EMES 103 Test 1 unc

What percentage of Earth's area is covered in water?

71%

What percentage of Earth's water is seawater?

more than 96%

What is the average depth of the oceans?

4km

What is a typical thickness of the atmosphere?

100km

Which two gasses dominate the composition of the present-day atmosphere?

Nitrogen and Oxygen

Composition of atmosphere:

78% nitrogen, 21% oxygen

What percentage of the atmosphere is carbon dioxide?

.037%- .04%

What is the present-day concentration of carbon dioxide in the atmosphere?

425.24 ppm

What was the CO2 concentration before the industrial revolution?

280ppm

Why and how are maps of Earth's surface distorted?

Why: Earth is a 3D, a map is a flat 2D representation. you can't flatten a sphere without stretching, tearing, or compressing it. distortion is unavoidable.

How: Shape distortion - Some projections stretch landmasses, Area distortion - Sizes of continents or oceans may appear larger or smaller than they actually are. Distance distortion - The spacing between points may be stretched or compressed, Direction distortion

How are latitude and longitude defined?

They are an address of a location on earth, Latitude measures how far north or south a place is from the Equator + lines Run east-west. Longitude measures how far east or west a place is from the Prime Meridian. Lines: Run from North Pole to South Pole

How many kilometers in a degree of latitude?

111km

What is vertical exaggeration?

technique used in maps or cross-sectional diagrams (like topographic profiles) where the vertical scale is stretched more than the horizontal scale

Know how to interpret a contour map.

Why is vertical exaggeration so commonly used in oceanography?

By exaggerating the vertical dimension, geographers and geologists can better visualize and study elevation changes.

How long ago was Earth formed?

4.6 billion yrs

How were conditions on early Earth different than today?

Hot: >8000 °F, Molten surface, rich in toxic gases, Abundant radioactive

Elements, Constant bombardment by asteroids and UV radiation

How long ago did life appear on Earth?

3.7 billion years ago

Were the first life forms chemosynthetic or photosynthetic?

Chemosynthetic

How are photosynthetic organisms related to oxygen in Earth's atmosphere?

They split water into hydrogen and oxygen, thus adding oxygen to the atmosphere and thus made oxygen breathing life possible

How long ago was the most recent ice age?

Began 2.6 million years ago, Ended 11,700 years ago

How much cooler is the average temperature on Earth during an ice age?

10 degrees celsius below those of today

What is a typical CO2 concentration during an ice age?

180-200ppm

How do we know what atmospheric conditions were like during the last half million years?

Ice cores - Tiny bubbles trapped in ice contain ancient air, including CO₂, methane, and oxygen levels

Understand what makes studying the ocean difficult.

1. We do not breathe in water

We must either hold our breath or bring air with us

2. The sea surface is dynamic - waves, ice, winds!

Difficult to travel, Difficult to deploy and find equipment, Sea sickness

3. Water absorbs light and electromagnetic radiation

Difficult to navigate and communicate

4. The oceans are deep

Takes a long time to get to location, Fuel + ship operating costs are high

5. High pressure at depth

Change in pressure can cause the gases in our body to react

6. Seawater is corrosive

Any research in salt water that causes any instrument to be in the water will face this problem

How have people overcome not being able to breathe underwater?

variations depending on the depths traveled, including free diving, scuba diving, submersibles, and submarines

What aspects of the ocean surface make it difficult to work on?

Waves, ice and wind -> Difficult to travel, Difficult to deploy and find equipment, Sea

sickness

Why can't we 'see' well in water, even using various forms of electromagnetic radiation?

Water absorbs light and Electromagnetic radiation limiting communication, blocking GPS and allowing Electromagnetic propagation to only be reached up to 200m away

How does pressure vary in the atmosphere and oceans?

Pressure is determined by weight of fluid above you - we experience atmospheric pressure due to the weight of gas above us. Air is most dense near the surface and less dense aloft . Air pressure decreases exponentially with height

10 m depth in ocean = 1 atm of pressure; i.e. the deeper you go, the more pressure you experience in the ocean

What thickness of water is equivalent to pressure at Earth's surface due to the atmosphere?

10m of water is equal to the weight of atmosphere

What does it mean that the ocean is corrosive?

Any research in salt water that causes any instrument to be in the water will face this problem. It has generally damaging properties to what we use to sample/observe in the water

What is 'fouling'?

Accumulation of unwanted material on a surface (marine organisms) like barnacles who adhere to virtually any solid material and some instruments can be rendered inoperable due to this

What are the 4 primary subdisciplines of oceanography?

Geological oceanography: seafloor topography and sediments

Physical oceanography: salt content, temperature, and currents

Chemical oceanography: chemicals in seawater and in seafloor sediment

Biological oceanography: distributions of plant and animal species

What is the most common way at present to measure ocean bathymetry from a vessel?

Multibeam sonar system

What are techniques for collecting ocean sediment samples?

Grab sample, box corer, Piston Coring, IODP Coring

What is a simple method of collecting sediment, and a complex method?

Simple- grab Sampler

Complex- Coring

What is the 'water column'?

the water in a vertical column between the sea surface and the sea floor

What is a CTD (what does it stand for)?

Conductivity Temperature Depth Instrument

Why is a CTD often used before collecting water samples?

Profile data is transmitted in real time through the wire Based on the water column

profile, decide on which depths to sample

What device is typically used to collect water samples?

Niskin Bottle

Sampling the biology of the ocean is especially challenging - what are some specific reasons why this is true?

1) Marine organisms are widely dispersed.

2) There is a huge size range of organisms in the sea (no single method will suffice)

3) Many species will actively swim away from capture devices

4) Many species are delicate and can be destroyed upon capture

5) Deep-sea species often are destroyed when brought to the surface due to pressure changes

Why is it important to know the volume of water filtered during a net tow?

It's important to know the volume of water filtered during a net tow because it allows scientists to quantify plankton abundance accurately

How are a submersible and a remotely operated vehicle (ROV) similar and how are they different?

Differences- Removing all the space, amenities, and life support systems needed for humans, results in a vastly more versatile, agile vehicle that can dive deeper and stay down longer.

• Information and control of the ROV occurs through a cable back to the mother ship.

• Allows many people (almost limitless) to view the seafloor and operations at the same time. Also, multiple people can provide feedback.

Similarity- Has the same sampling capabilities or better than submersibles.

How are ROVs different from autonomous underwater vehicles (AUVs)?

ROV - human controller operating the device
AUV - no controller, completely automated

What is the ARGO program?

global ocean observation system that monitors temperature, salinity, and currents (data below the surface layer that cant be observed by satellite senors) with autonomous robotic measuring devices (argo floats).The combination of the vertical

capabilities of an individual float combined with the large number of floats provides one of our most comprehensive views of the ocean system. Been in place since 2000, first true global monitoring of upper 1-2 km of world's oceans.

What are some techniques to measure ocean currents?

Drifters, moorings, acoustic current meters

What are the principal layers (shells really) that make up Earth?

Crust (made up of continental and oceanic crust) + upper mantle -> make up the lithosphere

Asthenosphere (upper mantle)

Mesosphere (lower mantle)

Outer core

Inner core

Be able to name the layers and their physical state (rigid, liquid, plastic).

Crust -> rigid

Lithosphere -> rigid

Athenosphere -> plastic

Mesosphere -> rigid

Outer core -> liquid

Inner core -> rigid

What is lithosphere?

the name given to the crust and upper mantle, which together make up the rigid surface layer of Earth

What are lithospheric plates?

Aka tectonic plates are the rigid pieces of Earth's outer shell that move around on the planet's surface.

What types of crust are there?

Continental and oceanic crust

What is the approximate thickness and density of the types of crust?

Continental thickness: 35-40 km

Continental density: ~2.8g x cm^-3

Oceanic thickness: 6-7 km

Oceanic density: 2.9g x cm^-3

What is isostacy and how does it explain the variations in elevation of different types of crust?

The principle that Earth's lithosphere "floats" on the denser asthenosphere beneath it, the elevation of the lithosphere depends on its thickness and density. Continental crust

Is Thicker (20-70 km) but less dense (Like a thick, light block of wood, it "sticks up" higher -> why continents rise above sea level) but oceanic crust is Thinner (5-10 km) but denser (Like a thin, heavy block of wood, it doesn't float as high -> That's why ocean basins sit lower, below sea level).

What are the 3 types of relative motion between lithospheric plates?

Convergent, divergent, and transform boundaries

Know the various combinations of crustal interactions at plate boundaries and the typical forms of surface topography of Earth that are associated with them (e.g. coastal mountain ranges, the mid-ocean ridge, volcanic island arcs, trenches, rift valleys, fracture zones, major mountain ranges).

Divergent → Mid-ocean ridges aka seafloor spreading (oceanic plates), rift valleys (continental plates)

Convergent (Ocean-Continent) → At subduction zones creates Coastal mountain ranges, oceanic trenches

Convergent (Ocean-Ocean) → Volcanic island arcs, trenches

Convergent (Continent-Continent) → Major mountain ranges

Transform → Fracture zones on sea floor, fault lines and earthquakes on land

What are spreading cycles as they relate to movement of lithospheric plates?

Spreading cycles refers to the past 225 million years where pieces of continental crust broke apart, spread out, and rejoined -> pangea (and others before). Its the repeated opening and closing of ocean basins, driven by seafloor spreading at ridges and subduction at trenches, which together move lithospheric plates.

What was the name given to the last supercontinent and how long ago did it exist?

Pangea, existed 225 million years ago

What is convection?

Convection is when fluids that are heated from below (earths mantle/ocean water) rise because their density is reduced and continue to rise until they cool sufficiently and are dense enough to sink back down.

What drives the motion of the lithospheric plates?

Mantle convection currents drag and push on the base of the lithosphere which causes:

Divergence → rising convection currents push plates apart (mid-ocean ridges).

Convergence → sinking convection currents pull plates down (subduction zones).

What are hot spots? Know 2 examples of them.

Hot spots are locations where heat from the mantle flows outward through the crust at a much higher rate than in the surrounding crust, and most hot locations occupy only a very limited area at the earths surface -> aka hot spot.

Hawaiian islands -> like Kilauea

Yellowstone

What are active and passive margins?

Active margins = tectonically active, narrow, steep; passive margins = tectonically quiet, wide, gentle slope.

Active Margins: Occur where continental crust meets an oceanic plate boundary

Characterized by: Tectonic activity → earthquakes and volcanoes are common, Narrow continental shelf and steep slope, Often mountainous coastlines.

Passive Margins: Occur where continental crust meets oceanic crust but NOT at a plate boundary.

Characterized by: Little to no tectonic activity → stable coastlines, Wide continental shelf and gentle slope, Sediment from rivers accumulates over time.

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

120 m

What is isostatic sea level change, and how does it differ from eustatic sea level change?

Isostatic Sea-Level Change is when a portion of continent rises or falls due to cooling, heating, erosion or changes in ice mass loading—does not affect sealevel elsewhere in the world and it takes place very slowly (thousands to millions of years).

Eustatic Sea-Level Chang Occurs when ocean water warms and expands Or when polar ice sheets melt and transfer water from land to oceans. Occur rapidly and synchronously worldwide.

What are the two types of bonds that hold atoms together to form molecules?

Covalent and ionic

Which bond is stronger, and what type holds water together?

Covalent bonds are stronger, as electrons are shared and not exchanged like ionic and it holds water together (hydrogen bonds hold water MOLECULES together)

What does it mean that water is a polar molecule?

one side of the molecule has a slight negative charge (oxygen side), and the other side has a slight positive charge (hydrogen side)

What are the two types of intermolecular bonds that were discussed?

Van Der Waals Force and Hydrogen Bonds

What are heat capacity and the latent heats of fusion and vaporization?

Latent heat of fusion: the amount of heat that must be added to convert ice to water at the melting point temperature. 80 cal/g = 334 joules/g

Latent heat of vaporization- the amount of heat that must be added to water to conver water to water vapor at boiling point temperature

Heat capacity- how much heat is required to raise the temperature of one gram of liquid water by one degree celsius

How does water's values of these properties compare with other molecules?

Waters values are significantly higher than other molecules

Why are water's values of these properties important?

Water's thermal properties moderate climate, stabilize ocean temperatures, and enable the global heat and water cycle.

Why is water able to dissolve more substances than any other material?

water ability to be a universal solvent is b/c of its polarity

What are the major ions dissolved in seawater?

Sodium (Na+) & Chloride (Cl-) two most prevalent ions (by concentration)

• Magnesium (Mg2+) & Sulfate(SO42-)

• Potassium (K+) & Calcium (Ca2+)

How is salinity typically measured at present?

The salinity of seawater (SW) is measured by the electrical conductivity

What is the approximate concentration of salts in seawater, in parts per thousand?

35 PSU

How does temperature influence the amount of gases that can be dissolved in seawater?

Colder water can hold more dissolved gas, Warmer water can hold less dissolved gas, At low temperatures, water molecules move less, making it easier for gas molecules to stay trapped and vice versa

How do pressure, salinity and temperature impact the density of seawater.

• Pressure increases with depth, density increases with pressure

• Salinity increase results in density increase

For water > 25 PSU, density increases as temperature decreases

How does increasing salinity change the freezing point of seawater?

Salinity lowers the freezing point of ice

- Most SW has a freezing point of about -2°C

What colors (or wavelengths) of light are most easily transmitted through water?

Green and blue

How does increasing CO2 concentration in seawater change the acidity (pH) of seawater?

Increasing CO₂ makes seawater more acidic (lower pH) by producing carbonic acid and releasing hydrogen ions.

What are the basic classes of grain size?

Boulder, cobbles, gravel, sand, mud (clay/silt)

What is the smallest size of a sediment particle?

Less than .001 mm (clay can fall under this)

What is meant by 'sorting'?

how uniform the grain sizes are in a sediment sample.

Most sediments are well sorted—they consist of grains of only a narrow

range of sizes.

Some sediments are poorly sorted—consist of a wide range of grain sizes.

What are lithogenous sediments derived from?

fragments of rock, produced by physical and chemical weathering

What are different mechanisms for transporting lithogenous sediment to the sea, and how does each relate to the degree of sorting?

- Rivers/freshwater runoff- Many rivers flow across flat coastal plains

and through estuaries. Lots of time to sort and deposit sediment before reaching the ocean.

- glaciers- Glaciers erode and transport large

amounts of rock particles of all sizes (can be poorly sorted)

-Sediments are deposited in streams or carried to sea on ice rafts.

-large sediment inputs from glaciers since the last ice age ended

- waves- waves continuously erode many coastlines and transport

eroded rock particles away from the shore

- winds- - particles are transported very long distances in the atmosphere. Deserts are important sources of material, especially iron

- landslides- Loose soils on a coastline can collapse by mass wasting (landslides). Often result in poorly sorted deposits.

What is the geographic area on Earth where most of the lithogenous sediment is presently derived from?

Asia

What are biogenous sediments?

sediments sourced from the (usually) hard parts of marine organisms

What types of biology dominate the biogenous sediment?

Calcareous and siliceous producers

Diatoms - s

Coccolithosphores - c

Formanifera - c

Pteropods - c

Radiolara - s

What are the two primary types of molecules that make up the hard parts of biogenous sediments?

Silica and calcium carbonate

What is dissolution and how does it vary between the two dominant types of hard parts?

Dissolution: The process of dissolving a solid substance into a solvent to make a Solution.

- Rate of dissolution of silica is highest at surface. It decreases with depth through the upper 2 km.

- Rate of dissolution of calcium carbonate (CaCO3) is slow near the surface but increases rapidly with depth.

What are hydrogenous sediments?

precipitation of dissolved substances, such as evaporites or manganese nodules

What types of sediment are associated with hydrothermal vents?

discharge heated water with no oxygen but high concentrations of metal sulfides (e.g.FeS, Na2S).

What is a manganese nodule, and where might you find one?

dark brown, rounded lumps of rock, many are larger than a potato, litter areas of the deep ocean floor

What are evaporites? How are they produced?

a type of hydrogenous sediment and are minerals that precipitate when seawater evaporates

- when sea water evaporates and dissolved minerals crystalize

How does particle size relate to sinking rate?

particles sink at a rate depending on their density and size. Greater density particles fall faster.

Particle size matters a lot. Very small particles can take YEARS to fall to the seafloor in the open ocean.

What is the range of sediment thickness in the oceans?

0-10 km

Where is sediment the thickest?

around shorelines

Where is sediment the thinnest?

mid-ocean ridges

What is a typical sedimentation rate?

Sediment accumulation rates - largely < 5 cm/1000 years

Where would you expect to find calcareous sediments in the world's oceans?

Oceanic plateaus and seamounts, and on the flanks of oceanic ridges

Where might you find siliceous sediments?

In the deep basins of the North and South Pacific, South Atlantic, and southern Indian Oceans