OCE 1001 Chpt 4

Why does calcareous material dissolve below the CCD

Below the CCD, weak acid is formed, which dissolves calcareous material.

What do freeze-thaw and salt weathering have in common

Both freeze-thaw and salt weathering require rain and force rocks apart physically

A. siliceous ooze B. quartz sand C. rock fragments D. clay E. volcanic ash

Siliceous ooze

Which of the following statements best describes the topography/appearance of the land surface at the placemarks labeled D?

The topography of the landscape at the placemarks labeled D is similar to the topography of the seafloor at placemarks A and B.

Which of the following contains calcium carbonate (CaCO3)

foraminiferans

Pelagic clays contain lots of material that settles to the seafloor through the water column and are

less than 30% biogenous material.

Sediment that begins as rocks on continents or islands is called:

lithogenous (terrigenous) sediment.

Sediments derived from pre-existing rocks on land are called:

lithogenous.

Calcium carbonate is most likely to dissolve in water with which characteristic

low salinity

Of the following sediments, which one(s) is/are considered hydrogenous

manganese nodules coatings of metal sulfides near black smokers

The most abundant mineral in lithogenous sediments is

quartz

Oozes are uncommon on continental margins because

the biogenous component tends to be overwhelmed by the amount of lithogenous material derived from the nearby continent

In the demonstration, what does the apple represent

the deep sea floor

What is suspended load

the fine-grained particles that travel in the water column above the stream bed

Which is the best definition of glacial snow line

the line dividing zones of accumulation and melting of ice at the surface of a glacier

Which term best describes the seafloor structure around placemarks A and B

wave-cut bench

Sediments with all grains of about the same size are classified as

well sorted

Which of the following are part of the bed load

-gravel -sand

Of the following environments, where would you expect to find large amounts of lithogenous sediment?

-on the continental shelf -in deep trenches not far offshore

Marine sediments provide valuable clues about which of the following Earth history events?

-the climate on Earth millions of years ago -past catastrophes, such as major extinction events -the ancient geographical locations of ocean basins -movement of the ocean floor -previous ocean circulation patterns

What is the elevation of the platform located at placemark B? (Answer to the nearest meter.)

0 meters

What is the approximate depth of the calcite compensation depth (CCD) in the ocean

3 miles (4.5 kilometers)

Calcareous oozes are represented by the number(s)

4

Examine the proportion of sediment types in the Pacific Ocean, Indian Ocean, and the Atlantic Ocean

Abyssal clays are more abundant in the Pacific than the Atlantic because calcareous oozes dissolve before reaching the sea floor in the latter ocean basin.

Which of the following is not an important control on oceanic sediment accumulation

All the above factors are important.

This composite photomicrograph image shows various types of calcareous marine microorganisms that are found in sediment. Match the correct letter to the name and correct description of each organism listed below

B. Foraminifers A. Coccolithophores (multiple) C. cocoliths (individual plates) E. Diatom (siliceous) D. Coccolithophore (single)

This composite photomicrograph image shows various types of siliceous marine microorganisms that are found in sediment. Match the correct letter to the name and correct description of each organism listed below

B. Radiolarian, showing long appendages D. Diatom, top niew C. Radiolarian, spherical shape A. Diatom, showing both halves of its test

This global map shows the distribution of different types of marine sediment (different colors). Match the correct letter to the sediment type listed below.

B. abyssal clay A. siliceous ooze: diatom D. calcareous ooze C. neritic continental lithogenous E. siliceous ooze: radiolarian

Why is this drilling process called rotary drilling

Because the drill bit turns around in a circle

On the world ocean pie diagram below, match the percentage to the correct type of sediment.

C. siliceous ooze B. calcareous ooze A. abyssal clay

What would happen if the depth of the CCD were above the top of the mid-ocean ridge

Calcareous ooze would not be found below the CCD.

The cross-section below shows an area of the sea floor that is accumulating sediments. Match the type of sediment/feature with the correct letter

D. calcite compensation depth C. mid-ocean ridge F. upwelling, cool water B. calcareous ooze E. siliceous ooze A. abysal clay

Which of the following organisms are responsible for the creation of siliceous ooze?

Diatoms Radiolarians

By looking at the degree of erosion of the platforms, arrange the three platforms (B, D, and F) in order from oldest (formed longest ago) to youngest (formed most recently)

F, D, B

Calcareous ooze is found in cooler waters at depth around the world.

False

Radiolarian tests are dissolved beneath the carbonate compensation depth

False

Under what conditions will the front of a glacier remain stationary

Glacial fronts remain stationary when melting and snow accumulation are equal

How does siliceous ooze accumulate on the seafloor if silica-based residues are dissolved slowly at all depths

Silica tests accumulate faster than seawater can dissolve them.

What is salt weathering

The formation of minerals in rock cracks during the evaporation of salty water, forcing rock apart

How would you expect the front of a glacier to move if it undergoes a period of net accumulation, followed by net wastage, and finally a period of net accumulation?

The glacier's front would move forward, backward, and then forward again

What must have happened to produce the three platforms you see here?

The land rose (or sea level dropped) in at least two episodes. First, after the platform (a wave-cut bench) at placemark F was formed, the land rose approximately 130 meters, and the platform at the placemarks labeled D and sea stacks at placemark E were formed. A second uplift of approximately 30 meters left the platform at the placemarks lebeled D 30 meters above sea level. The construction of the platform at placemark B began then and continues today.

Which of the following conditions allows for calcareous ooze to be found beneath the CCD? Select only one answer.

The ooze accumulates above the CCD and then is covered before being transported to deeper depths by sea floor spreading.

Which of the following statements best describes the seafloor surface in this area

The seafloor is relatively smooth, and the water is not deep at all.

How would a snow line on a glacier move as a glacial front is advancing

The snow line would move downslope.

What do manganese nodules, metal sulfides, and evaporites all have in common?

They all precipitate from water oversaturated in their respective minerals.

Which of the following statements best describes the nature of those ridges

They, like the landforms at the placemarks labeled C, are ridges of resistant rock that stand above a broad flat "platform" that surrounds them, though the ridges near placemark E are above sea level and the others are below.

Coastal sand dunes are usually well sorted due to winds

True

Texture refers to the size and shape of sediment particles.

True

The organisms that contribute to biogenous sediment are chiefly algae and protozoans

True

Why does water frozen in the cracks of a rock help to break down the rock

Water expands when frozen and physically forces the rock apart.

What is calcareous ooze

a fine-grained, deep ocean sediment containing the skeletal remains of calcite-secreting microbes

Sediments that are poorly sorted were most likely deposited by:

a glacier.

The most likely place to find abundant manganese nodules is on the

abyssal plain far from a continent.

As a whole, the pH of surface waters of the ocean is slightly

akaline

What common household item is used in this video to demonstrate rotary drilling?

an apple corer

ice rafting

associated with glacial deposits

turbidite

associated with submarine canyons and deep-sea alluvial fans

What are the three types of loads carried by streams?

bed load, suspended load, dissolved load

Sediments derived from the remains of the hard parts of once-living organisms are called __________ sediments

biogenous

coccolithophores

biogenous sediment

siliceous ooze

biogenous sediment

The depth at which calcite dissolves rapidly in the ocean is called the __________.

calcite compensation depth or CCD

Two common types of chemical compounds found in biogenous sediments are __________ and __________.

calcium carbonate; silica

Carbon dioxide (CO2) combines with water (H2O) to form

carbonic acid (H2CO3)

Complete this analogy: Bouncing is to sand as suspension is to

clay

You take a sediment sample from the ocean floor at a depth of 5500 m. The area has low biological productivity and the CCD is at 4500 m depth. Your sample will probably consist of

clay

What have oceanographers determined from analyzing sea floor cores?

climate change and past extinctions

Ocean sediments provide all the following mineral resources excep

coal

Calcite-secreting organisms such as __________ and __________ live in the ocean's sunlit surface waters and form the basis of most marine food webs

coccolithophores; foraminifers

tektites

cosmogenous sediment

Sediments with an extraterrestrial origin are called:

cosmogenous.

What three steps are required for calcareous ooze to exist below the CCD

deposition of calcite shells above the CCD, cover of these shells by a non-calcareous material, and movement of the sea floor over millions of years

The two major types of microscopic, planktonic organisms that produce siliceous oozes are __________ and __________.

diatoms; radiolarians

Forams, which are composed of calcium carbonate, __________ above the CCD and __________ below the CCD.

do not dissolve; dissolve

Diatomaceous earth, which is composed of silica, __________ above the CCD and __________ below the CCD.

does not dissolve; does not dissolve

Which way does ice flow in a glacier retreating uphill

downslope

Siliceous ooze is particularly abundant on the seafloor at __________ and at __________.

high latitudes; equatorial upwelling zones

The pH scale is a measure of the __________ ion concentration of a solution

hydrogen

Match the term or person with the appropriate phrase. metal sulfides

hydrogenous sediment

halite

hydrogenous sediment

Salt beds of the U.S. Gulf Coast are

hydrogenous sediments

Complete this analogy: Sliding is to gravel as dissolution is to

ions

Sediments found on continental margins are called

nertic

A. coccolithophores B. diatoms C. foraminiferans D. oolites E. radiolarians

oolites

A sediment sample dominated by microscopic lithogenous sediment grains would be classified as a

pelagic deposit

How can pieces of rock in contact with a stream bed move

rolling, sliding, bouncing

Which term best describes the landforms at the placemarks labeled C

sea stacks

All the following are examples of hydrogenous sediment except

stromatolites.

The particles found in some sediment that suggests that an extraterrestrial impact event are

tektites.

A. halite and other salts B. manganese nodules C. metal sulfides D. phosphates E. tektites

tektities

What is the calcite compensation depth, or CCD

the ocean depth below which calcite is unstable and will dissolve quickly

All the following are true concerning neritic sediment deposits except :

they are primarily composed of calcareous deposits of biological origin.

Organisms that live on the ocean floor may be responsible for keeping manganese nodules from being buried in the sediment

true

Tektites are glassy rock fragments created during impact events.

true