overripe oceans

wave steepness max non-break ratio

1/7

wave base

½ wave height

saltiest ocean

atlantic

deepest ocean

pacific

how much phytoplankton in cubic meter of water

20,000

______ % plate boundaries in ocean

90%

convergent boundaries: ocean ocean (wh + feats)

denser (older) one subduction, makes deep trenches, volcanic island arcs, basaltic lava

convergent boundaries: continent to ocean (wh + feats)

ocean subducts, making trench and continental volcanic arc

convergent boundaries: continent to continent (wh + feats)

continent to continent, folds and deforms crust and makes uplifted mountains, intervening ocean crust is subducted

divergent boundaries

• common as mid ocean ridges

• oldest at trench, youngest crust at ridge

transform bondaries

occurs perpendicular to mid ocean ridges

inactive faults

called fault zones and act as scars to show past plate movement

intraplate volcanism

hotspots arising from mantle plumes and can make islands

nematath

hotspot track made as ridge moves over

paleomagnetism

bc igneous rocks usualy has magnetite that aligns with earths magnetic field when melted then stays fixed.

wilsons cycle

about how oceans form,

1. uplift creates valley

2. divergence creates narrow seas with matching coast, then ocean basin with continental margins

3. convergents creates island arcs + trenches, then eventually shrinks sea and creates young mountains

4. uplift and convergence creates young/mature mountain bels

epipelagic

0-200m mixed surface layer where oxygen decreases with depth and has a seasonal thermocline, not that much nutrients because photosynthesis consumes it

mesopelagic

200-1000m contains oxygen minimum layer w lots of nutrients (bc marine snow, etc) and permanent thermocline

bathypelagic

1000 - 4000m oxygen increases with depth

abyssaopelagic

>4000m in trenches

euphotic

zone where photosynthesis can occur ~0-100m

photic zone

zone to where light penetrates (at most 200 m)

disphotic zone

zone where light penetrates but no photosynthesis

aphotic zone

no light reaches

passive margin characteristic

well developed continental rise with deep thick sediment and no tectonic activity

convergent active boundaries caracteristic

onshore active volcanoes, narrow shelf, steep slope, offshore trench

accretionary wedge

where sediment/ crust is scraped from the subducting plate

continental shelf

VERY gentle slope from shore to shelf break, basically the part of continental crust transitioning to oceanic crust

continental slope

often boundary between ocean and continent crust, which is a steep slope down to the level of ocean basin

continental rise

graded bedding slope which is the final transition between continent and ocean, it is beyond the continental slope

turbidity currents

underwater avalanche of sediment down the continental slope, causes a lot of erosion

submarine canyons

BIG canyons in the continental shelf

mid ocean ridge description

continuous + fractured mountain range in all ocean basins, which is lifted up because its made of less dense newly formed crust that is pushed up by mantle. lots of volcanic activity

mid ocean ridge features

seamounts, pillow lavas,

fault zones

extensions of transform faults that show past movements

ocean basin

30% of earths surface, aka abyssal plain, which is very smooth bc covered in a deep layer of fine sediments

seamount

a underwater volcanic mountain that is more than 1km high

guyot/tablemount

a seamount with a flat top

abyssal hill/sea knoll

lots of these, which usually have rounded tops; less than 1 km tall

shield volcano

broad large volcanoes that form most seamounts

sill

a “speed bump” of the ocean floor, not very high raised ridge that restricts flow a little

forearc basin

flat basin in front of the trench caused by the accretionary arch

shore

low tide to highest point affected by storm waves

foreshore

low to high tide

coast

shore to as far as ocean related features are seen

beach

deposit of waveworked shore sediments

wavecut bench

flat, wave eroded surface that sediment moves over

longshore bar

sand bar parallel to cost that can trip waves

longshore trough

trough of the longshore bar

berm

high tide to coastline

sand movement w/ light waves

swash soaks in sand, dominates ,so deposition

heavy waves

not as much swash soaks in so more backwash, so erosion

summer beach

lighter waves = wide berms, steep beach face, little to no longshore bar

wintertime beach

heavy wave activity, narrow berm, gently sloping beach face with longshore bar

3 beach compartment

1) rivers/coastal erosion that supply sand 2) longshore transport 3) offshore canyon where sand is drained away from beach

erosional shores

places w/ tectonic uplift, so have rocks and cliffs

erosional shore features

wave cut cliffs > sea caves > sea arches > sea stacks

waves concentrate at headlands

depositional shores

lots of sasnd deposits

spit

linear ridge of sediment extending from longshore drift direction into a bay

baymouth bar

when bay opening not cleared by currents, a spit extension forms

tombolo

a sand ridge connecting island to mainland, forming in island wave shadow

barrier island

long ofshore deposit of sand parallel to coast

lagoon

between barrier island and shore

barrier island migration

it rolls over on itself and they are currently moving towards land bc rising sea level

deltas

triangular sediment deposits at river mouth that deposit more than longshore drift can take away, they are very fertile

emerging coastlin

has marineterraces and stranded beach deposits, also cliffs etc

submerging coastline

drowned beaches, river valleys

relative sea level changes

local sea level change due to tectonic, isostatic adjustment

isostatic adjustment

land rising/sinking bc weight of ice from before/now

eustatic sea level changes

worldwide changes bc of seawater volume or ocean basin capacity changes, ex formation/destruction of large lakes, seafloor spreading, ice ages

coastal water properties

• low salinity w/ halo cline

• prevailing dry offshore winds

  • only isohalinen if shallow w/ significant tidal mixing

coastal waters properties at dif latitudes

low: warm (up to 45 C), isothermal with no mixing con open ocean

mid: summer = shallow warm, winter = cool + sinking, small thermocline

high: uniform cold of about -2c (isothermal)

estuary

partially enclosed coastal waters that are diluted by freshwater from rivers

coastal plain estuary

flooded river valley

fjord

flooded glaciated valley, and u shaped walls (may have sill as well)

coastal wetland

where watertable is at the surface so saturated hydric soils, ex coastal swamps, tidal flats, etc

freshwater lens/ghyben herzberg lens

convex layer of fresh groundwater that floats about denser saltwater usually in small coral/limestone islands/atolls

reef development

fringing > barrier > atoll

fringing reef

develop on margin of landmass when suitble conditions (esp active volcanos), development will stop if land does not subside or sea level not rise

barrier reef

reefs separated from landmass by well-developed lagoon

atoll

a circular reef that encloses a lagoon, no landmass inside

where does general surface circulation occur

in and above pynocline (=< 1000 m), about 10% of ocean.

wind transfers ___ energy in speed

2%

subropical gyres

5 gyres, in N/S pacific and atlantic, also indian ocean

• 3 yrs to circle small gyre, 6 yrs for large

4 currents of gyre

1. equatorial (westward current)

2. western boundary (warm water)

3. N/S boundary (flows east bc westerlies wind)

4. eastern boundary current (cold and deflected to equator by coriolis and land barriers)

equatorial countercurrent

east flowing current caused by gravity (bc equatorial current piles of a hill of water thatn wnats to go down)

subpolar gyres

flows opposite of st gyres, above 60 degrees, when boundary currents flow into high latitueds and are then pushed by polar easterlies

ekman transport

net transport 90 to the right of wind but only in ideal conditions so usually 70

el nino period

• trade winds get weaker or even reverse

• east pacific warms up + thermocline becomes deeper + lower pressure (more rising air)

• warmer and negative.

• el nino 3.4 region becomes 0,5 C hotter.

bjerknes feedback

positive feedback system of enso

• El nino reduced ocean temp contrast reduces trade winds which increases El nino & so on

la nina

• trade winds extra strong

• more cold water upwelling in east pacific, higher pressure

  • colder and positive

• El nino 3.4 0.5 colder

sea water avg ph

8.1

how does ph change w/ depth?

surface is about 8.1, drops from 100-1000m from CO2 of animal respiration (since photosynthesis not happening so no counterbalence), then gradual increase after 1000m from carbonate buffering

carbonate buffering

CaCO₃ (from organisms) neutralizes acids, H2CO3 is also a buffer

thermocline

layer where water temp changes rapidly w/ depth, usually between 300 - 1000m

• greatest in low latitude and basically non-existent in high latitudes

  • highest impact on density

halocline

layer where water salinity changes rapidly w/ depth

• low impact except at poles (bc poles isothermal)

pressure effect on ocean

• density increases up to 5% bc of water

  • only significant in deep ocean

pynocline

layer where density changes rapidly with depth

• decreases with increasing latitude

AABW (antarctic bottom water)

densest cold and salty water forming bc ice formation makes seawater very salty, which makes it sink

• important in powering deep water circulation

north Atlantic deep water

second densest water from Greenland and sea sinking in the chimmenies,