MARS 102 exam 2

what is the principle of Original Horizontality?

Many layers of sediment deposited by water, wind, and ice. Parallel to earth's surface. Law of superposition. When new sedimentary layers bury older ones, a stack of horizontally bedded sediments

what are the 5 main oceans on Earth?

Arctic ocean, Southern Ocean, Indian ocean, Atlantic ocean, pacific ocean

how is bathymetry measured

echo sounders

what was significant about the HMS Challenger expedition and when did it occur?

1872 and 1876, was the first expedition organized specifically to gather data on a wider range of ocean features, including the ocean temperatures, seawater chemistry, currents, marine life, and the geology of the seafloor

what is the physics behind echo soundings?

is sound that is repeated because the sound waves are reflected. Sound waves can bounce off smooth/hard objects in the same way as a rubber ball bounces off the ground. Although the direction of the sound changes, the echo sounds the same as the original sound.

how does echo soundings scale up to map the sub-seafloor with seismic reflection surveys?

measure the time (t) it takes a sound wave with known velocity (m/s) to be transmitted and returned, can then calculate distance (m)

what are the geographic features of passive vs active continental margins

active continental margins tend to have narrow continental shelves. Passive continental margins are not not tectonically active

what are the passive continental margins

Continental Shelf, Continental Slope, Continental Rise, Abyssal Plain

what are the active continental margins

Continental Shelf, Continental Slope, Oceanic Trench

what is the average depth of the shelf break?

Shelf break often occurs ~135 m depth

how does the sea-level change during the quaternary?

Continental shelves were exposed land during glaciations of last 2 million years (The Quaternary) when sea-level would drop >100 m each time

how are continental shelves different on active margins

tectonic activity creates a high degree of relief in the form of islands, shallow banks, and deep basins

what current flows parallel to the continental rise

blank plateau

how do submarine canyons form

by erosion and mass wasting events, particularly on steep continental slops but also on the flanks of volcanic islands

what is the name of the sedimentary deposit at the base of submarine canyons

funnel sediment

how does these sedimentary deposits form in submarine canyons

V-shaped valleys extending across continental shelves and down continental slopes

Describe sedimentation on the abyssal plain.

blanketing of an originally uneven surface of oceanic crust by fine-grained sediments, mainly clay and silt. Much of this sediment is deposited by turbidity currents that have been channeled from the continental margins along submarine canyons into deeper water.

What is the difference between a seamount, abyssal hill, or guyot?

- Mountains >1000 m from seafloor: Seamounts, smaller are called abyssal hills
- Scattered over ocean floors, and dredges bring basalt indicative of volcanic origin (i.e., hot spots)2.
- Table mount (or Guyots)
- Flat-topped seamounts found mostly in the western - --- Pacific
- Hypothesized to be seamounts eroded away, many have corals on top indicating crustal cooling caused subsidence

How do volcanic island arcs form, and in what plate tectonic setting?

From the subduction of an oceanic tectonic plate under another tectonic plate, and often parallel an oceanic trench. This pressure squeezes water out of the plate and introduces it to the mantle. Here the mantle melts and forms magma at depth under the overriding plate.

What is a MOR, and what plate tectonic setting are they found in?

A continuous, fractured-looking mountain range that extends through all ocean basins. Volcanic (basalt), oceanic crust. Center is spreading center and called the rift valley

What are pillow basalts, their texture and chemistry, and where do they form?

Pillow basalts are created when erupting lava at spreading centers is instantly quenched into the solid state by sea water at the sea floor. Pillow basalts can be found in rock outcrops, and provide evidence of ancient seafloor spreading centers

what is chemically and biologically interesting about hydrothermal vents?

Black smokers contain high amounts of dark metal sulfides (Fe, Ni, Cu, Zn) Known for fostering unusual deep-sea ecosystems that survive w/o sunlight and where H2S gas is metabolized by archeons and bacteria.

how do hydrothermal vents form

Created by the return of hot seawater that has circulated through the shallow subsurface, in response to localized geothermal heating. Emerged on the seafloor.

What is the difference between sediment and a sedimentary rock?

Sediment is small rocks that form from all kinds of minerals and rocks while a sedimentary rock is made from all the sediments coming together to form one singular solid object under heat and pressure

What is the difference between a bedding plane and a sedimentary bed?

Bedding planes are sharply defined upper and lower surfaces that make the bed. A sedimentary bed involves many of the bedding planes to form it

What is the field of paleo-oceanography and paleoclimatology?

Paleoceanography- the study of the oceans as they were in the past
Paleoclimatology- the study of previous climates that have existed during Earth’s different geological eras

How does that thickness of sediment vary in the global oceans? What is the major control on sediment thickness?

It varies by the number of sedimentary deposits that are around the world. The amount of sediment thickness that gets buried under itself

When one refers to a depositional environment, what does this mean?

A site where sediments are accumulated, governed by physical, biological, chemical process related to modern and applied to ancient environments.

How is marine sediment collected?

Surface samplers and core devices

What is the difference between lithogenous, hydrogenous, and biogenous sediment?

Lithos- stone; formed from other stones
Hyrdo- water; formed from water movements
Bio- life; formed from life (ex. Shells)

What is the chemistry, primary sources, and delivery mechanisms of lithogenous sediment to the world’s oceans?

SiO2 chemistry, erosion, volcanic eruptions, and windblown dust. Rivers, Ice, and gravity.

What is the chemistry, primary sources, and delivery mechanisms of hydrogenous sediment to the world’s oceans?

Fe-oxide precipitates. Manganese nodules. Water

What is the chemistry, primary sources, and delivery mechanisms of biogenous sediment to the world’s oceans?

Silica (SiO2) and Carbonate (CaCO3). Lithified siliceous ooze and lithified calcareous ooze.

What is the Calcium Compensation Depth?

The point below ocean conditions causes rapid dissolution on CaCO3, mean 4.5 km, range: 3.5 to 6 kms.

how does calcium compensation depth impact marine sedimentation

It impacts it by lowering temps as you go down and creating more sediments at the bottom of the ocean floor.

What is the order of minerals produced when a unit volume (e.g., 1L) of seawater evaporates?

Basalt on the bottom, Carbonate ooze in the middle, and Silica ooze on top

What is the difference between turbidity and contour currents (perpendicular or parallel to bathymetric lines?)

Turbidity current- a rapid, downhill flow of water caused by increased density due to high amounts of sediment.
Contour currents- An undercurrent, typical of the continental rise, which flows along the western boundaries of ocean basins.

what forces drive turbidity and contour currents, and what is the name of their sedimentary deposits

The forces that drive it are the ocean currents, and wind on the surface of the water. The sediment they deposit is called Turbidites.

What is unique about the water molecule in terms of polarity?

partial positive charges on the hydrogens, a partial negative charge on the oxygen, and a bent overall structure.

What is a hydrogen bond and how does that influence the physical properties of water?

A hydrogen bond is a primarily electrostatic force of attraction between a hydrogen atom which is covalently bound to a more electronegative atom or group, and another electronegative atom bearing a lone pair of electrons

What are the definitions of heat, temperature, heat capacity, and specific heat?

Heat- the form of energy that is transferred between objects with different temperatures.

Temperature- the degree or intensity of heat present in a substance or object, especially as expressed according to a comparative scale and shown by a thermometer or perceived by touch.

Heat capacity- the number of heat units needed to raise the temperature of a body by one degree.

Specific heat- the heat required to raise the temperature of the unit mass of a given substance by a given amount.

What are their units (Pro Tip: Accurately known these definitions and units of measure will help you crush your thermo-chemistry chapters in your CHEM courses) - no it wont.

calories or joules per gram per Celsius degree

What is latent heat?

the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.

How does latent heat fuel the intensification of hurricanes?

It was released from condensation

What are the global effects of the heat capacity of the oceans?

It absorbs most of the heat from greenhouse gas emissions.

How does the density of water change as it cools from 16 degrees C to 4 degrees C?

It starts to get less dense as it decreases in temp.

What happens to the density when the temperature of water cools from 4 to 0 degrees C?

It gets less

What happens the volume of water when it freezes, and what causes this at the molecular level?

As water freezes, it expands.

What is the definition of salinity, and what does it exclude?

The quality of water being saline, or the amount of salt in water.

What are the common ways to measure salinity?

An electroconductivity meter

What is the numerical range of salinity in the global surface oceans, and average deep-sea salinity value? (Note: The specific numbers)

33 to 38 ppt

What are the global factors that change salinity: factors of addition and factors of removal?

Evaporation of ocean water and formation of sea ice both increase the salinity of the ocean. However, these "salinity raising" factors are continually counterbalanced by processes that decrease salinity such as the continuous input of fresh water from rivers, precipitation of rain and snow, and melting of ice.

What is the difference between halocline, thermocline, and pycnocline?

Halocline- vertical zone in the oceanic water column in which salinity changes rapidly with depth, located below the well-mixed, uniformly saline surface water layer.

Thermocline- a transition layer between deep and surface water

Pycnocline- a layer in an ocean or other body of water in which water density increases rapidly with depth.

What is the average pH of the surface ocean in the upper ~300 m?

Typically, the surface waters of today's ocean have a pH of around 8.1

What does the average pH of the ocean mean in the deep-sea? (Note: the specific numbers)

Deep ocean is colder and higher pressure, so it can dissolve more gasses like CO2

What is does the problem of ocean acidification refer to?

refers to a reduction in the pH of the ocean over an extended period time, caused primarily by uptake of carbon dioxide? (not completely sure)

What are the three specific, basic relationships for how temperature, salinity, and pressure are related (Slide 20, Seawater).

When temp rises, density decreases, as salinity rises, density increases, and when pressure rises, density also rises.

How does temperature and density vary with latitude, and more specifically, compare temperature and density variability at HIGH latitudes versus LOW latitudes. (Note: Key learning outcome alert!)

The surface water density is highest near the poles and decreases towards the equator. Temperature of surface water increases as you approach the equator.

what are the lower 3 layers of the atmosphere

Troposphere
Stratosphere
Ozone Layer

What layer is the main layer for weather activity?

Troposphere

What boundary defines the top of hurricanes?

mid-latitude frontal boundary

How and When did Earth’s atmosphere and oceans develop?

Liquid water likely beginning filling topographic lows by 4.4 Ga, all oceanic water come from beginning of Earth and was ‘sweated’ out from Earth’s interior to the surface

What are the 3 main atmospheres in Earth’s History (chemistry, timing: what are the 2-3 dominant molecules in each of the 3 main atmospheres)?

Atmosphere 1: Archean air consisted of water vapor, CO2, CH4, and N2 with others. NO Oxygen. Modern volcanic gases.

Atmosphere 2: Carbon dioxide left leaving a dominated nitrogen atmosphere

Atmosphere 3: Modern atmosphere. Rise of O2 at 2.5 Ga. 78% N2 + 21% O2 and others

When did oxygen arrive in the atmosphere, and what is the main sedimentary rock evidence for this event?

Banded Iron Formations (BIFs) evidence the increase of O2, in the atmosphere Some very old BIFs, but most deposited from 2.4 to 1.9 Ga.

How does solar radiation vary by latitude?

Lower latitudes (tropics) receive higher insolation per unit area than higher latitudes (poles). Equal energy, but greater surface area at higher latitudes

What is meant by the concept solar footprint?

Lower latitudes (tropics) receive higher insolation per unit area than higher latitudes (poles). Equal energy, but greater surface area at higher latitudes, referred to as ‘solar footprint’

What drives the changes in the seasons between the northern and southern hemisphere?

Earth’s axis tilt of 23.5 degrees, Vernal Equinox (March 21): Sun overhead at Equator, similar day length globally. Summer Solstice (June 21): sun reaches most northern point in sky, Tropic of Cancer (23.5N). Autumnal Equinox (Sept 23): Sun overhead at Equator, similar day length globally. Winter Solstice (Dec 22): sun reaches most northern point in sky Tropic of Capricorn (23.5N)

What is Albedo?

Albedo is the percentage of incidence radiation this is reflected to space

What is the albedo of snow versus blacktop?

The albedo off the snow would be 80-95% and the albedo of the black top would be 5-10%

What is the Coriolis effect?

Changes in the intended path of movement. Not a true force (no ma). On Earth, causes objects to follow a curved path. Caused by Earth’s rotation.

How does it impact the path of a moving body in the northern versus southern hemisphere?

N. Hemisphere: paths deflect right. S. Hemisphere: paths deflect left. Max effect is at poles, zero effect at equator

Where on Earth is the max vs. min effect?

Max effect: poles
Min effect: Equator

What is the ITCZ? Is it a zone of High or Low pressure?

ITCZ is the Intertropical Convergence Zone, which is a high-pressure zone

Where is ITCZ positioned on Earth on average versus changes seasonally?

Earth elliptical orbit and its 23.5 tilt of earth's axis

Where are the major desert areas on Earth?

They are in the Hadley Cell (0 to 30 degrees)

Why are these major desert areas latitudinally positioned at ~30 degrees?

They are positioned at ~30 degrees because greater than outgoing radiation Equator: incoming radiation greater than outgoing radiation

What is the difference between the trade winds and westerlies?

Trade winds: masses of air that move from subtropical high-pressure belts toward the ITCZ and Westerlies: Some of the air from masses that descend at subtropical highs deflect northward to higher latitude

How and why does land and sea-breezes develop?

Sea Breeze: Rising air during the late afternoon over a heated terrestrial surface pulls air toward the land from the ocean. Land Breeze: At night, land surface cools quicker than ocean, so high-density arid sinks and wind blows from land to ocean.

What is the difference between a tropical depression, tropical storm, and tropical cyclone?

A tropical cyclone with 1-minute average winds at 10m altitude that are >118 km/hr, over the North Atlantic or Eastern North Pacific

Tropical storm: organized system of strong thunderstorms with max. Sustained winds of 62-118 km/hr (cyclonic shape, no ‘eye’)

Tropical depression: organized system of clouds and thunderstorms, max. Sustained winds

What is the difference between a tropical cyclone, typhoon, cyclone, and hurricane?

They’re all the same thing but have different names based on the region they take place in

Tropical cyclones are formed over the South Pacific and Indian Ocean

Typhoons are formed over the Northwest Pacific Ocean

Hurricanes are formed over the North Atlantic and Northeast Pacific Ocean

Where do hurricanes track in the Atlantic most commonly (approximate areas?)

Storms that turn into hurricanes often track on the African coast in the African easterly waves in the Atlantic

What is the Saffir Simpson scale, and what does it refer to?

Measures the intensity of hurricanes. Includes max wind, min surface pressure, and storm surge

What are the meteorological factors that promote hurricane development and intensification?

the release of vast amounts of latent heat of condensation that is carried within the water vapor and released as water condenses to form clouds and rain
Energy released from condensation causes the atmosphere to warm and rise again, releasing more heat

How does ENSO impact hurricane activity?

El Niño years decrease the likelihood hurricane activity because it increases the amount of “wind shear” across the Atlantic basin
La Niña years can contribute to an increase in Atlantic hurricane activity by weakening the wind shear over the Caribbean Sea and tropical Atlantic Basin

What is storm surge?

an abnormal rise of water generated by a storm, over and above the predicted astronomical tide

What part of a hurricane creates the most damaging storm surge in the northern versus southern hemisphere?

Highest surge in right front quadrant of storm, frequently called the ‘dirty side’ in the news

Highest storm surge is dependent upon radius of maximum winds, and direction of winds

Why does storm surge strength differ between hemispheres?

The bottom-left side is considered the weakest section of a hurricane but can still produce dangerous winds. These winds are coming from offshore and wrapping around the backside of the hurricane's eye, so the friction with land has helped them weaken some

What is an over-wash deposit?

Sediment that is specifically mobilized and re-deposited by hurricanes

How can over-wash deposits be leveraged in the sedimentary record to understand long term hurricane activity?

Provide a permanent record of storm passage
Can be used to evaluate storm frequency through time

What are we learning about the Earth’s systems’ potential to generate more intense hurricane activity?

Hurricane wind speed is shown to be increasing, sea surface temperatures are increasing, the rain rate will increase, and regional hurricane frequency will decrease in the future (which will give hurricanes more time to build up and become more intense)

How is hurricane activity likely to change this century from atmospheric CO2 loading from humans (hint: compare intensity vs. frequency)

Regional hurricane frequency will go down overall
The frequency of intense (>cat 3) hurricanes will increase
The rain rate will increase

What is the standard unit of measurement for global transport of ocean currents?

Sverdrup (Sv)

What drives the flow of surface currents vs. deep currents?

Wind-driven currents is what drives surface currents while, density-driven currents drive deep currents

How do we measure ocean currents?

Floating Devices

What are the main components of surface ocean currents?

5 Subtropical Gyres, Equatorial Counter Currents, Subpolar Gyres

What defines the boundary of the subtropical gyres?

Bounded by the Equatorial Currents, Western Boundary Currents, Northern/Southern Boundary Currents, Eastern Boundary Currents

What is the Ekman Spiral vs. Eckman transport?

Ekman Spiral: describes speed and direction of flow of surface water at various depth
Eckman Transport: all layers combine to create an average movement

How and why does Eckman transport vary in the northern vs. southern hemispheres?

Northern: Coriolis Effect causes surface water to move in a direction 45 degrees to the right of the wind direction

Southern: the direction of transport occurs at 90 degrees counterclockwise

What is subtropical convergence and how does it develop?

Subtropical Convergence: deflects surface water to right in northern hemisphere (clockwise rotation)
Develops: in an ocean basin

How does it intensify western boundary currents?

They form closer to western boundary currents. They are faster, deeper, narrower than eastern boundary currents.