Oceanography Test 1

What are the uses of the world’s oceans by historical or modern societies?

Transportation, Trade, Food, Resources, Military, Naval power. 

What is the average salinity of ocean water? (% or ppt)

3 ½ % or 35 ppt 

What type of information is shown on bathymetric maps?

Shown by measuring and charting the topography of the sea floor.

Based on mineral and fossil evidence, how long has Earth had oceans, in terms of billions of years ago?

4.4 billion yrs ago 

How much of Earths surface is ocean? How much is land?

71% is Ocean, 29% land

Which Hemisphere has a higher percentage of oceans?

The Southern Hemisphere has more ocean, 80%. 

What is the continental shelf?

Undersea extension of the continent(shore) and nearly flat.

What is the shelf-slope break?

A point of increased slope on the seafloor, usually 150-200 m deep.

What is the continental slope?

The relativley steep part of the seafloor, the part after the continental shelf and break.

what is the continental rise?

Piles of sediments at the base of the conti. slope.

What are the submarine canyons?

Conti. Margins may have seafloor canyons, they look like river systems. 

what is the abyssal plain?

Flat sediment covered parts of deep ocean. After conti. rise.

what are sea mounts?

Isolated seafloor mountians, usually volcanos.

What are guyots?

Flat-topped seamounts that were eroded by waves.

What is a mid ocean ridge?

A long, seafloor mt. chain.

What is a trench?

A narrow trough.

What ocean basin is the largest by volume & deepest?

710 million km³

Continental islands characteristics?

Composed of continental crust.

Volcanic island characteristics?

Tops of large volcanos protruding above sea level. Ex. Hawaii

low-carbonate islands characteristics?

Composed of limestone, small, widley scattered with lagoons.

High-carbonate island characteristics?

Made of reef rocks above sea level, small, limestone.

Example of mid-ocean ridge in pacific.

Pacific Antarctica Ridge

Example of mid-ocean ridge in Atlantic

Mid-Atlantic ridge

Example of mid-ocean Atlantic basin.

Fundy Basin

Do continental shelves form a significant portion of the Artic Basin’s seafloor?

Yes

Example of mid-ocean ridge in the Indian Basin.

Southeast Indian Ridge

What is the lithosphere?

What plates are made of, Crust + Uppermost mantle.

what is the asthenosphere?

Layer in uppermantle, plates float on it, easily maliable.

what is divergence?

2 plates pull apart.

What is convergence?

2 plates move towards each other

What is subduction?

one plate dives below another.

Where do trenches form?

Where convergence and subduction occurs. 

what is collision?

2 plates crash into each other

What is transform movement?

2 plates slide past each other and create lots of earth quakes.

About how quickly do plates move at mid-ocean ridges?

2.5-15 cm a year

What are fracture zones?

A linear feature on the ocean floor from tectonic spreading.

Example of embryonic ocean?

The East African Rift Valley

Example of a youthful ocean?

The Red Sea

Example of a mature ocean?

Atlantic Ocean

Examples of old age Oceans?

Tethy, Panthalassic, and Pacific Ocean.

Examples of extinct basin?

Arctica basin and Greenland-North Atlantic Ridge

What are nertic sediments?

Deposits found in the neritic zone, a shallow marine environment over the continental shelf.

What are pelagic sediments?

Fine-grained sediments deposited in the deep ocean, far from continental landmassies.

What are lithogenous sediments? 

Weathering & erosion of rocls on the land.

What are biogenous sediments?

Particles made from the skeletal or shell remains of once-living organisms, rather than from rock or other non-biological sources.

What are hydrogenous sediments?

They are formed from the chemical precipitation of minerals directly from seawater. 

What are cosmogenous sediments?

Particles from space, such as cosmic dust and meteorite fragments, that land on Earth and settle on its surface, particularly the ocean floor.

What does sorting mean?

Natural process by which sediment particles are separated and arranged by size, shape, and density.

What does “well sorted” mean?

Particles are of a very uniform size, indicating a consistent and often long-distance transportation and deposition process, leading to higher porosity.

What does “poorly sorted” mean?

Sediments or rocks containing a wide range of grain sizes, from large to small, mixed together.

Characteristics of maturity characteristics?

Low clay content, well sorted, quartz-rich, well-rounded grains. 

What does maturity mean?

How long and how much a sediment has been subjected to weathering, transport, and abrasion in the sedimentary cycle.

What are characteristics of immature sediements?

High clay content, poorly sorted, non-quartz material, sub angular shaped grains. 

What are characteristics of glacially-deposited lithogenous sediments on the seafloor? 

A wide range of particle sizes (from boulders to clays) because glaciers transport and deposit all sizes of rock fragments.

Are glacial sediments expected to be poorly sorted or well sorted?

poorly sorted

What are turbidity currents?

Fast-moving underwater flows of dense, sediment-laden water that travel downhill along the ocean floor, eroding and transporting large amounts of sediment from shallow coastal areas and river deltas into the deep sea.

Ferromagnisian minerals- are they dark or light colored?

Dark

Non-ferromagnisian minerals- are they dark or light colored?

Light

Lithogenous sand are mostly composed of what minerals?

Quartz

4 common types of clays in marine fine-grained sediments?

illite, montmorillonite, chlorite, kaolinite.

Where is kaolinite motsly found in oceans?

Tropical areas

Are beach sediments usually quartz-sized?

no

What are turbites and how do they form?

They are underwater sediment slide depostis, they form from natural disasters.

Where are turbidites mostly deposited?

deep-water enviornments

what color do abyssal clays have?

Reddish-brown

Siliceous biogenous sediments are composed of what specific material?

opal

Characteristics of diatoms?

1 celled, planktonic, photosynthetic, 2-part lacy opal skeleton

Characteristics of radiolarians?

1 Celled, planktonic, predators, one part opal skeleton.

Characteristics of silicoflagellates?

one celled, planktonic, photosynthetic, one part opal skeleton.

Characteristics of coccolithophores?

one celled, planktonic, photosynthetic, cells covered in CaCO3. 

Burial & solidification of carbonate ooze results in what type of rock?

chalk

What is CCD?

Depth of a ocean in which solid CaCO3 content of seawater becomes 0%.

What us lysociline?

Level in which a rapid decrease in soild CaCO3 content begins.

Can Calcareous oozes form below the CCD, in the deepest of the deep portion of the oceans? 

Not usually

What 3 factors control ooze formation & deposition?

Productivity, Destruction and dilution.

Basics of manganese nodules?

Rock concretions on the deep seafloor composed of concentric layers of manganese and iron oxides around a central core, like a shell or shark's tooth.

What are black smokers?

Hydrothermal vents on the ocean floor that release extremely hot, mineral-rich water, which mixes with cold seawater and creates dark, billowing plumes that look like smoke.

What specific minerals are black smoker chimneys commonly made of?

Metal sulfide minerals, primarily iron sulfides.

What is glauconite and how does it form?

A dull, greenish iron-potassium mica mineral that forms as pellet-like grains in shallow marine environments, giving rise to the name "green sand". Forms through the chemical alteration of pre-existing porous materials like fecal pellets, sponge spicules, or detrital clays, which are then modified by the uptake of potassium and other elements from seawater.

What are evaporites and how do they form?

Evaporites are sedimentary rocks formed from the crystallization of minerals when water evaporates.

What specific minerals are common in evaporite deposits?

Halite, sylvite (KCl), and fluorite.

What are oolites?

A type of sedimentary rock formed from ooids.

Where do cosmogenous sediments come from?

outer space

Examples of cosmogenous sediments?

Cosmic dust (microscopic, iron-nickel spherules), tektites, and glassy nodules.

In what portion of the seafloor sediment accumulation rates the highest and the lowest? What type of deposits are these?

Highest at continental margins, particularly near river mouths, and lowest in the deep ocean basins. Clastic sediments.

What is a covalent bond?

A type of chemical bond where two atoms share pairs of electrons to achieve a stable electron configuration, typically filling their outermost valence shells.

What is a hydrogen bond?

A type of chemical bond where two atoms share pairs of electrons to achieve a stable electron configuration, typically filling their outermost valence shells.

Does water have a high heat compacity?

Yes.

How much heat does it take to warm up a large body of water?

Lots

How much needs to be taken away to cool down a large body of water?

Lots

How does density of pure water change as it is cooled from 100*C to 4*C?

It becomes heavier.

How does the density of pure water change as it is cooled from 4*C to 0*C?

It becomes lighter weight.

What is considered Hyposaline?

< 30 %

What does hypersaline?

> 38 %

What is Brackish? 

< 10 %

What is Brine?

> 48 %

What are the #1 and #2 most common dissolved inorganic ions in seawater?

chloride (Cl⁻) and sodium (Na⁺)

What does evaporation do to seawater salinity? 

Raises salinity 

What does precipitation do to salinity?

Decreases salinity

What does River runoff do to salinity?

Decreases salinity.