EPS SCI 15 Lab Final (extensive)

On a bathymetry map, the countours are lines of constant

depth

Lines of _____ are measured from 0-90 degrees north and south of the equator

latitude

On a bathymetry map, Vs that point UPHILL are

troughs (canyons)

On a bathymetry map, Vs that point DOWNHILL are

ridges

Vertical exaggeration calculation:

vertical scale over horizontal scale (distance on map / distance on earth)

Mass

density*volume

Atlantic style margins differ from Pacific style margins in that

pacific margins contain an oceanic trench instead of continental rise

What is the density of the continental crust (granite)?

2.7 g/cm^3

What is the density of the oceanic crust (basalt)?

3.0 g/cm^3

What is the density of the mantle?

3.3 g/cm^3

Mid-ocean ridges are frequently offset by perpendicular

fracture zones

Amongst ice, basalt, and granite, which is the least dense?

ice

The Archimedes' principle states that a rigid object displaces its full _______ when floating in a fluid.

weight

From the shoreline to the deep-ocean floor, what is the order of continental margins (shelf, slope and rise)?

shelf, slope, rise

What is the shelf break?

separation of the shelf and slope

Where does seafloor formation (new lithospheric material) occur?

mid-ocean ridges (moving outward)

Where is lithospheric material destroyed?

subduction zones
(dense oceanic tectonic plate bends and sinks beneath another plate into the Earth's mantle causing destroying and recycling of old lithosphere)

Spreading rate calculation:

distance / time (cm/yrs)

I.e. 400km = 400,000m = 40,000,000cm

→ 40,000,000cm / 15,000,000yr = 2.67 cm/yr

Where would you expect to find highest heat flow?

mid-ocean ridge

What is an example of a divergent plate boundary?

mid-ocean ridge

Where would you expect to find the most tectonic activity?

convergent boundary

What is an example of a convergent plate boundary?

subduction zone

Where would you expect to find the lowest heat flow?

subduction zone

Where would you find the least tectonic activity?

intraplate region

Which of the following sediments dissolve BELOW the carbonate compensation depth (CCD)?

calcareous oozes (CaCO3)

The CCD is ______ in cooler, more acidic waters at high latitudes

shallower

The CCD is _______ in warmer, less acidic waters at lower latitudes

deepest

Meteoroid dust is an example of ____ sediment

cosmogenous

Silt is an example of ____ sediment

terrigenous

Manganese Nodule is an example of _____ sediment

chemogenic

Foraminiferan Ooze is an example of ____ sediment

biogenic

Sedimentation rate calculation

mm / years

Where does most sediment accumulation occur?

around continents (much less accumulation happens in the deep sea)

What is the typical pH of seawater?

8

Residence time calculation:

amount of given element dissolved in ocean / the flux of the element in or out of the ocean

(i.e. 400g / 10g/yr = 40 yrs)

At which temperature does pure water reach its highest density?

4 degrees C

One consequence of hydrogen bonding in water:

high latent heat, high heat capacity, high melting point, high boiling point, less dense as a solid, etc.

Density of seawater increases when temperature

decreases

Which processes increase salinity of seawater?

freezing and evaporation

Which processes decrease salinity of seawater?

ice melting and precipitation

What is the average salinity of seawater?

34.7 PSU (~35)

What is one source of deep water?

North Atlantic Deep Water (and Antarctic Deep Water)

Surface currents are driven by

wind

The deflection of the intended path of a moving body by the Earth's rotation is the

Coriolis Effect

The surface and deep ocean are separated by which layer? What causes this separation?

Thermocline (change in temperature creates a change in density; more dense water sinks below less dense water)

Which plankton contributes to siliceous ooze production?

Diatom (phytoplankton)

Which plankton lives in chambered CaCO3 shells?

Foraminifera (zooplankton)

Which plankton is a minute crustacean with a chitin exoskeleton?

Copepod (zooplankton)

Which plankton makes up 50% of photosynthetic biomass?

Cyanobacterium (phytoplankton)

Types of macroplankton

krill, pteropods, gelatinous plankton (jellyfish)

Ratio of C:N:P

106:16:1

Cross sections provide a ____ view of earth

Side

Contour lines will never do what?

cross each other

Rapid change in elevation on bathymetric map.. contours would be spaced

closer together

What do concentric circles of counter lines represent?

mountains or valleys

What does the theory of isostasy suggest?

blocks of rigid lithosphere are floating = isostatic equilibrium on the plastic asthenosphere (region of earth's mantle)

What is the chemical composition of the Earth? (from inside to outside)

core, mantle, crust

What is the lithosphere?

cool rigid outer layer (crust and upper mantle)

What is the asthenosphere?

plastic part of mantle below lithosphere

What is the mesosphere?

middle and lower mantle, stronger plastic than asthenosphere

Passive (Atlantic) Margins

no plate boundary, low tectonic activity

Active (Pacific) Margins

high tectonic activity, abrupt transition to trench, absent continental rise

What are abyssal plains?

flat areas of deep ocean floor (flattest/smoothest regions, cover approximately 40% of ocean floor)

What are divergent plate boundaries?

two plates moving apart (new crust being created)

Three types of divergent plate boundaries?

1. Ocean ridge and rise system (high heat flow/volcanic activity, shallow earthquakes)

2. Young ocean basins (very young rift/ridge systems)

3. On land rifting (continents spreading apart, high heat flow/volcanic activity)

What are convergent plate boundaries?

two plates moving together, where subduction occurs

Three types of convergent plate boundaries?

1. Ocean-ocean (deep trenches, volcanic island arcs parallel to trench)

2. Ocean-continent (deep ocean trenches near continental volcanic arcs ~ Andes, Cascades)

3. Continent-continent (mountain building ~ Himalayas, Alps)

What are transform boundaries?

two plates sliding past each other (low heat flow, shallow earthquakes ~ San Andreas Fault)

What are two examples of calcareous oozes?

coccolithophores and foraminifera (chalk)

What are two examples of silicious oozes?

diatoms and radiolarians (diatomite)

What is the CCD? carbonate compensation depth

depth where the rate of supply of calcium carbonate from the surface is equal to the rate of dissolution

Where are calcareous oozes found?

warm shallow regions above CCD

Where are siliceous oozes found?

colder regions below CCD

Water has high ____ and ____?

latent heats (phase changes ~ melting and boiling require a lot of energy) and heat capacity

When salinity increases, density of water ________

increases

When salinity increases, boiling point of water ________

increases

When salinity increases, freezing point of water __________

decreases

Sources of salinity?

rivers, volcanic gasses, hydrothermal vents at ocean ridges

Sinks of salinity?

sedimentation, subduction, and circulation of water (through ocean ridge system)

The more H+ in a solution, the more ________ it is

acidic

On the pH scale, each step is

10x

42.5‰ (per mille) in percent would be

4.25%

These ions act as a buffer in the ocean, keeping seawater from becoming too acidic or too basic:

Bicarbonate ions (HCO3-)

When less dense water is on top of more dense water, this is considered _________

stable (inhibited mixing)

When more dense water is on top of less dense water, this is considered ___________

unstable (spontaneous mixing)

When water density is equal on both top and bottom, this is considered __________

neutral (easy mixing)

What is the thermocline?

rapid temperature change, separates top mixed water (turbulent) from bottom deep water

What is the pycnocline?

rapid density change

Net transport of Ekman Transport

90 degrees

Surface layer deflection of Ekman Transport

45 degrees

Direction of subtropical gyres in northern hemisphere

clockwise (vice versa in southern hemisphere)

What drives deep currents?

buoyancy forces (gravity is driving force)

Pelagic Zone

area not near the bottom (of body of water)

Benthic Zone

area at bottom of seafloor

Photic Zone

where light exists (includes euphotic and dysphotic zone)

Euphotic Zone

photosynthesis is larger than respiration

Dysphotic Zone

photosynthesis is smaller than respiration

Aphotic Zone

NO photosynthesis

Three trophic groups

1. Producers (autotrophs ~ phytoplankton)

2. Consumers (heterotrophs ~ zooplankton)

3. Decomposers (bacteria, worms)

Biological Pump

exports photosynthetic products from the euphotic zone to the deep ocean