots

submerged flat topped sseamounts

how do guyots form

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

oceanic plateaus

vast outpourings of basaltic lava

# earth what is the longest topographic feature on

oceanic ridge system

what is the mid ocean ridge system offset by

transform fault

rift valleys

deeo down faulted structures on axis of ridge system

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

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

where is the thickest sediments found

away from oceanic ridge, near continental margins, most trenches