EMES103 - Exam 1

How much of Earth’s surface is water?

71%

How much of Earth’s water is seawater?

97%

What is the average depth of the ocean?

3,700 m

99% of the atmosphere’s mass sits within ~____ km of the surface

30

What 2 gases dominate the atmosphere, and in what proportions?

Nitrogen (78%) and oxygen (21%)

How much CO2 is in the atmosphere today? and before industrialization?

420-430 ppm (0.04%), 280ppm

latitude

the angle north or south of the equator (0-90)

longitude

the angle east or west of the prime meridian (0-180)

what is vertical exaggeration?

when the vertical scale of a profile or map is stretched relative to the horizontal scale

when did earth form?

4.6 bya

when did life appear on earth? and what was the classification of those organisms?

3.5-3.8 byam chemosynthetic

chemisynthetic

organisms that use energy rather than sunlight, came before photosynthesis

how are photosynthetic organisms related to atmospheric oxygen?

photosynthetic cyanobacteria produced oxygen as a byproduct, gradually building up atmospheric O2 over billions of year (the Great Oxidation Event)- essentially all free oxygen in the atmosphere traces back to photosynthesis

how recent was the last ice age?

Last glacial maximum peaked around 20,000 years ago, ended around 11,700 years ago. Global temp was 5-6C cooler, atmospheric CO2 was around 180-200 ppm.

what sampling technique is used to observe past atmospheric conditions?

ice cores

how far back do ice cores measure?

800,000 years

why is it hard to “see” in water, even with electromagnetic radiation?

water absorbs and scatters most wavelengths of the electromagnetic spectrum very quickly. only a narrow band of visible light penetrates more than a few tens of meters; radio waves are absorbed almost immediately

how does pressure change in the atmosphere vs. the ocean?

atmospheric pressure decreases gradually with altitude. ocean pressure increases with 1 additional atmosphere of pressure every 10m

corrosive

dissolved salts degrade metal and other materials over time

fouling

the growth of organisms (barnacles, algae, biofilm) on submerged equipment

four primary subdisciplines of oceanography

geological, physical, chemical, and biological

how do we measure ocean bathymetry?

multibeam sonar (echo sounding) from a ship

simple vs. complex sediment sampling techniques

simple: a grab sampler that scoops surface sediment

complex: piston or gravity corer, which drives a long tube into the seafloor to pull up an undisturbed vertical sediment record

what is the water column?

the vertical body of seawater at a given location, from the surface down to the seafloor- used as a way to describe depth-dependent properties (temperature, salinity, biology) at one spot.

what does CTD stand for?

Conductivity, Temperature, Depth

Why do we use CTD before collecting water samples?

so we know exactly which depths (e.g., a thermocline or a specific water mass) they want to target when collecting actual water samples

What device is used to collect water samples?

Niskin bottles

What is a Niskin bottle?

hollow tubes mounted on a rosette that can be triggered to seal shut at specific depths, capturing water from exactly that depth

why does the volume of water filtered during a net tow matter?

to convert a raw count of organisms caught into a concentration or density; without knowing the filtered volume, the raw count alone isn’t comparable across tows

what is the difference between submersibles, ROVs, and AUVs?

submersibles are crewed. an ROV (remotely operated vehicle) is uncrewed but tethered and controlled from the surface. An AUV (autonomous underwater vehicle) is uncrewed and untethered, running a pre-programmed mission on its own.

What is the ARGO program?

A global fleet of thousands of autonomous profiling floats that drift with currents, periodically dive and rise while measuring temperature and salinity, and transmit data by satellite; giving continuous, worldwide ocean monitoring.

what techniques measure ocean currents?

drifting buoys/floats, moored current meters, shipboard or moored ADCPs (acoustic Doppler current profilers), and satellite altimetry (measuring sea-surface height differences)

What are Earths layers?

crust, mantle, outer core, inner core

physical state of crust

rigid

physical state of mantle

mostly solid/plastic; the asthenosphere flows slowly like a solid over long timescales

physical state of outer core

liquid

physical state of inner core

solid, due to immense pressure despite the heat

what is the lithosphere?

the rigid outer shell of Earth: the crust plus the uppermost, rigid part of the mantle

What are lithospheric plates?

plates that move independently over the weaker asthenosphere below

What are the 2 types of crust?

Oceanic (thinner, denser) and continental (thicker, less dense)

what is isostasy?

The principle that crust ‘floats” on the denser mantle in gravitational equilibrium, like blocks of wood in water. Thicker, less dense continental crust floats higher, while thinner, denser oceanic crust sits lower (explaining why continents stand above the seafloor)

Divergent

plates move apart

convergent

plates move together

transform

plates slide past eachother

what landforms go with divergent plate boundaries?

mid-ocean ridges, rift valleys

what landforms go with convergent (ocean-continent) boundaries?

deep trench + volcanic arc/coastal mountain range

what landforms go with convergent (ocean-ocean) boundaries?

trench + volcanic island arc

what landforms go with convergent (continent-continent) boundaries?

major mountain ranges (no volcanism, just crumpling)

what landforms go with transform boundaries?

fracture zones

what is convection?

the circulation of material driven by heat

how does convection relate to plate motion?

hot mantle material rises, cools, and sinks in a cycle. This mantle convection is the driving force behind plate movement.

what are hot spots?

fixed plumes of upwelling mantle material that stay in place while plates move over them, creating chains of volcanoes

2 examples of hotspots

hawaii and yellowstone

active margin

sits at a plate boundary and is tectonically active (earthquakes, volcanism)

passive margine

within a plate, tectonically quiet, no boundary nearby

what was the last supercontinents and when did it exist?

Pangea, assembled ~300 mya and began to break apart around 175-200 mya

how much lower was sea level during the last ice age?

120m lower than today

isostatic sea level change

change is local, the land itself rises or sinks

eustatic sea level change

change is global, the actual volume of water in the ocean changes

what bonds hold atoms togehter in molecules? and which is stronger?

covalent and ionic bonds. covalent are stronger and are what hold water’s atoms together

what does it mean that water is a “polar molecule”?

its charge is distributed unevenly, the oxygen end carries a slight negative charge and the hydrogen ends carry a slight positive charge, giving the molecule an electrical “lopsidedness”

what intermolecular bonds hold water molecules to each other, and which is stronger?

hydrogen bonds and van der Waals forces. Hydrogen bonds are stronger and are the main force binding separate water molecules together.

What is heat capacity and latent heats, and why do they matter?

Heat capacity is the energy needed to raise a substance’s temperature; the latent heats of fusion/vaporization are the energy needed to change phase without a temperature change. Water’s values for all three are unusually high compared to most substances- this lets the ocean absorb and store huge amounts of heat, moderating climate.

Why can water dissolve more substances than almost anything else?

Its polarity lets it surround and pull apart charged ions and other polar molecules very effectively

What are the major dissolved ions in seawater?

Chloride, sodium, sulfate, magnesium, calcium, and potassium

What is the typical salinity of seawater?

35 ppt

How do temperature, salinity, and pressure affect seawater density?

Density increases with increasing salinity and increasing pressure, and decreases with increasing temperature (colder, saltier, deeper water is denser)

How does salinity affect freezing point, and temperature affect dissolved gas?

Higher salinity lowers the freezing point of seawater. Warmer water holds less dissolved gas than colder water.

which colors of light travel furthest through water?

blue and green

what are the basic grain-size classes?

gravel, sand, silt, and clay

what does “sorting” mean?

how uniform the grain sizes are within a sediment sample- well-sorted sediment has grains of similar size; poorly sorted sediment has a wide mix of sizes

what are lithogenous sediments, and how are they transported/sorted?

sediments derived from weathering and erosion of rock on land. Transport mechanism affects sorting: rivers- moderately sorter, wind- very well sorted, glaciers/ice- poorly sorted, gravity flows- poorly sorted, deposited quickly

where does most lithogenous sediment come from?

major river systems draining continents

what are biogenous sediments, and what’s their main biological source?

sediments formed from the hard parts of organisms; dominated by plankton (foraminifera, coccolithophores, diatoms, radiolaria) rather than larger animals

what are the two primary hard-part materials, and how does dissolution differ?

Calcareous (calcium carbonate, CaCO3) and siliceous (silica, SiO2) parts. Calcareous material dissolves in cold, high-pressure, deep water (below the “calcite compensation depth”), while siliceous material is less soluble and can persist in deeper water

what are hydrogenous sediments?

sediments that precipitate directly out of seawater through chemical reactions, rather than coming from rock or organisms. Deposits around hydrothermal vents (metal sulfides) are one example.

What are manganese nodules?

a lump of manganese and other metals that slowly precipitates in layers around a small nucleus (like a shell fragment) over millions of years- found scattered across the abyssal plains of the deep seafloor

what are evaporites?

salt deposits left behind when seawater evaporates in restricted, arid basins with limited circulation

how does particle size relate to sinking rate?

larger, denser particles sink faster; smaller/lighter particles sink slowly and can stay suspended or drift long distances before settling

where is ocean sediment thickest and thinnest?

thinnest right at the mid-ocean ridges, thickest near continental margins

where would you expect to calcareous sediments?

warmer, shallower, low-latitude open ocean (above the calcite compensation depth)

where would you expect to find siliceous sediments?

high-productivity zones such as polar regions, the southern ocean, and equatorial upwell zones

where would you expect to find terrigenous (lithogenous) sediments?

close to continental margins, near their land source

what is the earth’s radius?

6,370 km

what % of earth is land?

29%

what % of earth is water?

71%

what % of land is continental ice?

10%

what % of ocean is sea ice?

2%

mercator vs goode’s map projections

mercator: area is badlt distored near the poles, goode’s interrupted: cuts ocean basins to keep land-area proportions accurate

what is vertical exaggeration?

a scale used in maps and cross-sections to make vertical features like hills and mountains taller so they are easier to see. the higher the exaggeration, the steeper slopes looks, even though the real terrain isn’t that deep