Oc Midterm 2

Front 1

Tides are created by

Back 1

imbalances between:

1. GRAVITATIONAL FORCE

2. CENTIFUGAL (center-fleeing) FORCE

Front 2

newton's law of gravitation

Back 2

attractive gravitational force is directly proportional to the product of the masses (m1 & m2)

and INVERSELY proportional to the distance (squared) between the masses
(R)

Fg = G(m1m2) / R^2

G = 6.672x10^-11 Nm^2kg^-2

Front 3

gravitational forces on earth causing tides are DUE TO

Back 3

THE MOON

Front 4

gravitational force due to the moon is directed toward..

Back 4

the moon's center of mass

Front 5

gravitational force due to the moon decreases with..

Back 5

increasing distance


ie side of earth furthest from moon receives least g force

Front 6

centrifugal forces on earth are due to

Back 6

THE MOON

Front 7

centrifugal force due to moon

-- distribution of force on earth

Back 7

evenly distributed
(same everywhere)

Front 8

two forces causing tides due to moon
--- rel. distribution on earth

Back 8

gravitational
--decreases with increasing distance

centrifugal:
--same everywhere

Front 9

centrifugal force on earth due to moon is directed..

Back 9

perpendicular to earth's axis
everywhere on earth

Front 10

resultant forces

(due to centrifugal and graviational due to moon)

Back 10

= the difference between gravitational (G)
and centrifugal (C) forces

Front 11

(forces due to moon)

resultant forces are _____ on side of earth opposite of moon

Back 11

directed AWAY from moon

Front 12

(forces due to moon)

resultant forces are _____ on side of earth closest to moon

Back 12

directed TOWARD moon

Front 13

"resultant forces"

are not the same as

"tide generating forces"

Back 13

tide generating forces (Ft)
are the HORIZONTAL component of the resultant forces

Front 14

tide generating forces create _#_ bulges...:

Back 14

2 bulges:

1. away from moon on side of earth opposite moon

2. toward moon on side of earth facing moon

Front 15

earth rotates (tidal bulges)

Back 15

earth rotates into and out of tidal bulges
--> CREATES HIGH AND LOW TIDES

Front 16

the lunar day

Back 16

50 min longer than the solar day

(bc moon is moving in its orbit AROUND EARTH)

Front 17

tidal bulges follow..

Back 17

moon as it rotates around earth

Front 18

SOLAR bulges

Back 18

46% the size of lunar bulges

--even tho sun more massive, MUCH FARTHER

Front 19

spring tide

Back 19

moon alligned with earth and sun
--ie E-M-S system alligned
"SYZYGY"
(when new moon / full moon)

**Lunar & solar bulges = CONSTRUCTIVE:
--large tidal range

Front 20

neap tide

Back 20

moon not alligned with E and sun
---ie E-M-S system at right angles
"QUADRATURE"
(1st quarter moon, 3rd quarter moon)

**Lunar & solar bulges DESTRUCTIVEly interfere
--small tidal range

Front 21

monthly tidal cycle

Back 21

every 7 days earth alternates between
SPRING TIDE
&
NEAP TIDE

Front 22

"syzygy"

Back 22

allignment E-M-S

(constructive bulges)

Front 23

"quadrature"

Back 23

E-M-S at rt angles

(bulges destructively interfere)

Front 24

monthly tidal cycle __#__ days

Back 24

29

Front 25

"effect of declination" (Moon, Earth / tides)

Back 25

Plane of moon's orbit tilted
5*

w/ respect to the ecliptic (tilt of earth rotation w/i orbit)

Front 26

moon's precession

Back 26

the moon's elliptical orbit itself PRECESSES....
ie the orbit rotates

precesses over 18.6 years

max declination ranges from: 18.4* to 28.4*

Front 27

moon's precession takes __ years

Back 27

18.6

Front 28

max declination of moon (range) in precession

Back 28

18.4* to 28.4

Front 29

equilibrium theory of tides

(idealized earth)

Back 29

(most) locations have TWO high tides AND TWO low tides / day

the two high tides aren't the same height
the two low tides aren't the same height
(due to declination of moon and sun)

yearly and monthly cycles of tidal range are related to changing distances of M and S (from earth)

each week there would be alternatiing spring and neap tides

Front 30

"cotidal lines"

Back 30

lines showing where the tide will be high at the same time

(lines drawn by radiating from amphidromic points (pts of no motion))

Front 31

"amphidromic points"

(from dynamic {real} theory of tides)

Back 31

a point of "no motion" a tidal wave revolves around

-ocean breaks into smaller cells where tide waves revolve around 15 pts of "no motion"

** 7 in Pacific

** 4 in Atlantic

** 4 in Indian

Front 32

tides in a basin

Back 32

tidal range is determined by basin configuration

Front 33

tides in NARROW basin

Back 33

true amphidromic system does not develop

--bc space for rotation not available

Front 34

tidal energy is dissapated...

Back 34

along the coastline
& w/i the deep ocean

Front 35

cotidal map

Back 35

shows tides rotate around amphidromic pts

--map w/ cotidal lines drawn on

Front 36

tides can be confined by

Back 36

basin configuration

Front 37

tides in narrow basin

Back 37

true amphidromic system doesnt develop -- space for rotation not available

Front 38

3 types of tidal patterns

Back 38

1. DIURNAL
-1 hi, 1 lo tide / lunar day

2. SEMI-DIURNAL
-2 hi, 2 lo tides / day (of abt same height)

3. MIXED
-characteristics of diurnal and semi-dirunal
-successive hi &/or lo tides have sig. diff heights

Front 39

world's largest tidal range (where?)
(why?)

Back 39

Bay of FUndy

-tidal energy is FOCUSED
(due to shape of bay / shallowness)

-max spring tidal range = 17 m

Front 40

tidal currents occur...

Back 40

in some bays / rivers due to a change in tides

EBB currents (due to outgoing tides)

FLOOD currents (due to incoming tides)

Front 41

"tidal bore"

Back 41

"a true tidal wave"

-- WALL of water that moves UP-RIVER

-caused by incoming hi tide

-- occurs in some lo lying rivers

(can be large enough to surf / raft)

Front 42

storm surge tide

Back 42

observed tide due to storm

storm surge = the height of the observed storm wave above what the 'predicted' tide height is

Front 43

"tides"

Back 43

long period gravitational waves balanced by centripetal force

Front 44

"planetary orbital theory"

Back 44

equilibrium theory

(opposed to dynamic theory)

Front 45

dynamic theory of tides takes into account..

Back 45

tides are forced waves
due to:

1. OCEAN DEPTH
2. CONTINENT PLACEMENT

-->
--> LIMITING tidal speed to ~ 230m/s in open ocean

Front 46

waves are created by

Back 46

releases of energy
(IE DISTURBANCES)

-wind

-diff. density fluids moving

-mass movement into ocean ("SPLASH WAVES")

-underwater seafloor movement
("TSUNAMI")

-"TIDES" (pull of moon / sun)

-human activities

Front 47

waves transmit

Back 47

ENERGY

(NOT mass)

across ocean surface

Front 48

wave behavior depends on

Back 48

1. wave SIZE

2. h2o DEPTH

Front 49

"wind waves"

Back 49

energy transferred from wind to water

Front 50

waves can change direction by:

Back 50

1. REFRACTION

2. DIFFRACTION

3. REFLECT FROM SOLID OBJECTS

4. INTERFERE W/ OTHER WAVES

Front 51

"free waves"

Back 51

move independently of generating force

(ie WIND WAVES)

Front 52

when disturbing force causing wave is applied CONTINUOUSLY,

Back 52

wave is a

"FORCED WAVE"

(tides)

Front 53

"orbital waves"

Back 53

= a type of progressive wave

Front 54

"progressive waves"

Back 54

waves of moving energy
travelling in ONE direction along a surface
where particles of water move in CLOSED CIRCLES as the h2o passes

(ex = orbital wave)

Front 55

"capillary waves"

Back 55

-height < 1.7 cm

-primary restoring force = SURFACE TENSION

Front 56

"gravity waves"

Back 56

-height > 1.7 cm

-primary restoring force = GRAVITY

*** WIND WAVES*** are gravity waves formed by transfer of wind energy to h2o
--wind forces convert capillary waves --> wind (gravity) waves

Front 57

wind forces convert...
(waves)

Back 57

cappilary waves
to
wind
(ie gravity)
waves

Front 58

"fully developed sea"

Back 58

max height of waves produced by conditions of:
wind speed / duration / fetch

Front 59

"swell"

Back 59

waves that have travelled out of the fetch area
& exhibit uniform / symmetrical shape

Front 60

factors affecting wind wave development
(4)

Back 60

1. WIND STRENGTH
-wind speed must be faster than wave crests
(for energy transfer to cont.)

2. WIND DURATION
-winds that blow for a SHORT time will NOT generate large waves

3. FETCH


4. SWELLS
-travel faster than the wind "outside" the sea

Front 61

WIND STRENGTH

(factors affecting wind wave development)

Back 61

wind speed must be faster than wave crests

(for energy transfer to continue)

Front 62

WIND DURATION

(factors affecting wind wave development)

Back 62

winds that blow for short time
will NOT MAKE LARGE WAVES

Front 63

FETCH

(factors affecting wind wave development)

Back 63

the uninterrupted distance over which a wind blows
W/O changing direction

Front 64

SWELLS

(factors affecting wind wave development)

Back 64

travel faster than the wind,
outside the "sea"

--lose little energy while travelling over ocean surface

Front 65

when waves from different storm systems exist simultaneously
(3)

Back 65

1. DESTRUCTIVE interference
-2 waves cancel eachother out
= reduced wave / no wave

2. CONTRUCTIVE interference
"additive interference"
= waves larger than the original waves

3. ROGUE WAVES
-happen due to interference
= wave crest HIGHER THAN THEORETICAL MAXIMUM

Front 66

diff ways waves break against shore:
(3)

Back 66

1. SPILLING WAVES

2. PLUNGING WAVES

3. SURGING BREAKERS

Front 67

spilling waves

(way waves break on shore)

Back 67

crest of wave sLIDES down face of wave as it breaks on shore

FORMED FROM
-gradually sloping ocean bottoms

Front 68

plunging waves

(way waves break on shore)

Back 68

-break violently on shore

-leave air-filled tube (channel)
between crest and wave foot

FORMED WHEN
-waves approach a shore over steeply sloped botttom

Front 69

SURGING BREAKERS

(way waves break on shore)

Back 69

FORMED WHEN
-abrubt beach slope

--> causes waves to build up and break rapidly on shore

Front 70

wave refraction

(as wave approaches shore)

Back 70

when wave approaches shore:
--the part of the wave in shallow water slows
... part of wave in deep h2o continues at original speed
--> causing wave crests to refract (bend)


--results in waves lining up ~ parallel to shore

--wave energy is concentrated at headlands and dispersed in bays

Front 71

wave energy is REFLECTED when...

Back 71

(ie bounced back..)

when waves hits a solid obj.

Front 72

distribution of global water runoff
is
proportional to...

Back 72

total dissolved flux

--is proportional to

global sediment flux

(land-->ocean)

Front 73

aeolian transport

Back 73

areas where prevailingi winds are strongest (land->ocean)

= greatest quartz concentration in ocean

Front 74

4 main types of sediment

Back 74

1. LITHOGENIC
= sediment material
(fragments of pre-existing rock)

2. BIOGENIC
= hard remains of once-living org's (ie shell material)

3. HYDROGENIC
= chemical precipitate of dissolved material

4. COSMOGENIC
= from outerspace
(ie meteorite material)

Front 75

lithogenic sediment

(forms by)

[3]

Back 75

**lithogenic = fragments of pre-existing rock**

1. WEATHERING
of exposed rock

2. TRANSPORTATION
of sediment

3. DEPOSITION
thru settling / accumulation

Front 76

means of sediment delivery to oceans

(4)

Back 76

1. RIVERS
20.0 BT/yr

2. GLACIERS
2 BT/yr

3. WIND
0.7 BT/yr

4. COASTAL EROSION
0.4 BT/yr

Front 77

lithogenic sediment occurs as:

[2]

Back 77

1. NERITIC DEPOSITS
(near shore)
-beaches -continental shelves -turbidites -glacial rafted debris


2. PELAGIC DEPOSITS
(deep ocean floor)
---Abyssal clay

Front 78

"architectural development of COASTAL SYSTEMS"

5 major processes:

Back 78

1. RIVER DISCHARGE

2. SEDIMENT FLUX ACROSS DELTA PLANE

3. DISPERSION OF SEDIMENT BY PLUMES

4. SEAFLOOR/SHORELINE REWORKING BY WAVES/TIDES
in alongshore and offshore direction

5. MODIFICATION OF ACCOMODATION SPACE
by compaction -subsistence -isostacy

Front 79

most lithogenic sediment composed of:

Back 79

QUARTZ

--abundant
--chemically stable
--durable

Front 80

current strength v sediment transport

Back 80

weaker currents can move small particles

strong currents needed to erode larger sediment

Front 81

origin of biogenous sediment

Back 81

organisms that produce hard parts die

material rains down on ocean floor and accumulates as:
---MACROscopic shells/bones/teeth
(can see)

--MICROscopic tests (shells

**if comprised of >/=30% test material ="biogenous ooze"

Front 82

"biogenous ooze"

Back 82

sediment composed of at least 30% test material
(microscopic shells)

Front 83

biogenous tests
(microscopic)

composed of

Back 83

silica
(diatoms/algae)

CaCO3 (calcium carbonate)
(algae/protozoans)

Front 84

sediment composed of >30% silica test material

Back 84

"siliceous test material"

== SILICEOUS OOZE

Front 85

Siliceous ooze found...

Back 85

where it accumulates faster than it dissolves

(dissolves slowly but steadily)

high productivity = many silica tests sinking = siliceous tests accumulate on ocean bottom = siliceous ooze

Front 86

CaCO3 organisms

Back 86

cocolithophores
(algae)

foraminifors
(protozoan)

Front 87

calcarious ooze

Back 87

> 50% calcarious test material
ie caco3 tests

Front 88

calcite dissolves...

Back 88

beneath calcite compensation depth
"CCD"
1-4.5km

Front 89

most biogenic ooze found as

Back 89

pelagic deposits

Front 90

factors affecting dist of biogenous ooze

Back 90

1. productivity
(amt of org's in surface waters)

2. destruction
(dissolving at depth)

3. dilution
(mixing with lithogenous clays)

Front 91

origin of hydrogenous sediment

Back 91

--forms when dissolved materials come out of solution
(precipitate)

precipitation caused by:
-CHANGE in TEMP
-CHANGE in PRESSURE
-Addition of Chemically active fluids

Front 92

types of hydrogenous sediment

Back 92

1. manganese nodules

2. phosphates

3. carbonates

4. metal sulfides

5. evaporite salts

Front 93

cosmogenous sediment
(2 types)

Back 93

Microscopic space dust
Macroscopic meteor debris

Front 94

isostatic loads

Back 94

sig. load changes to a region's crust

sediment + water + ice sheets

Front 95

subsidence

Back 95

function of isostatic load changes
(water / ice / sediment)
&
eustatic volume changes
(ice sheet growth/melt)
&
compaction
&
human activities
&
flexural response
(ie time delay)

Front 96

"continental shelves"

Back 96

areas of submerged continental crust
that has been
STRETCHED OR THINNED

due to
-sea floor spreading
-tectonics

(has subsided isostatically)

most bounded on one side by land -- other by ocean

passive margins = broad
active seismic margins = narrow

Front 97

continental shelf formation

Back 97

accumulations of sediments eroed from adjacent land jand deposited on the thin ()stretched) cont. crust bordering them

Front 98

imp factors controlling sediment supply

Back 98

climate (latitude)

topography

Front 99

phyical weathering
/chemical weathering

dominant?

Back 99

chemical = low / tropical lat (hot humid)

physical = hi lat hi alt

Front 100

where does sediment end up

Back 100

dissolved material
-dispersed ocean wide

solid products of erosion
-coastal regions
-on continental shelves

sediment supply via ice
-thru ice / glaciers entering ocean
-only high lat
-antarctica = 95% supply (dep near coast)

wind blown
-dist world wide
(originates in subtropics where trade winds blow off cont. desert)

Front 101

turbidity currents

Back 101

= dense mix of sediment and water .. can trael down cont slope and slide across ocean floor

**contributes layers of turbidite deposits

when sediments accumulating near shelf break are destabalized -- & collapse / slide into ocean

Front 102

continental rise

Back 102

at base of cont. slope

turbidite deposits interlayed with pelagic sediments

Front 103

abyssal plains

Back 103

cover large areas of deep sea bed

--FLAT

-turbidity currents contribute

Front 104

dominant source sediment to oceans

Back 104

rivers

--NOT evenly dist around ocean margins

Front 105

short term (local) sediment variations

Back 105

seasonal / diurnal time scale

storms floods droughts

human activity (deforestation...

Front 106

longer term (global) sediment variation

Back 106

global climate changes = dominant controls on weathering / erosion rates

alternating transgressions / regressions of sea over the cont shelves exposed them to alt periods of submergnece and subaerial and glacial erosion
----- coastal enviros migrate back and forth across them

Front 107

glacial maxima (and sediment)

Back 107

sea level 100 m below present level

= coastal sediments deposited near shelf edge

= INCREASE freq turbidity currents
+ rate of sedimentation on continental rises & in deep sea

Front 108

relict sediments

Back 108

--terrestrial deposites remaining on shelves, below sea level

after ice melted -- sea level above shelves again

the residual deposits (gravel) couldntt be moved by waves

Front 109

shelf sea lifetime

Back 109

not permanent
-advance / retraeat on time scale of sea level chnages

(SHALLOW WATER ENVIROS ARE TRNASIENT)

Front 110

4 modes of sediment transport in WATER

Back 110

"BEDLOAD":
1. SLIDING
-continuous contact w bed
*Slow flows
2. ROLLING
-continuous contact w bed
*slow flows
3. SALTATION
-jump along bed
*fast flows


"SUSPENDED LOAD"
4. SUSPENSION
-irreg paths within water - seldom contact with bed until deposited when flow speed decreases
*FAST flows

Front 111

"boundary layer"

Back 111

region of water flow influenced by crust's surface
--slowed down by friction along boundary ("current shear")

--b-layer develops wherever fluid movesj across surface

**WATER IN DIRECT CONTACT WITH BED = STATIONARY (assuming no sediment moving)
**successive layers of water move faster with INCREASING DISTANCE from bed (and friction effects decrease

Front 112

'velocity shear'

Back 112

change of velocity w depth (velocity gradient)

... flow velocity increases with increasing distance from bed

RATE of speed increase gradually lessens with increasing distance

Front 113

'shear stress'

Back 113

-frictional force due to layer above

layer above moving faster, dragging along layer below
layer below moves more slowly and tends to drag above layer back

Front 114

shear stress proportional to

Back 114

speed of flow ^2

Front 115

boundary layer flow type

Back 115

1. laminar
(uncommon, can occur close to a boundary
or
2. tubulent

Front 116

most erosion and deposition of sediment takes place in...

Back 116

benthic boundary layer
(adjacent to sea bed)

... can be 10s meters thick
... so in shallow water can occupy entire water column

Front 117

extent sediment movement takes place... depends on....


(+ controls deposition bc control when particles sink

Back 117

1. degree of turbulence
(turbulent flow = greater frictional interaction w bed)

2. current shear
(rate change of currents VELOCITY with depth)
--> determines Shear Stress

3. rel. densities (the contrast) between sediment particles and water

4. water viscocity

5. laminar / turbulent flow