module 12: earths oceans

Question 1

how old is the earth?

Answer 1

radio active isotopes show that the earth is 4.6 billion years old

Question 2

earths water either originated from a ___ source or a ____ source

Answer 2

a remote source or local source

Question 3

oceans reached their present size about… (years ago)

Answer 3

4 million years ago

Question 4

oceans contain %? of the water found on earth and the other %? is frozen ice and fresh water

Answer 4

97% water found on earth, 3% frozen ice and freshwater

Question 5

3 major oceans -

Answer 5

pacific ocean, atlantic ocean, and indian ocean

Question 6

2 polar oceans -

Answer 6

artic ocean and southern ocean

Question 7

ocean water is made of (%)

Answer 7

96.5% pure water and 3.5% dissolved solids

Question 8

the 6 most abundant elements in ocean water -

Answer 8

chlorine, sodium, magnesium, sulfur. calcium, potassium

Question 9

salinity -

Answer 9

the measure of the amount of dissolved salts in seawater. (grams of salt per kilogram of ocean water / average salinity of oceans –> 35ppt (parts per thousand)

Question 10

density -

Answer 10

the ratio of the mass of a substance to the volume of the substance. effected by two factors - salinity and temperature

Question 11

pack ice -

Answer 11

a floating layer of sea ice that covers and area of the ocean surface. (as ocean water freezes)

Question 12

ocean color is determined by -

Answer 12

the way it absorbs/reflects sunlight.

Question 13

temperature profile -

Answer 13

plots changing ocean water temperature against depth. (varies between location and season)

Question 14

3 water masses -

Answer 14

antarctic bottom water, north atlantic deep water, antarctic intermediate water

Question 15

wave -

Answer 15

rhythmic movement that carries energy throughout matter or space (sometimes generated by wind)

Question 16

crest -

Answer 16

the highest point of the wave

Question 17

trough -

Answer 17

the lowest point of a wave

Question 18

wavelength -

Answer 18

the horizontal distance between 2 consecutive crests

Question 19

wave height -

Answer 19

the vertical distance between crest to trough

Question 20

wave height depends on these 3 factors -

Answer 20

fetch - the expanse of water that the wind blows across
wind duration - how long the wind blows uninterruptedly
wind speed - the faster the wind speed, the higher the waves

Question 21

breaker -

Answer 21

a foamy mass of water that collapses onto the coastline

Question 22

tide -

Answer 22

periodic rise and fall of sea level caused by the gravitational attraction among earth, the moon, and the sun

Question 23

tidal range -

Answer 23

the difference in water level between high and low tide

Question 24

daily tidal cycle (time)

Answer 24

24 hours and 50 minutes

Question 25

the 3 tidal cycles -

Answer 25

semi-diurnal cycle - 2 high tides each day
mixed tidal cycles - 1 pronounced and 1 smaller high tide daily
diurnal tidal cycle - 1 high tide each day

Question 26

spring tides -

Answer 26

during the new moon and full moon, the moon, earth, and sun and combined. this results with higher high tides and lower low tides (increase of the daily tidal range)

Question 27

neap tides -

Answer 27

during the first and third quarter phases of the moon, the moon and sun are at right angles in relation to earth. this results in higher low tides and lower high tides. (decreases daily tidal range)

Question 28

surface currents -

Answer 28

wind driven movement of ocean water that primarily affects the upper few hundred meters of the ocean. (driven by earths winds, can be influenced by land masses and coriolis effect)

Question 29

gyre -

Answer 29

closed circular ocean current systems

Question 30

5 major gyres -

Answer 30

north atlantic, north pacific, south-atlantic, south pacific, and indian ocean
(gyres in the N hemisphere move clockwise and gryes in the S hemisphere move counter clockwise)

Question 31

upwelling -

Answer 31

the upward motion of ocean water (cold and nutrient rich, typically seen off the western coasts of continents)

Question 32

density currents -

Answer 32

movement of ocean water that occurs in depths too great to be affected by surface winds (generated by differences in water temp and salinity/also known as deep ocean currents)

Question 33

shorelines are shaped by -

Answer 33

waves, tides, and currents

Question 34

beach -

Answer 34

area in which loose sediment is deposited and moved by waves along the shore

Question 35

wave refraction -

Answer 35

process in which waves advancing toward shore slow when they encounter shallow water causing the initially straight waves crests to bend toward the headlands

Question 36

longshore bar -

Answer 36

submerged sandbar located in the surf zone of most beaches (waves begin to break when they hit this)

Question 37

longshore current -

Answer 37

current that flows parrallel to the shore and moved large amounts of sediment

Question 38

rip current -

Answer 38

form when water from large breakers returns to the ocean through channels that cut through underwater longshore bars that are parallel to the beach

Question 39

spit -

Answer 39

a narrow bank of sand that projects into the water

Question 40

baymouth bar -

Answer 40

forms when a spit crosses a bay

Question 41

barrier island -

Answer 41

long ridges of sand separated from the mainland

Question 42

tombolo -

Answer 42

ridge of sand that connects an island to the mainland

Question 43

man made structures that are built to prevent beach erosion and destruction of oceanfront properties -

Answer 43

seawalls, groins, jetties, and break waters

Question 44

continental margin -

Answer 44

area where edges of continents meet the ocean (represents the shallowest part of the ocean - includes the continental shelf, slope and rise

Question 45

continental shelf -

Answer 45

shallowest part of a continental margin
(glacial periods - water level drops, most shelf is exposed, subject to being eroded. non - glacial periods - water level (higher) covers shelf

Question 46

continental slope -

Answer 46

sloping oceanic region found beyond the continental shelf that generally marks the end of the continental crust

Question 47

turbidity current -

Answer 47

rapidly flowing water currents along the bottom of sea that carries heavy loads of sediment

Question 48

continental rise -

Answer 48

gently sloping accumulation of deposits from turbidity currents that form at the base of the continental slope

Question 49

deep ocean basins -

Answer 49

broad, flat, abyssal plains, deep sea trenches, mid - ocean ridges, and submerged volcanoes

Question 50

abyssal plains -

Answer 50

a large, flat, almost level area of the deep - ocean basin where the ocean is 5 or 6 km deep. they cover about half of the deep ocean basin and are the flattest regions of earth. caused to be flat by layers of sediment

Question 51

trench -

Answer 51

a long, narrow, and steep depression, that forms on the ocean floor as a result of subduction of a tectonic plate. (volcanic mountain ranges and island arcs form near hear)

Question 52

mid - ocean - ridge -

Answer 52

chain of underwater mountains that run throughout the oceans basins (total length-65,000km, active and extinct volcanoes, averg. height of 1500m)

Question 53

hydrothermal vent -

Answer 53

a hole in the seafloor through which fluid heated by magma erupts. (located along the bottom of rifts in mid - ocean - ridges (many different minerals))

Question 54

seamounts -

Answer 54

submerged volcanic mountains that are taller than 1km (form in areas like hotspots)

Question 55

guyots -

Answer 55

former volcanic islands whose tops have been eroded flat by waves also called table mounts