EUSTATIC SEA LEVEL CHANGE

Eustatic- any uniformly global change in sea level

*This may reflect a change in the quantity of

water in the ocean or a change in the

shape/capacity of ocean basins

CONTROLS sea level change exerts an important control on the deposition of

sedimentary strata. In addition, the major discontinuities used to define

allostratigraphic units are caused by sea level changes:

* Regressivie surfaces of erosion - unconformities

* Transgressive surfaces of erosion - ravinement surface

* Maximum flooding surfaces - condensed intervals

* Changes in sea level depend on both local and global controls. Global

controls are particularly important because they may create

allostratigraphic boundaries that are globally correlatable - providing an

important chronostratigraphic tool.

* Global or eustatic sea level changes controlled by two factors:

CONTROLS CONTINUED* Volume of water in the ocean basins

* Ocean volume changes

* Glacial accretion and wastage (glacio-eustatic)

* Liquid water on land surface and in aquifers

* Volume of the ocean basins

* Rate of seafloor spreading = volume of midocean ridges (tectono-eustatic)

* Each of these mechanisms operates within a characteristic time scale and

produces a characteristic range of sea level change. Operating in concert, the

effect is to produce a wide range of overlapping cycles of sea level change, each

with a characteristic time scale also called an order and magnitude (depth).

EL NIÑO AND WORD CLEARANCES

* El Niño occurs every 4 to 12 years

* A warning of the oceans surface off the western

coast of south America when upwelling of cold,

nutrient-rich water does not occur

* Transgressive- to pass over or go beyond

* Regressive- decreasing proportionately with an

increase in the tax base

Sediments:* The ocean floor is mantled with sediment.

* Part of this material has been deposited by turbidity currents and the rest has slowly settled

to the bottom, the thickness of it varies.

* Sea floor sediments can be classified according to their origin into there broad categories.

Terrigenous sediment, biogenous sediments, and hydrogenous sediments.

consist primary of mineral grains that were weathered from continental rocks and transported to the ocean. The very

small particles take years to settle on the ocean floor.

Terrigenous sediments (derived from land)

consist of shells and skeletons of marine animals and plants. The

most common biogeneous sediments are known as calcareous

oozes. These sediments are produced by organism that when its here parts slowly sink through cool

waters they begin to dissolve before getting to the bottom.

Biogeneous sediment (derived from organisms)

*consists of mineral that crystallize directly from sea water though various

chemical reactions one type of hydrogenous sediment are manganese nodules, they are a complex mixture that forms very slowly on the floor of

the ocean basins.

Hydrogenous sediment (derived from water)

Interactions between climate and ocean:

* Oceans and atmosphere store and exchange in forms of heat, moisture, and

momentum.

* The oceans are the earth’s largest reservoir of moisture.

They also absorb and store heat more effectively than land and ice surfaces

* Oceanic heat is released more slowly than on land, keeping coastal areas more

temperate.

* Changes in the energy balance between the oceans and atmosphere play an important role in the planets

climates change.

* Ocean circulation is effected by variations in atmospheric circulation.

* Surface currents are driven by the force of the wind pushing on the ocean

surface.

Interactions Continued

* Do the oceans affect the weather?

* Yes because of their ability to store huge quantities of heat and moisture, the oceans after atmospheric conditions and

the weather.

* For example, tropical storms from over warm hurricanes and typhoons grow and

move, often over land.

Q & A one

* How do the oceans affect global climate?

* Just like the ocean affect weather patterns, they play a major role in the

earth’s climate system.

* Ocean currents mixing with winds and waves can transport heat to a deeper

ocean layer.

Q & A two:

* Why are oceans currents important to climate?

* Ocean currents transport heat and salt

* Sudden shifts in these currents are thought to have initiated past ice

ages.

Q&A three:

* What is upwelling?

* To understand upwelling, you must know that the rotations of the earth causing moving objects to deflect

along their paths- to the right in the northern hemisphere, and to the left in the southern hemisphere.

* The upwelling process moves cooler nutrient- rich water up toward the surface to replace the original surface water.

* Upwelling also occurs along the equator and in the open ocean away from the eastern boundaries but coastal upwelling is the most familiar and most ecologically

important form of this process.

Q & A four:

Ocean Circulation is water current flow in a closed circular pattern within an ocean. Large scale horizontal water motion within an ocean. That transports surface seawater to the polar region where it cools. This cooling releases heat which warms the air and makes the water cold and, therefore, dense enough to sink to the bottom of the ocean. This results in the formation of new deep water which displaces existing deep water pushing it towards the equator. The Deep Water then flows south along the ocean floor allowing more warm surface water to flow into the region to replace it. Ocean basin are the great depression occupied by the ocean on the surface on the lithosphere.

Ocean circulation

Energy from the Sun doesn't fall equally all over the Earth. Most of the Sun's energy enters the Earth at the equator. This leads to large temperature differences between the equator and the Poles. Movement of both the air and the oceans is controlled by these temperature differences and the result is a transfer of heat from the equator to the poles. About half the heat transport around the planet is by the oceans so the oceans are an extremely important part of the Earth's climate control system. If ocean circulation is changed by global warming, major changes in climate are therefore likely. Ocean circulation also transports oxygen from the air into the ocean making marine life possible.

Energy Transfer

*Seawater continuously moves around the globe as if it is on a huge conveyor belt, moving from the surface to the deep waters and back. Because the distance the water has to travel is so large, it takes about 1000 years for seawater to go all the way around the Earth. *The movement of water around the oceans has two parts which are strongly linked:1.a density driven circulation which is driven by the differences in the density of seawater at different locations. The density of seawater depends on its temperature and how salty it is. As a result, this movement is known as the thermohaline circulation.2.a wind driven circulation which results in huge surface currents like the Gulf Stream.

A little more about Circulation

*The Gulf Stream is one of the most important wind driven currents. It transports very warm tropical water from the Caribbean Sea and the Gulf of Mexico across the North Atlantic to northern Europe. The warmth of the water heats the air above and the movement of this warm air is a very important way by which heat is transported northwards. As a result of this heat transport, northern Europe is very much warmer than corresponding latitudes in North America and countries around the Pacific Ocean.

*Tides are the periodic variation in the surface level of the bays, gulfs, inlets and estuaries, caused by gravitational attraction of the moon and sun. Tides affect the entire ocean, they alter current speeds and change the height of the water.

The Gulf & tides

is the misperception or body orientation and induced nausea do to the coriolis force. Some of the most important impacts are the deflection of winds and currents in the ocean. In terms of affecting the wind, as air rises off of the earth's surface, its speed over the surface increases because there’s less drag as the air no longer has to move across the earth's many types of landforms. Because the Coriolis effect increases with an item’s increasing speed, it significantly deflects air flows and as a result the wind. *In the Northern Hemisphere these winds spiral to the right and in the Southern Hemisphere they spiral to the left. Though the circulation is not as significant as that in the air, the deflection caused by the Coriolis effect is what creates the spiraling pattern in these gyres

Coriolis effect

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