earth 222 from quizlet

What is 'oceanography'?

The scientific study of the oceans, with the goal of understanding the processes and phenomena that take place in the marine realm. Okeanos: "the great outer sea", Graphos: "drawing and describing"

Which are the natural sciences applied to the study of the oceans within oceanography?

Geological Oceanography (marine geology), Physical Oceanography, Chemical Oceanography, Biological Oceanography (marine biology)

What were the contributions of Eratosthenes, Hipparcus, and Ptolemy to oceanography?

~ 220 BC: Eratosthenes of Cyrene first introduced latitude and longitude, systems of imaginary lines dividing the surface of the Earth

~ 150 BC: Hipparchus divided the surface of the Earth into 360 degrees

~ 150 AD: Ptolemy showed the world as a globe, with north at the top and east on the right

What are latitude and longitude?

imaginary lines that can tell you your exact location on the planet. lines of LATITUDE run east to west, BUT they tell you how far NORTH OR SOUTH something is from the equator. lines of LONGITUDE run north and south, but they tell you how far EAST OR WEST something is from the prime meridian.

Why were accurate measurements of longitude difficult to obtain before the middle of the 18th century?

John Harrison produced a much more accurate portable clock (< 3 seconds off), because if clocks were off by just 1 minute, longitude calculations were off by 15 degrees. The longitude problem: The earth rotates from W to E of 360 degrees in 24 hrs, 360 degrees / 24 hours = 15 degrees / hour, you can calculate longitude with time!

What information do you need to determine latitude and longitude? How do you calculate lat and long at sea?

Time (relative to GMT) and angle to the sun at noon (when the sun reaches its highest position above the horizon)

Q. OK, now back to that wild bachelor/bachelorette party. You awaken at night on a ship anchored in a vast sea under a clear, starry sky. Looking up to the sky, you measure the angle between the horizon and the north star, Polaris, at 42°. The next day, at noon, (when the sun reaches its highest position above the horizon, which may not necessarily coincide with noon on a local clock), your watch reads 1520 GMT. Where, at what latitude and longitude are you? A. Latitude: 42°N Longitude: Since GMT is later (3:20 in the afternoon) than local time (~noon), you must be west of London: 3.33 hours ×15∘1ℎ𝑜𝑢𝑟=~50°W So your friends must have left you somewhere in the Northwest Atlantic Ocean.

What were the contributions of the following individuals to our understanding of the oceans? James Cook, Benjamin Franklin, Matthew Maury, Charles Darwin, Charles Thomson & John Murray, Fridtjof Nansen.

1768-1779: Captain James Cook's explorations on H.M.S. Endeavour and H.M.S. Resolution, created charts of the Pacific still used by the Allies in World War II (1770s)

1769-1770: Benjamin Franklin published the first chart of the Gulf Stream

1840's-50's: Matthew Maury created the first reliable wind and current charts

1831-1836: Charles Darwin's voyage on the HMS Beagle. He studies geology and biology of the South American coastline

1872-1876: Charles Wyville Thomson and John Murray directed the first modern, deep-ocean, global sampling expedition on the HMS Challenger. They visited all oceans, covering 127,000 km

1893-1896: Fridtjof Nansen allowed his ship Fram to be trapped in the Arctic ice pack The Fram and its crew drifted with the pack for almost four years and 1,650 km This proved that no arctic continent existed

Which expedition is considered the beginning of modern oceanography?

1872-1876: Wyville Thompson and John Murray directed the first modern, deep-ocean, global sampling expedition on the HMS Challenger. They visited all oceans, covering 127,000 km

Why is the Glomar Challenger important?

The Glomar Challenger was the first research vessel specifically designed in the late 1960s for the purpose of drilling into and taking core samples from the deep ocean floor.

What are ROVs?

Unoccupied, highly maneuverable underwater machines that can be used to explore ocean depths while being operated by someone at the water surface.

What are the contributions of satellites to oceanography?

Satellites can measure various ocean properties like temperature, ice cover, roughness (waves), and water color (indicating plankton abundance)

What is the Big Bang? When did the universe form?

An explanation of how our universe formed

expanded from an initial state of high density and temperature (~14 bya)

What are galaxies, nebulae, stars?

Galaxy: huge rotating aggregation of stars, dust, gas, and other debris held together by gravity

Nebulae: clouds of dust and gas within galaxies, from which stars form

Star: massive sphere of incandescent gases

How did the Earth form and when?

~ 4.6 bya, when gravity pulled together gas and dust that was orbiting the sun

What is the process of density stratification?

~4 bya: Earth's core is very dense (iron, etc.) whereas the outer rocky regions become progressively less dense towards the surface.

How did the ocean form?

Water vapor and other gases separated out from the rocks that make up the bulk of the Earth and were outgassed on the surface, forming the atmosphere and the oceans

What is outgassing and why is it important?

A process, resulting from heating, by which gases and water vapor are released from molten rocks. It is how our oceans and atmosphere were formed

What is the main source of water on the Earth?

The degassing of the mantle

What is the origin and evolution of the atmosphere?

The 'first' atmosphere was stripped away by solar wind

The 'second' atmosphere was outgassed from inside the Earth

Earth's present atmosphere is a 'third generation' atmosphere (oxygen revolution)

Why did the Earth lose its initial atmosphere?

Primary atmospheres are very thick compared to secondary atmospheres like the one found on Earth. The primary atmosphere was lost because it was so hot (and the atoms moved so fast) that it escaped Earth's gravity and drifted off into space

What is the oxygen revolution?

Organisms learned how to do photosynthesis, and oxygen molecules were released into the atmosphere and aquatic environments

What is the importance of photosynthesis for the Earth's evolution?

Converts water and carbon dioxide into sugar and oxygen

water and carbon dioxide were in the atmosphere between ~ 4.5 and 3 bya, and photosynthesis converted them to the oxygen that was necessary for life as we know it

When and where did life begin?

~ 3.5 bya, life started in the oceans

How did the HMS Challenger measure depth?

1872-1876: Challenger Expedition

First systematic bathymetric survey

Lead lines used to measure depth, lowered ropes knot by knot to track depth, but the ocean floor is not flat

What is a lead line?

A rope or line, with graduated depth-markings and a lead weight attached to the end

What is echo sounding and how does it work?

This method is based on the reflection of a sound impulse from the sea floor

Depth (D) is determined from the velocity (v) of sound in seawater (~1,450 m/sec) and the time required (t) for the impulse to make the "round-trip" from the surface to the seafloor and back to the surface: D = v * t * (½)

How do you calculate water depth from sound time travel?

D = v * x (½) t

What are the problems associated with the use of echo sounding (think of wide beam bathymetry)?

Sound beams spread out and exaggerate, meaning the depth you measure might not be the actual depth of directly below you (just the first sound you receive again)

What are the advantages of single focused sound beam bathymetry?

Beam is narrower, less margin for inaccurate measurements (more likely directly below you)

Who was Marie Tharp? What was her major contribution to our understanding of the shape of the bottom of the ocean and plate tectonics?

From Yspilanti, MI, with an MS degree in Geology from UofM

Geologist and oceanographic cartographer

In 1950s she identified the presence of the Mid-Atlantic Ridge and the Rift Valley opening the way to the theory of Plate Tectonics and sea-floor spreading, using soundings from 1946-1952 and 1926

At the time, many scientists including Bruce Heezen (her long-time collaborator) believed that was impossible and he ridiculed her theory as "girl talk"

Tharp and Heezen published their first physiographic map of the North Atlantic in 1957

Tharp's name does not appear on any of the major papers on plate tectonics that he and other published between 1959 and 1963

Tharp later identified that the rift valley extended along with the Mid-Atlantic Ridge into the South Atlantic, and found a similar valley structure in the Indian Ocean, Arabian Sea, Red Sea, and Gulf of Aden, suggesting the presence of a global oceanic rift zone

In collaboration with the Austrian painter Heinrich Berann, Tharp and Heezen realized a map of the entire ocean floor, which was published in 1977 by National Geographic under the title of The World Ocean Floor

Although still recognized and attributed to for her work today on the Mid-Atlantic Ridge, it was Heezen, who at the time in 1956, put out and received credit for the discovery that was made

What is a multibeam echo sounder?

Same as echo sounding, but with multiple sound beams, which allows for more 3D imagery. Example: Sea Beam has 16 beams, Sea Beam 2000 has 121, and can collect much more data

What is a side-scan sonar?

A "towfish" is towed behind a ship and emits rapidly repeating fan-shaped wedges of high intensity, high frequency sound

the sound wedges bounce off the ocean floor and travel back to the towfish, when an instant image is produced (perpendicular to motion of towfish)

multiple parallel passes over an area can result in a mosaic map of the area. Produces photo-like pictures, but not good at measuring depth because you have to account for its distance below the surface

How does satellite bathymetry (altimetry) work?

Works similar to Echo Sounding, but uses electromagnetic waves

measure time from satellite to sea surface and back

Compare the various techniques.

Multibeam echo sounders most accurately measure depth, side-scan sonar captures the most detailed images, and satellite bathymetry is the most efficient/commonly used

Why is it important to map the seafloor?

Seafloor mapping is important for regulating underwater exploration and extraction, and for learning more about Earth's oceans

How is the surface of the Earth distributed over continents and oceans?

71% of the planet surface is covered by liquid water

What is the hypsographic curve and what does it tell you?

Plots the amount of Earth's surface at each elevation or depth

Where is the geological continent/ocean boundary?

Geologic continent-ocean boundary is 2,000 m below sea level (mbsl)

Name the major oceans and their main characteristics.

Pacific Ocean: ~ 50% of ocean surface, Deepest: average 4,200 m, Ringed by geologically active features, Lots of islands and seamounts

Atlantic Ocean: Depth: 3,900 m, Long, narrow, with parallel sides, 68% of world's fresh water runs into it

Indian Ocean: Depth: 3,950, Delivery of lots of sediments to northern part

Arctic Ocean: Shallowest:

• 1,000 m, Very broad continental shelves

What are continental margins and how are they subdivided?

Continental margins are the submerged edges of the continents and consist of massive wedges of sediment eroded from the land and deposited along the continental edge. The continental margin can be divided into three parts: the Continental shelf, the Continental slope, and the Continental rise.

What are the continental shelf, slope, and rise?

Continental Shelf: The shallow, submerged extension of a continent. Its boundary (shelf break, average depth 130-150 m) is determined by an abrupt change in slope. Continental Slope: The transition between the gently descending continental shelf and the deep-ocean floor. Continental Rise: Marks the beginning of the deep ocean basins It is formed by the accumulation of sediments at the base of the continental slope.

Draw a diagram of a typical passive continental margin. EXAM QUESTION!!

How do submarine canyons form?

Submarine canyons cut into the continental shelf and slope, terminating in a fan-shaped wedge of sediment Formed by turbidity currents

What is a turbidity current?

Muddy fluid moves down the slope at speeds up to 27km/hr

What are deep sea trenches?

Narrow steep-sided troughs as deep as 11 km, 50-200 km wide, and thousand of km long. One of the characteristics of deep ocean basins

Draw a diagram of a typical active continental margin. EXAM QUESTION!!

What is the difference between a passive and an active continental margin?

A passive continental margin occurs where the transition from continental crust to oceanic crust is not associated with a plate boundary. In an active continental margin, the boundary between the continent and the ocean is also a tectonic plate boundary, so there is a lot of activity around the margin.

What are the main features of the deep ocean basins?

Abyssal plains, abyssal hills, seamounts, mid-oceanic ridges, and deep sea trenches

What are abyssal plains, abyssal hills, seamounts?

Abyssal Plains: flat portions of the ocean floor covered by sediments

Abyssal Hills: small extinct volcanoes or intrusions of once molten rock covered by sediments

Seamounts: underwater volcanoes that rise abruptly and steeply from the ocean floor

What are the differences between abyssal hills and seamounts?

A seamount is an underwater mountain formed by volcanic activity. Abyssal hills form in the young oceanic lithosphere near mid-ocean ridges, and do not exceed 1,000 meters in height about the seafloor.

How are guyots formed?

Guyots: flat-topped seamounts

Flat-top is significant because it means they used to be islands (only flat if once exposed to air and erosion) Formed: when seamounts are moved off the source of magma, the tops erode over time

What are mid-ocean ridges, rift valleys, and fracture zones?

Oceanic Ridges: The Mid-Ocean Ridge System is a continuous system of mountain chains that runs through every ocean basin. This mountain system is ~2,000 km (1,200 miles) wide and ~2,000 m high (6,600 feet). In the Atlantic and Indian Oceans, there is a valley in the very center of the ridge. Rift Valleys: Low regions that form where Earth's tectonic plates spread apart. Fracture Zones: Long, narrow regions of broken or disturbed seafloor due to a transform fault

What is density?

Density controls whether a substance sinks or floats in a liquid. Density = g/cm^3 = the ratio of mass to unit volume. The density of pure water is 1 g/cm^3.

What is an earthquake?

An earthquake is a phenomenon that results from the sudden release of stored energy in the form of low-frequency waves called seismic waves

How is seismology important for the study of the interior of the Earth?

Seismology: the study of elastic waves that travel through the earth. Tracking the behavior of these waves can teach us about the layers of the Earth

What are the kinds of seismic waves that are used to analyze the Earth's internal structure?

Compressional Waves (p-waves), Transverse Waves (s-waves)

What are P-waves and S-waves?

P-waves: They arrive first at the seismograph. They travel by squeezing and expanding the medium they travel through. They can travel through both solids, liquids, and the air (EX: sound waves). S-waves: They travel by shearing the medium they pass through. S-waves can travel only through solids since particles need to be bonded to each other to propagate these waves (similar to a bull whip)

What are the main differences between the behavior of P-waves and S-waves?

P-waves are faster and can go through liquids

Why do S-waves disappear in the outer core?

They can only travel through solids

How would you expect P-waves and S-waves to behave as they attempt to travel between 1) the mantle and the outer core

and 2) the outer core and the inner core?

1. S-wave disappears and P-wave slows down due to change from solid to liquid

2. S-waves return and both waves speed up

How does density change inside the Earth, from the surface to the core?

Gets denser from surface to core

Describe the classification of the Earth's interior based on chemical composition.

Crust: thin, light outermost layer

Mantle: made of oxygen and silicon with Fe and Mg

Core: consists mainly of Fe and Ni

What are the effects of increasing temperature and pressure on the physical properties of the material inside the Earth?

Increasing pressure raises the melting point of a material. Increasing temperature provides additional energy to the atoms and molecules of matter eventually causing the material to melt. Both pressure and temperature increase toward the center of the Earth, but at variable rates. So, sometimes pressure wins and sometimes temperature wins, which means that materials may behave differently in different spots.

Describe the classification of the Earth's interior based on physical properties of the material inside the Earth.

Lithosphere: rigid outer layer, crust