MARN 1001 Exam 1

What is a divergent boundary

A plate boundary where two plates move away from each other

What is a convergent boundary

A plate boundary where two plates move toward each other

What is a transform boundary?

a place where two plates slip past each other, moving in opposite directions

What is a trailing margin?

a plate whose margin includes both land and sea, coast is not located on a boundary

Where on the US coastline does a convergent boundary occur?

On the west coast by Oregon and california and Alaska

Where on the US coastline does a divergent boundary occur?

Off the west coast by the Juan de Fuca plate

Where on the US coastline does a transform boundary occur?

Along the west coast

Where on the US coastline does a trailing margin occur?

East coast, gulf of Mexico coast, US arctic coast

How does boundary type affect shelf width?

On a trailing margin- wide shelf
On active, convergent boundaries- narrow shelf

isostatic adjustment

Concept of vertical movement of sections of Earth's crust to achieve balance or equilibrium

As a result of isostasy, what happens to a coastal mountain chain as it erodes?

As mountain chains erode, the added weight to the continental shelf will cause it to sink

As a result of isostasy, what happens to a shelf on a trailing margin as eroded material is added?

As a shelf sinks, it pulls the coast that is above water with it

Define tropical in terms of latitude

between 20° N and 20° S

Define temperate in terms of latitude

30-60° N and 30-50° S

What are 4 typical ecosystems that occur on a trailing margin?

1. Sandy beaches
-Constant sand movement
-Difficult for animals to build structures
2. Salt marshes
-Salt marshes occur in temperate regions
3. Mangals
-Mangals occur in tropical regions
4. Drowned river valleys
-Form when seawater fills coastal section of river valley

Describe shoreline-erosion distribution along US coasts and how it is related to shoreline type. Include the east coast, the west coast, the Gulf of Mexico and Alaska.

-East coast is more eroded than Pacific because the east coast has soft sand beaches and a sinking margin
-Gulf coast is sinking faster than the east coast because of heavy sediment deposit
-US Arctic coast is a passive margin and by far the fastest eroding of the US coastlines because of thawing permafrost and melted ice

As an estimate, how much shoreline erosion would be caused by a 1-inch sea level increase?

For every 1 inch in sea-surface level increase, erosion will take 100 inches

Define the term geological hotspot and give examples of coastal US areas formed by hotspots.

Hotspots are places on Earth with volcanic activity without being near plate boundaries. In an ocean hotspot, volcano can become tall enough to form an island
Hawaii, Galapagos and Iceland

What three things determine wave size?

1. Wind speed
2. Wind duration
3. Fetch

What is fetch?

the distance where the wind blows in a straight path

Define how wave height relates to wave energy and how wave energy affects erosion.

wave energy determines wave height and the more the wave will erode from the surface

Define how wave length determines wave speed in the open ocean.

In the open ocean, wave speed is determined by wavelength. The longer the wavelength, the higher the speed

In which direction do hurricanes rotate in the northern hemisphere?

counter clockwise

How do waves bend when approaching a headland vs. when approaching a bay?

Headland- refract
Bay- wave energy dispersed (high to low energy and sediment deposit)

When a wave is approaching a headland, is the wave energy concentrated or spread out?

concentrated

When a wave is approaching a bay, is the wave energy concentrated or spread out?

spread out

When a wave is approaching a headland, is it a high-energy environment or low-energy?

high energy

When a wave is approaching a bay, is it a high-energy environment or low-energy?

low energy

How is longshore transport formed?

when waves hit (go in) at an angle but water and suspended particles return straight down the shore

What does the longshore transport carry?

water and suspended particles

What are the three parts of a drift sector?

1. Starting point (where sediment is eroded (cliff) from high wave energy --> more sand lost than gained)
2. Equilibrium (where there is long shore transport)
3. End point (sediment is deposited where there is low wave energy --> more sand gained than lost)

What happens to the sand when there is no low-energy environment for sand deposition?

Will either go out to shore or settle and then add up weight and then landslide and settle into deep submarine basin

What creates tides?

when the gravities of the Sun and Moon pull on Earth's oceans

Why does the moon have a larger effect on tides than the sun?

role because the Moon is so much closer than the Sun

What are the three types of tides?

diurnal, semidiurnal, mixed

What is a diurnal tide?

has one high and one low in one tidal day

What is a semidiurnal tide?

two high tides and two low tides each day

What is a semidiurnal mixed tide?

two highs and two lows in a tidal day, but the highs and lows are always of different heights (high high, low high, low low, and high high)

What is a high tide?

the state of the tide when at its highest level.

What is a low tide?

the state of the tide when at its lowest level.

What is the most common tide type globally?

semidiurnal

How does the Coriolis effect affect large-scale movement in the Northern versus Southern hemisphere?

Northern hemisphere- causes large scale movement to deviate to the right of initial movement
Southern Hemisphere- causes large scale movement to deviate to the left of the initial movement

How do variations in water height occur during a tide?

Low high tide is hidden from the gravitational pull of the moon
High tide points toward the moon and away from the moon
Low tides are a quarter turns away from high tides

Explain the tidal day (duration)

24 hours and 50 minutes because the moon is moving as the earth is turning

How do neap tides occur?

When the Moon is in the first quarter and in the third quarter, the Sun is at a 90° angle with the Moon, and the Sun's gravity will counteract the Moon gravity, causing very small tides.
The tidal range (difference between high and low tide) is the largest

How do spring tides occur?

Twice a month, at new and full moon when sun moon and earth are lined up, the combined effect of moon and sun results in extra large tides
The tidal range (difference between high and low tide) is the largest

How does air pressure cause deviations from predicted tidal height?

With every 1 mbar pressure change, the sea-surface level changes 1 cm

What are amphidromic points in relation to tides?

The center that tides rotate around due to Coriolis affect and the tidal wave

How do amphidromic points affect tidal height?

Since they are the lowest point of the tide, the farther away from point, the larger the tidal range

What is a micro-tidal coast?

Have tidal ranges less than 2 m and typically occur on open ocean coasts

What is a meso-tidal coast?

Have tidal ranges of 2-4 m
most of Malaysia and Indonesia, and the African east coast.

What is macro-tidal?

Have tidal ranges larger than 4 m and only occur where the continental shelf is wide or where the coast amplifies the tidal range

What is tide?

the daily rise and fall of sea level

What is a wave-dominated coast?

If the coast is wave-dominated, waves cause most erosion, transport and deposition processes

What is the difference between high tide and flooding tide?

High tide is one time point
Flooding time is the time period when water level is increasing

What is the difference between low tide and ebbing tide?

Low tide is one time point
Ebbing tide is the time period when water level is decreasing

When do the fastest and slowest tidal currents occur?

Fastest- between high and low tide
Slowest- closer to high and low tide (0 at high or low --> slack water)

How do faster and slower and tidal currents relate to erosion?

The speed of the current determines how much material the current can carry

What is an asymmetric tide?

Have flooding and ebbing tide of different lengths of time, however both have to move same amount of water => shorter tide has to be faster

How do asymmetric tides effect sediment movement?

because one tide is faster than the other, it can carry more sediment than the slower, longer tide

What does intertidal mean?

the area between the high tide and low tide mark where the tide supplies food and where most organisms live

What is nekton?

free-living, water-column organisms, whose motion are independent of current

What is plankton?

small organisms that originally were thought to have no ability to move against currents, however can control their own motion

What is benthos?

organisms that live on the ocean floor

What is phytoplankton?

plankton consisting of microscopic plants

What is zooplankton?

plankton consisting of microscopic animals

What is epifauna?

benthos that live on the substrate (rock, sand, mud)

What is infauna?

benthos that live in the substrate

What is mutualism?

both organisms benefit

What is commensalism?

one organism benefits and the other is unaffected

What is parasitism?

one species benefits and the other is harmed

What is an apex predator?

predator at the top of the food chain

What is a key stone species?

presence greatly affects other local species

What is a trophic pyramid?

Models that show how energy flows through an ecosystem

What types of organisms occur at each level of a trophic pyramid?

Level 1- primary producer
Level 2- herbivorous consumers
Level 3- first-level carnivorous consumers
Level 4- second-level carnivorous consumers
Level 5- third-level carnivorous consumers

How does a trophic pyramid differ from a food web?

Trophic pyramid follows one line of energy, food web follows multiple

Is a trophic pyramid or a food web more realistic?

Food web

Which compounds are consumed in primary production?

CO2 and nutrients

Which compounds are produced in primary production?

O2 and organic material

Which compounds are consumed in respiration?

O2 and organic material

Which compounds are produced in respiration?

CO2 and nutrients

What does nutrient mean in marine science?

inorganic materials

What are the two main limiting factors for primary production?

light and inorganic nutrients

Name the three main nutrients in seawater.

co2, o2, and nitrate

What is a macronutrient and what are 2 examples?

A nutrient that is required in significant amounts in the diet
-nitrate and phosphorus

What is a euphotic zone?

The zone where there is enough light to support photosynthesis

What is the difference between euphotic zone depth in the coastal ocean versus the open ocean?

The euphotic zone is shallower in the coastal ocean (especially estuaries ) than in the open ocean

What is compensation depth?

depth where there is as much oxygen produced by photosynthesis as consumed by respiration

Which light wavelengths are not absorbed well by water?

middle 350-550

Give three examples of pigments and describe which wavelengths they absorb.

1. chlorophyll can absorb two wavelength ranges of light very well at ~ 420 nm (violet light) and a second at ~670 nm (orange light)
2. fucoxanthin- 5-550
3. phycoerythrin- 450-480

Describe light variation with latitude

The intensity of solar radiation at middle latitudes between about 40° and 60°N & S is highly variable annually. This is because the angle of the sun's rays reaching the surface is highly variable at these latitudes.

What is the Redfield ratio?

All photosynthetically produced organic material has the Redfield ratio:
106 carbon atoms : 16 N atoms : 1 P atom

C:N:P 106:16:1

What is ecosystem service?

a benefit derived from the ecosystem

What are the four main groups of ecosystem service?

1. provisions
-food
2. Regulating the environment
-keeping water clean
-preventing erosion
3. Cultural services
-recreation
-beauty
-human
4. Support for itself or other ecosystems
-cycling nutrients

What is the Keeling Curve?

a graph which plots the ongoing change in concentration of carbon dioxide in Earth's atmosphere since 1958

What is the current trend of the Keeling Curve?

the average increase in concentration is about 3 ppm per year

Why does the Keeling Curve have a zig-zag pattern?

by seasonal variations in CO2 concentration
-Plants take up more CO2 for photosynthesis in spring and summer, and release more CO2 through respiration in fall and winter (productive season)

Where are measurements collected for the Keeling Curve?

Mauna Loa Hawaii

What is the correlation between carbon dioxide concentrations and temperature during the past 160,000 years?

Has a positive correlation

What is remarkable about the current carbon dioxide concentration range and trend?

That it keeps increasing!