module 12: earths oceans Flashcards
how old is the earth?
radio active isotopes show that the earth is 4.6 billion years old
earths water either originated from a ___ source or a ____ source
a remote source or local source
oceans reached their present size about… (years ago)
4 million years ago
oceans contain %? of the water found on earth and the other %? is frozen ice and fresh water
97% water found on earth, 3% frozen ice and freshwater
3 major oceans -
pacific ocean, atlantic ocean, and indian ocean
2 polar oceans -
artic ocean and southern ocean
ocean water is made of (%)
96.5% pure water and 3.5% dissolved solids
the 6 most abundant elements in ocean water -
chlorine, sodium, magnesium, sulfur. calcium, potassium
salinity -
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)
density -
the ratio of the mass of a substance to the volume of the substance. effected by two factors - salinity and temperature
pack ice -
a floating layer of sea ice that covers and area of the ocean surface. (as ocean water freezes)
ocean color is determined by -
the way it absorbs/reflects sunlight.
temperature profile -
plots changing ocean water temperature against depth. (varies between location and season)
3 water masses -
antarctic bottom water, north atlantic deep water, antarctic intermediate water
wave -
rhythmic movement that carries energy throughout matter or space (sometimes generated by wind)
crest -
the highest point of the wave
trough -
the lowest point of a wave
wavelength -
the horizontal distance between 2 consecutive crests
wave height -
the vertical distance between crest to trough
wave height depends on these 3 factors -
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
breaker -
a foamy mass of water that collapses onto the coastline
tide -
periodic rise and fall of sea level caused by the gravitational attraction among earth, the moon, and the sun
tidal range -
the difference in water level between high and low tide
daily tidal cycle (time)
24 hours and 50 minutes
the 3 tidal cycles -
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
spring tides -
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)
neap tides -
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)
surface currents -
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)
gyre -
closed circular ocean current systems
5 major gyres -
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)
upwelling -
the upward motion of ocean water (cold and nutrient rich, typically seen off the western coasts of continents)
density currents -
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)
shorelines are shaped by -
waves, tides, and currents
beach -
area in which loose sediment is deposited and moved by waves along the shore
wave refraction -
process in which waves advancing toward shore slow when they encounter shallow water causing the initially straight waves crests to bend toward the headlands
longshore bar -
submerged sandbar located in the surf zone of most beaches (waves begin to break when they hit this)
longshore current -
current that flows parrallel to the shore and moved large amounts of sediment
rip current -
form when water from large breakers returns to the ocean through channels that cut through underwater longshore bars that are parallel to the beach
spit -
a narrow bank of sand that projects into the water
baymouth bar -
forms when a spit crosses a bay
barrier island -
long ridges of sand separated from the mainland
tombolo -
ridge of sand that connects an island to the mainland
man made structures that are built to prevent beach erosion and destruction of oceanfront properties -
seawalls, groins, jetties, and break waters
continental margin -
area where edges of continents meet the ocean (represents the shallowest part of the ocean - includes the continental shelf, slope and rise
continental shelf -
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
continental slope -
sloping oceanic region found beyond the continental shelf that generally marks the end of the continental crust
turbidity current -
rapidly flowing water currents along the bottom of sea that carries heavy loads of sediment
continental rise -
gently sloping accumulation of deposits from turbidity currents that form at the base of the continental slope
deep ocean basins -
broad, flat, abyssal plains, deep sea trenches, mid - ocean ridges, and submerged volcanoes
abyssal plains -
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
trench -
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)
mid - ocean - ridge -
chain of underwater mountains that run throughout the oceans basins (total length-65,000km, active and extinct volcanoes, averg. height of 1500m)
hydrothermal vent -
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))
seamounts -
submerged volcanic mountains that are taller than 1km (form in areas like hotspots)
guyots -
former volcanic islands whose tops have been eroded flat by waves also called table mounts
