Oceanography MT Ch 5
Why is the average sediment thickness in the Pacific Ocean less than that of the Atlantic Ocean?
Ocean trenches trap sediments.
Sediments of the slope, rise, and deep ocean floor that originate in the ocean are called ____.
pelagic sediments
Which oceanographic sampling device played a large role in verifying the plate tectonic theory?
piston corer
Manganese nodules can grow to exceed 1 meter in diameter within about 100 years.
False
The silica from the shells of diatoms dissolves at a faster rate than the calcium carbonate of foraminifera shells.
False
The ____ comprise the highest percent of ocean area, but contain the lowest percent sediment volume.
deep-ocean floor
Which statement is true of sediments in the ocean?
Biogenous sediments comprise a larger area than terrigenous sediments.
Manganese nodules have successfully been commercially mined in the ocean.
False
Neritic sediments are mainly comprised of biogenous sediments due to the proximity to the continental shelf.
False
The mix of rubble at the base of a rapidly eroding shore cliff is an example of a well-sorted sediment.
False
The rate of sediment deposition is fairly consistent throughout the ocean.
False
Calcareous oozes are common at deep-ocean depths below 4,500 m.
False
Biological sediments are the most abundant sediments in the ocean due to the high productivity of organisms along the continental shelf.
False
Clays can remain suspended in the water column for decades before settling due to their small size.
True
Lithification is a pressure-induced process.
True
Neritic sediments are mostly eroded from land.
True
Past sea surface temperatures can be determined from fossils found in deep ocean sediments.
True
Sediment on the continental slopes has an average thickness that is greater than sediment on the continental shelves.
True
Sediments of white or cream color tend to be of biological origin.
True
The compression of small biological particles into fecal pellets increases the rate at which they sink to the bottom of the ocean.
True
The west coast of South America is known for its seasonal upwelling. What kind of sediment is likely to be abundant in this area?
biogenous
An abundance of foraminifera shells would be described as what type of sediment?
calcareous ooze
Which particle size is transported the farthest by waves and currents?
clay
Which particle size has the fastest settling velocity in still water?
coarse sand
A poorly-sorted sediment would most likely be found in a(n) _____.
coastal tidal zone
The White Cliffs of Dover in England were formed as a result of which marine organism?
coccolithophore
What is the primary origin of most neritic sediments?
terrigenous
Which deposits are the result of gravity-propelled currents that produce graded layers of sediment deposits?
turbidites
What occurs below the calcium carbonate compensation depth?
Calcium carbonate begins to dissolve.
Deep-ocean sediments are typically composed of ____.
Fine clays
Which areas of the ocean is most likely to have the least accumulation of sediment?
Oceanic ridge
What is an example of authigenic sediment?
Phosphorite deposits
What is the particle size distribution from largest to smallest?
boulder → granule → coarse sand → coarse silt
Which is an example of an evaporite?
calcium carbonate
What type of deep ocean sediment is most common in the deep-ocean basins surrounding Antarctic?
diatom ooze
Sediments that are gray in color tend to be ____.
high in silica
Which is classified as cosmogenous sediment?
microtektites
Approximately how much of the world's estimated oil and gas reserves are deposited within the sediments of continental margins?
one-third
Deep-sea drilling helped to give rise to the science of _____.
paleoceanography
An area that experiences a high rate of erosion, such as a near shore bay, will have which type of sediments in the surrounding waters?
poorly-sorted sediments
What is the main source of terrigenous sediments to the ocean?
rivers
Most marine sediments are composed of what size of particles?
sand, silt, and clay
Which geological processes explains why the ocean floors are so young?
subduction
What is the most abundant marine sediment?
terrigenous
What type of marine sediment is derived from igneous rock?
terrigenous
