marine bio test #1

what are the three layers of the earth?

core, mantle, crust (aka lithosphere) which is where plates are!

what are the two types of plates?

oceanic, which is made of basalt

continental, above ground and made of thicker granite

why do plates move?

plates move because of convection currents (hot air rises, cold air sinks, cycle repeat) as a result plates separate

3 boundary types

diverging/constructive - oceanic plates separate because of convection currents, new material from an underwater volcano fills the gap, creating a mountain

converging - oceanic plate and continental plate push together, oceanic plate is heavier and gets pushed under and melts

transform - two continental plates are sliding past each other

what is sediment?

accumulation of loose material (sand, mud, gravel, etc)

how do we measure the age of sediment

we use sediment cores (long cylinders of sediment brought up by ocean floor drilling) which can help us understand the earth’s past

lithogenous sediment

tells us about changing plate tectonic activity, come from erosion of rocks

typically accumlate along continental margins, but sometimes small particles move out to sea and form a sediment called abyssal clay

biogenous sediments

tell us about environmental conditions in ocean surface waters

made up of skeletal remains of once-living organisms, including shells of microscopic organisms (tests), coral fragments, etc.

includes ooze (separate flashcard)

hydrogenous sediment

give us substances for money, created from chemical reactions in seawater

evaporites: sediment that comes from evaporated seawater that crystalize and group together

manganese nodules: lumps of iron and manganese oxide all over the seafloor

what is ooze? what are the two types?

when tests make up more than 30% of the particles in a sediment, it is called an ooze, typically found in the open ocean

calcareous ooze: calcium carbonate, made of the tests of foraminifers and coccolithophores, harden into chalk as they get low into the ocean

siliceous ooze: made of radiolarians and diatoms, found in polar regions, and open ocean areas. sometimes, the silica that makes up siliceous ooze is combined with calcareous ooze to made hard lumps called chert nodules

what do grain size/rounding mean?

they indicate the energy of the environment in which they are from (applies best to lithogenous sediments). a beach is high energy, with big grains that become smooth, the ocean floor is the opposite

neritic vs pelagic

neritic — found close to land

pelagic — biogenous, found farther away (see image)

how does wave erosion work, what are some examples

• 

depositional features

• 

east coast vs west coast features

• The east coast has depositional features

  • Reason: east coast has sinking shoreline and a passive margin (no real activity happening except for sediment growth)

• The west coast has erosional features

  • Reason: west coast has rising shoreline, coast has subduction zones

lagoons

• Lagoons form when dunes separate water completely from the ocean

  

eustatic sea level change/sea level rise

• Eustatic sea level change: global changes to sea level (seen in the East Coast because the areas near the ocean are in danger of sinking because the sea levels are rising)

• What causes sea level to drop: expanding glaciers, cooling ocean temperatures, and increasing ocean basin size

• Sea level has increased a lot recently because of US!!!! Currently rate of sea level is 3.4 mm/yr

how do scientists gather data on past sea levels

deep-sea sediments, ice cores, coastal caves, and lagoon sediments

parts of a wave

wave orbins

basically, the object never really moves (in a perfect world) because the ENERGY is what’s moving

what causes waves?

wind

tides (caused by gravity)

tsunamis (tectonic activity causes them)

wind-specific waves

waves are affected by: wind strength, wind duration, and fetch

what is difference between seas and swells?

seas are where the generating force is, swells are where there is no generating force!

seas are super chaotic and diverse, swells are consistent and have long periods, fast

this is because of wave sorting. long periods have a greater speed so they move ahead of shorter waves (kind of like in a marathon)

wave orbits

waves transfer energy through orbits (little circles) which decrease as these go down

if orbits touch the bottom, you have a shallow water wave

the bottom of the wave orbits is the wave base, orbits reach depth of ½ wave length

so why do waves break?

crest is moving wayyy faster and it creates an angle

spilling breaker

shallow sloping/flat bottom

plunging breaker

steep bottom, quickly loses energy

surging breaker

steep bottom, abrupt shore

constructive vs destructive

refraction

reflection

diffraction

spread of wave energy sideways to the direction of wave travel, around/through an obstacle or gap