oceanography chapter one study guide

what are the 5 subfields of oceanography

geological oceanography

physical oceanography

chemical oceanography

biological oceanography

marine engineering

geological oceanography

studies the earth’s composition, plate tectonics, seafloor sediments and bathymetry, coastlines and beaches, earthquakes, volcanoes and hydrothermal vents

also resources like nodules, oil and gas

physical oceanography

studies waves, tides, currents, and ocean- atmosphere interactions

chemical oceanography

studies the distribution of particles, gases and dissolved chemicals, and the impacts and interactions with geology and biology

biological oceanography

studies marine organisms, micro to macro

ecosystems and the impact of pollutants and disruptions

fisheries

marine engineering

design and construct platforms, vessels and harbors

define science

systematic process of answering questions about the observable world by gathering information (data) and constructing an explanation compatible with all available data

define hypothesis

a tentative explanation for the observations that can be tested and disproven with all available data

define experiment

test that simplifies observations in nature by controlling the conditions under which observation is made

define theory

when a hypothesis is repeatedly supported over a period of time in a variety of contexts and by a variety of studies and researchers, it becomes a theory, which explains that observation

define law

explain patterns in nature that have been observed uniformly, summarizing observations usually in a mathematical or verbal expression

name every ocean

arctic, southern, indian, pacific, atlantic

are there natural divisions between the oceans

nope

average depth of the ocean

about 4000 meters

average temp of the ocean

about 4 degrees celsius

what is the average salinity of the ocean

34 grams per kilogram (about 40)

what is the max depth of the ocean

11,000 meters

is avg elevation of the continents or avg depth of ocean higher?

avg depth of the ocean is greater (4000m vs 840m)

what percentage of water on earth is freshwater

2%

what are the two largest reservoirs of freshwater on earth

glaciers(the biggest reservoir) and groundwater

4 reasons why desalination is bad

expensive

uses a lot of land

taking in water damages the ecosystem

the water it expels also damages the ecosystem

condensation theory

our solar system condensed from a cloud of dust and gas enriched by the remnants of exploded stars

what occurs during accretion

particles stick together and then grow

what occurs during density stratification

the densest materials fall to the center, while the less dense materials take place outward

how did earth form

1- particle accretion

2- meteor and asteroid bombardment heated the surface and added mass

3- gravitational compression

4- high temps turned interior into semisolid volume

equation for calculating volume

density= mass / volume

what are the two original sources of water on ancient earth

comets and asteroids

volcanic outgassing of water vapor

describe the steps that led to the formation of the ocean

1- dense clouds formed from outgassing

2- rain droplets fell, evaporated, and fell again, until the surface was cool enough to hold liquid water

3- puddles with dissolved minerals accumulated into the first salty ocean

how long after earth’s formation were the oceans fully formed

the oceans were fully formed 4 billion years ago

when did the first evidence of life appear in the fossil record

3.5-4 billion years ago

what was the process that transformed the ingredients of life into the first life form

biosynthesis

define biosynthesis

creation of RNA from sugars, amino acids, and nucleotides

what was the first piece of life to evolve (believed)

RNA

LUCA

last universal common ancestor

what modern subsurface system is thought to be similar to the system in which life originated

hydrothermal vents

why were hydrothermal vents the cradle of life

energy rich chemicals are abundant here, and temperature is high

how was oxygen introduced to earth’s atmosphere, and what were the effects of this oxygenation

cyanobacteria evolved, and this was the first organism to carry out photosynthesis, and this created an oxygenated atmosphere, everything that couldn’t consume oxygen died from this

list all 4 pieces of evidence that the continents used to be together in a super continent and have since moved across earth’s surface

1- the continental shelf pieces fit together like a puzzle

2- fossils match across modern oceans

3- geological features connect across modern oceans

4- magnetic signature stored in continental rocks suggests that the continents move relative to eachother

which crust is denser, oceanic or continental

oceanic crust is denser

what material makes up oceanic crust

basalt

what kind of rock makes up continental crust

granite

where is the lithosphere

cool, rigid, outer layer, makes up the continental and oceanic crust, and some of the upper mantle

where is the asthenosphere

hot, partially melted layer, that makes up the mantle

have we ever collected samples of the earth’s mantle?

yes, we dug into the mid-atlantic ridge

isostacy

holds up continents like the way buoyancy hold up boats

isostatic adjustment

when mass if added or removed causing plates to move up or down

examples of isostatic readjustment

melting of ice sheets makes crustal rock go up

what three forces cause tectonic plates to move laterally

mantle convection

ridge push

slab pull

what 3 pieces of evidence support seafloor spreading

1- sonar bathymetry of the seafloor reveals ridges

2- radiometric dating using isotopes to reveal ocean crust is much younger than earth

3- paleomagnetism studies in rocks reflecting earth’s magnetic field at the time of the rock’s formation

what is the half- life of a radioisotope, and how it can be used for radiometric dating

it is the amount of time it takes for ½ of that substances to decay, and it can be used for dating by counting the ratio of daughter to parent molecules

is oceanic crust created or destroyed at mid-ocean ridges

new seafloor is created at mid-ocean ridges

is the youngest oceanic crust close to or far from the continents

the youngest would be far from the continents, because the old rock is constantly being pushed away from its source of creation

why is there no oceanic crust older than 200 million years old, even though earth is much older

because it subducts beneath the lighter continental crust

name the three types of plate boundaries

divergent, convergent, transform

what are the 4 characteristic features of divergent plate boundaries

1- mid ocean ridge

2- volcanos

3- rift valley

4- shallow earthquakes

where does the fluid in hydrothermal vents originate, and how are the chimney structures build

1. they are formed when seawater percolated through porous exposed basalt, gains heat and chemicals from the surrounding rock deep in the crust, and is injected back into the ocean

2. the chemicals dissolved in the hot water react immediately with the seawater, precipitating mineral chimneys

3. the hot water does not boil because of the great pressure at depth

what are the five characteristics of convergent plate boundaries

mountains, volcanos, subduction zone, trench, deep earthquakes

what type of convergence created the deepest point in the ocean, and the mariana trench

ocean- ocean convergence created the mariana trench

how were the hawaiian islands created

a mantle plume or hotspot, as the plate moved away from the plume , it left the islands formed and created the chain of islands

 

how does multibean swath bathymetry work, and what kind of data does it produce

with an array of acoustic beams, a ship can create a full picture of the seafloor

how does chirp sonar work and what kind of data does it produce

a sound beam that modulates the frequency creates a range of sound waves that will bounce off layers of different density, or discontinuities

this allows us to see “through” the seafloor

why is important to know about the presence of methane in sediment

safety while coring or drilling

extraction of natural gas

research in biology or chemistry

how to we detect methane in the sediment

deeper, lower wavelength sounds penetrate deeper but in less detail

chirp shows you shallower layers

pingers reflect just the seafloor

how can satellites detect undersea features like ridges and seamounts

they can detect small changes in sea surface height

the area of the ocean is dominated by which two oceanic provinces

ridges and basin floors

describe active margin and what plate boundary it is found at

active margin is moving plates, and at a convergent boundary

describe a passive margin and what plate it is found at

no plate activity, not divergent or convergent, just a transition from continental to oceanic crust

know where the continental shelf, shelf break, continental slope, continental rise, and abyssal plain is located

where are submarine canyons observed and what are they caused by

they are found on continental slopes

they are started by ancient rivers, when the sea level was lower, and they are carved deeper by turbidity currents and gravity flows

what is a turbidity current

underwater avalanches

abyssal plain, and why is it so flat?

abyssal plane extends from the base of continental rise, and it is flat because the large amount of sediment filled in any crevices or hills

where would sediment cover be the thickest

furthest away from the mid- ocean ridge

how does fast spreading affect the topography

features are spread over a larger area

how does slow spreading effect the topography

more vertical topography and more pronounced central rift

where is the pacific ring of fire and what type of boundary does it represent

it represents active margins, it is marked by convergent boundaries, it is where the worlds most active volcanoes, and deepest earthquakes occur

what are the four benthic zones in order from most shallow to most deep

continental shelf

bathyal zone

abyssal zone

hadal zone

what are the two pelagic zones of the ocean and where are they located

neritic= over continental shelf

oceanic= beyond continental shelf

what defines the vertical zones of the ocean and why

light, because photosynthesis

what are the four vertical oceanic pelagic zones from closest to the surface to furthest from the surface

epipelagic

mesopelagic

bathypelagic

abyssopelagic

how does proximity to continents affect the accumulation rate of sediments

closer to continents= high accumulation rate

what count create a white colored sediment and where would it most likely be found

a white colored sediment is formed from biogenous calcareous ooze

these are found in warm shallow tropical water (high productivity) or below the calcium comphensation depth

how could boulders, pebbles, and cobbles end up in ocean sediment

through high energy transport mechanisms, like melting ice, coastal erosion, landslides, or turbidity currents

what determines the sediment grain size in a region

the energy in the environment

where would you find large grain size

high energy environment

where would you find small grain size

low energy environment

how do well sorted sediments differ from poorly sorted sediments

well sorted= mostly the same size

poorly sorted= varying particle size

what can grain shape tell you

indicated the distance from the source

where would a very large sediment be found

very close to the source

where do terrigenous sediments come from and how are they transported to the ocean

originate at continents, and they are transported by the blowing of dust, erosion of land, volcanic eruptions

describe the sedimentary rock cycle

how did shallow water limestone rock make it onto the peak of mount everest

uplift occured when the indian plate collided with the eurasion plate which then formed the mountain

why do we find fish fossils in the middle of the continental US

due to the colorado plateau, which was once a massive seaway

define ooze

deep sea sediments containing at least 30 % biogenic sediments

describe the main minerals that make up calcareous ooze

carbonate skeletons precipitated by various creatures

what organisms produce carbonate skeletons

foraminifera, pteropods, coccolithophores

what makes up a siliceous ooze

living things that precipitate silica

what organisms produce silica

diatoms and radiolarians

why dont we find carbonate below 5000m in the modern ocean

because it begins to dissolve at cold depths, and it is no longer in its solid form

this is the standard depth of the CCD

define lysocline

depth at which a significant amount of CaCO3 begins to dissolve rapidly

what are two reasons why you might find calcite deeper than 5000 m

because it got burried and wasnt exposed to the water

because the rate of addition is very high and steady