Oceans Chapter 2 and 3

Magnetic reversal are most likely associated with ____________.

changes in the motion of material in Earth's liquid outer core.

A _______ zone is the area where two continental plates collide after any associated oceanic crust has been subducted or scraped off the subducting slab.

suture.

In which location are most neritic sediments found?

A. continental shelf.

Crust, Mantle, Core

Crust: the thinnest and outermost layer Mantle: the thickest layer and middle layer Core: the inner layer and second in terms of thickness

The _______ core is solid, and the ______ core is partially molten.

Inner; Outer

Abyssal clay is often called red clay because these pelagic sediments are rich in the element ___________.

Iron

When two oceanic plates converge, the plate with a greater density will subduct. This plate will partially melt, causing the formation of a line of volcanoes on the overriding plate. This line of volcanoes is called a(n) _________

Island Arc

Earth's layered structure can be modeled based on different strengths and physical properties or into layers having different ________.

Mineral and chemical compositions.

Select all the statements below that are true regarding continental and oceanic crust.

Oceanic crust is largely composed of basalt Oceanic crust is denser than continental crust.

__________ boundaries in maine settings create new sea floor at the __________ centers

divergent; spreading

The age of the sea floor ________ away from the ocean spreading centers.

increases

let us start with a turbidity current that carries a poorly sorted sediment down the continental slope and into the deep ocean. which sized sediment particles likely will be transported the farthest from their origin?

clay.

Measurements of ocean depth have occurred using various techniques for over 2000 years. These measurements are called_________.

soundings.

The thickest deposits of ocean sediment are generally found near ____________.

the continental margins.

Basalt, the most common rock of the oceanic crust , can record the orientation of the magnetic field at the time of its formation because ____________.

the magnetic mineral magnetite aligns itself with earth's magnetic field before the molten rock full cools.

basaltic magma that is extruded slowly onto the sea floor tends to cool quickly into rounded flows called ______ basalts.

pillow

Each lithospheric _____ consists of the upper 80 to 100 km of rigid mantle rock and is topped by either oceanic or continental crust.

plate

seafloor spreading is _____________________.

the lateral movement of the oceanic lithosphere near spreading centers.

_____________ result in volcanic activity that may operate independently of plate boundaries. these volcanoes can form anywhere on a tectonic plate.

hotspots.

the point within earth where an earthquake occurs is called the _________, and the point on earth's surface directly above this location is called the _________.

hypocenter; epicenter

Match the sea floor terms with the appropriate definitions.

Abyssal plains: the flat, deep portions of the ocean floor. seamounts: steep-sided volcanoes on the ocean floor that may breach the surface. Abyssal hills: very common features, less than 1000 m high Guyots: flat-topped, underwater features found at least 1000 m below the surface.

What physical processes are involved in the process of lithification (i.e. turning sediment into rock)

Cementation, compaction, burial.

Primarily composed of granite _________ crust has a lower density and is thicker than __________ crust, which is primarily composed of basalt.

Continental; Oceanic

Match the plate boundary type to the relative motion at that boundary.

Divergent; Plates are moving apart Convergent: Plates are moving toward one another Transform: Plates are sliding past each other

A sunken rift zone is an example of a ______. a sunken rift zone develops as upwelling magma warms and thins the continental crust.

Graben.

The lower mantle where the high pressure results in Earth materials with greater strength is called the ____________.

Mesosphere

Select all the evidence the Glomar Challenger provided to support the theory of seafloor spreading.

Sediment age and thickness increases outward from the ocean ridge system. No oceanic crust older than 180 million years was found.

Match the paleogeographic feature to its description

Tethys: an ocean occupying an indentation in Pangea. Rodinia: the supercontinent that existed before Pangea. Gondwana: the supercontinent of the southern continents of Pangea.

There are two working models of mantle convection. select them from the list below.

Two regions of mantle convection exist: one for the upper mantle and one for the lower mantle. The entire mantle convects as one unit. This is called whole-mantle convection.

the theory that the continents are slowly moving about the earth surface is called _______ drift.

continental

Select the analogy below that describes how continents move about the surface of Earth.

continents are passengers on the lithosphere much like boxes on a conveyor belt.

Which of the following devices would be best used to obtain a continuous and lengthy, undisturbed sediment sample from the sea floor?

corer.

the vertical, cylindric rock sections that are obtained by drilling into the sea floor are called __________.

cores.

the boundaries of the tectonic plates can be outline by plotting the locations of ________ on a map

earthquakes

seismic waves travel through Earth. The waves form when _____________.

earthquakes occur

we know earth has a layered internal structure ____________.

from models constructed using the difference between P- and S- wave travel times and their shadow zones.

the patter of heat flow near ocean ridges is _________.

greatest near the ridge and generally decreases as you move outward from it.

The thickness, composition, distribution, and source of __________ provide oceanographers with valuable information on how earth functions over long time scales.

ocean sediments

ocean-ocean ocean-continent continent-continent

ocean-ocean: this covergent boundary tends to form island arc volcanism as the subducting slab melts and the molten material rises up through the overriding plate. ocean-continent: the volcanoes formed here have an andesitic composition resulting from the mixing of granite and the basaltic magma from subduction zone melting. continent-continent: this type of boundary forms after the complete closing of an ocean basin during other types of convergence.

The theory of ____________ incorporates the ideas of both seafloor spreading and continental drift into a unified model.

plate tectonics.

A polar ________ occurs when the north magnetic field and the south magnetic field switch orientations.

reversal

select the statement that best describes the distribution of earthquake depths.

shallow earthquakes are common around spreading centers and under continental crust, and deep earthquakes generally occur in subduction zones.

S- waves are also called secondary or ________ waves. P-waves are also called primary waves and travel as _________ waves.

shear; compressional

marine sediments are classified using which of the following three characteristics?

size, geographical location, origin and composition.

Transform boundaries occur where two tectonic plates ________ past each other. This motion does not always occur freely, and thus ___________ faults are formed.

slide; transform

The curie temperature is the temperature below which ________.

the magnetic orientation of a rocks magnetic grains are locked in place.

if a freely suspended magnet is pointing vertically downward with its north-seeking end, the magnet is likely at ___________.

the north magnetic pole.

Select the statement below that describes the average age of the rocks that comprise the oceanic and continental crust.

the oceanic crust is generally younger than the continental crust.

The lithosphere is ____________.

the outer rigid surface layer of earth divided into roughly a dozen large pieces.

The magnetic anomalies that match up on either side of a spreading center indicate that _____.

the sea floor is spreading apart by creating new material on each side of the ridge at the same time.

Ocean-ocean and ocean-continent convergent boundaires form ocean ______, and continent-continent convergent boundaries form __________.

trenches; mountains

Select all the causes below that correctly describe why transform faults may occur.

variations in strength or location of convection cells in earth. collisions between sections of the lithosphere changes in speed and direction for plates as they move on a spherical surface.

Guyots (flat-topped seamounts) are the result of _________.

volcanic islands being eroded after moving off the hotspot that formed them.

The repeated opening and closing of ocean basins and the associated formation and breakup of supercontinents is known as the _________ cycle.

wilson

Which of the following are sources of lithogenous particles in the ocean?

windblown dust, Ash from volcanic islands, rocks transported by icebergs.

the oldest rocks in the ocean ( about 200 million years) are much _______ than the oldest rocks on the continents.

younger

A fracture zone is a continuous linear feature of segments of active transform faults and _____________.

"Fossil" or inactive transform faults

True or false: seabed resources have only recently been exploited (beginning in the mid-1900s) because their mining required modern technological devices.

false.

two major models for a mechanism to drive plate tectonics are the ridge-push, slab-pull and convection models. the convection model relies on ________ between the top of the convecting cell and the base of the lithospheric plate, and the push/pull model relies on the ridge _____ and pushing the plate outward as the ridge falls in elevation.

friction; cooling

The weak, deformable layer of the mantle is called the _____________.

Asthenosphere

Which of the following are ways in which hydrogenous sediments form?

carbonates form by direct precipitation, sulfides form as hot, mineral rich water from vents cools very quickly.

What is a fathom?

A 6 foot standard used to measure ocean depth.

Assuming an isostatic balance beforehand, what adjustment will occur if rock is removed from the continental crust via erosion.

The continental crust will rise.

Put the following sediments in the correct order according to size, with the largest particle type on the top and the smallest on the bottom.

1. boulder 2. pebble 3. sand 4. silt 5. clay

Starting at the bench and moving seaward, put these features in the correct order in which you would encounter them (assuming you could walk on the sea floor)

1. continental shelf 2. continental shelf break 3. continental slope 4. continental rise.

Place the following plate tectonics events in order, with the youngest ( most recent) on top

1. the collision between India and Asia. 2. The separation of Australia from Antarctica 3. The breakup of Pangaea to form Laurasia and Gondwana 4. The formation of the supercontinent Pangaea.

The average seafloor spreading rate is between _______ per year.

2 and 10 cm

Tectonic plates move toward each other at ____________ boundaries

Convergent

Match scientists to their contributions to the understanding of how earth's surface changes.

Edward Suess: proposed that the southern continents has once joined into a single continent now called Gondwanaland. Alfred Wegener: proposed the theory of continental drift and that there was a supercontinent now called Pangaea Francis Bacon, George Buffon, Alexander von Humboldt: Noticed the possible "fit" between the African and South American continents.

Match scientists to their contributions to the understanding of how Earth's surface changes.

F.J. Vine and D.H. Matthews: proposed that the matching magnetic strips on either side of a spreading center represented a recording of polarity reversals. Alfred Wegener: proposed the theory of continental drift. Harry Hess: promoted the concept of large thermal circulation cells within Earth that are heated by radioactivity and heat from the core.

True or False: The position of the north and south magnetic poles is constant over human time scales.

False.

The __________ is the rigid surface layer of earth consisting of the crust and shallow mantle rocks fused together.

Lithosphere

The region of the mantle with slow seismic velocities is called the _______.

Low velocity zone (LVZ)

A convection cell in the mantle is the ___________.

Pattern of movement mantle material takes as it heats and cools.

select all the lines of evidence Wegener used to support his theory of continental drift.

Patterns of glaciation The geographic fit of the continents The fossils of plants and animals.

What are gas hydrates?

Solid, icelike structures composed primarily of methane.

The difference between surface and body waves is surface waves _________.

Travel at the surface of Earth and body waves travel within Earth.

True or False: the lack of a driving mechanism was the main objection to the theory of continental drift when it was first proposed.

True

Earth's magnetic field is similar to what would be expected if a giant bar magnet was located within Earth. it is aligned _________.

about 11.5 degrees off earth's axis of rotation.

Which of these features is not part of the continental margin?

abyssal plain

The existence of small ecosystems that can exist in sunlight-free areas by using microorganisms extracting stored chemcial energy as the base of the food chain was discovered by studying ________.

black smokers at hydrothermal vents

The thickness of pelagic sediments ______________ with increasing distance from mid ocean ridges.

increases.

Select the correct order of layers from the middle of earth outward as modeled by the strengths and physical properties of their materials.

inner core, outer core, mesosphere, asthenosphere, and lithosphere

The principle of _______ describes the balance of forces between internal pressures in the lithosphere and mantle. it allows for the less dense continental material to float on the denser mantle.

isostasy

Lithogenous sediments, those that are derived from preexisting rocks, are often also described as terrigenous, meaning that they derived from ______

land.

The mohorovicic discontinuity (the moho) is the upper surface of the ___________.

mantle

The mesosphere is a region in the _________ where the material is solid and has a greater _________ than the material above it.

mantle; strength

If sedimentary rock is subjected to increased temperature, pressure , and chemistry, ______ rock, such as slate, results.

metamorphic

Which of the following represent the highest valued resources extracted from the sea floor or below?

oil and gas

The difference between the full and half spreading rates is the half spreading rate is the rate at which ____________.

one plate moves away from the ridge, whereas the full spreading rate is the rate at which two plates move away from each other.

Biogenous sediments are derived from ___________

organisms.

The study of ocean basin history through the analysis of sediments is called _________.

paleoceanography.

The lateral movement of the oceanic lithosphere near ocean ridges is called seafloor ____________.

spreading

The areas in which new sea floor and oceanic lithosphere are formed are called ______ centers, and the areas where older oceanic lithosphere is recycled as it descends and melts are called ______________ zones.

spreading; subduction

The S-wave shadow zone (where the waves are not felt at the surface of Earth) occurs at an angular distance greater than about 104 degrees from the location of an earthquake because the waves are _________.

stopped by the liquid outer core.

Plate _______ is the unified model that describes the fragmentation and movement of the lithosphere into seven major plates and a number of small ones.

tectonics

Body waves change direction (refract) within Earth mainly because _________.

their speed changes as they move between materials with different physical properties.

The San Andreas fault in California is an example of a long _________ fault.

transform

The characteristics listed below apply either to active or passive margins. select all the characteristics of active margins.

Represents a plate boundary Ocean trenches possible Modified by tectonic movement and volcanoes.

What features of the ocean floor are over 40,000 miles (65,000 kilometers) long and are found running through ever ocean?

Ridge and rise system.

A continuous series of seamounts very close together formed from a hotspot near a spreading center is called a ________ ridge.

transverse.

true or false: the thickness of the oceanic lithosphere increases with age.

true