Chapter 9: Global Ocean
When was the continental shelf last exposed?
Ice age - Pleistocene
What is the second most abundant salt found in seawater?
Magnesium Chloride (mgCL2)
Passive Continental margins
Margin that consists of continental shelf, slope, rise.
Why don't the oceans get saltier over time?
Material is being removed just as rapidly as added
Active continental margin
Narrow and consisting of highly deformed sediments. They occur when oceanic lithosphere is being subducted beneath margin of continent
What is the geologic process of responsible for the presence of water in the oceans?
Outgassing by volcanoes
What is the largest and deepest ocean basin?
Pacific ocean
What are four major ocean basins on Earth?
Pacific, Atlantic, Indian, Arctic
What units are used to describe salinity?
Parts per thousand
Where are high salinities found?
Prcesses that remove freshwater from seawater. Found in high evaperation rate areas and dry subtropic regions
Where aqre low salinities found?
Processes that add large amounts of freshwater to seawater. Near equator
____ are found along the axis of some segments of the mid-ocean ridge system.
Rift valleys
What is the first most abundant salt found in seawater?
Sodium Chloride (NaCL)
What is the third most abundant salt found in seawater?
Sodium Sulfate (Na2SO4)
What are the 3 layers of the ocean?
Surface Zone, Transition Zone, Deep Zone
Definition of continental shelf
The gently sloping submerged portion of the continenetal margin extending from the shoreline to the continental slope
Definition of continental rise
The gently sloping surface at the base of the continental slope
Where trenches do not exist, the steep continental slope merges into a more gradual incline known as the continental ____________.
rise
How wide is the continental shelf of the passive continental margin?
0-900 miles wide. 50 miles average
How wide is the continental rise of passive continental margin?
100s of miles wide
How wide is the continental slope of passice continental margin?
12 miles wide
Seawater consists of __% by weight, dissolved minerals, mainly salts
3.5%
The surface salinity of the open ocean normally ranges from __ % to __% but can exceed __% or be lower than __%
33-38 per thousands, 42 per thousands, 10 per thousands
What is the slope of continental slope of passive continental margin?
5 degrees
The surface of the earth is __% water and __% land
71% and 29%
What is the thermocline?
A layer of water in which there is a rapid change in tempurature in the vertical dimension
What are turbidites and how are they recongnized?
Beds deposited by turbidity currents. Decrease in sediment seize from bottom to top known as graded bedding
What is the fourth most abundant salt found in seawater?
Calcium Chloride (CaCL2)
Variations in salinity of the oceans are primarily a consequence of what?
Changes in water content of the solution
What is the primary source of the salts in ocean water?
Chemical weathering of rocks
What is Oceanography
Composite science that draws on methods and knowledge of biology, chemistry, physics and geology to study the ocean
What is the continental slope
The steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf
What is salinity?
Total amount of solid material dissolved in water
The ____________ are likely the most level places on Earth.
abyssal plains
Features associated with rift valleys include three things:
active volcanoes, recent underwater lava flows, and black smokers.
The ______ varies greatly in width from one continent to another.
continental shelf
The layer of rapid salinity change in the ocean is known as the ____________.
halocline
In the ocean, high salinities are found where evaporation is ____.
high
In the northern hemisphere, there is more ___ so it is refered to __ hemisphere
land, land
The most prominent feature in the oceans, forming an almost continuous mountain range, are the ____________.
mid-ocean ridges
How thick are layers of sediment on the continental shelf of passive continental margin?
miles
What four mineral deposits are found on the continental shelf of passive continental margin?
oil, gas, sand, gravel
Deep, steep-sided valleys that originate on the continental slope and may extend to depths of 3 km are referred to as ____________.
submarine canyons
The layering of the oceans are distinguished by ___ and ___.
tempurature and salinity
The layer of rapid temperature change in the ocean is known as the ____________.
thermocline
The deepest parts of the ocean are long, narrow features known as deep-ocean ____________.
trenches
Downslope movements of dense, sediment-laden water are known as ____________ currents.
turbidity
Deep-ocean trenches in the open ocean are often paralleled by _____.
volcanic island arcs.
The southern hemisphere has more __ so it is called the __ hemisphere
water, water