The Origin of the OceanThe Origin of the Ocean

The Water PlanetThe Water Planet

AN OCEAN WORLD

• The ocean covers 71% of Earth’s surface • The ocean contains 97% of the water on Earth• The ocean is Earth’s most important feature• The named oceans and seas (Pacific and

Atlantic, Mediterranean and Baltic) are named for our convenience

• They are only temporary features of a single world ocean

• Average ocean depth is about 4½ times greater than the average height of the continents above sea level

Earth is a Water Planet Earth is a Water Planet • oceans occupy 71% of the earth's surface oceans occupy 71% of the earth's surface • not distributed equally with respect to the not distributed equally with respect to the

equatorequator• ocean covers 61% of the northern ocean covers 61% of the northern

hemisphere and 80% of the southern hemisphere and 80% of the southern hemisphere hemisphere

• presence of oceans is function of geological presence of oceans is function of geological activity and planet's location in relation to sun activity and planet's location in relation to sun – too far away -- water will be in a frozen state too far away -- water will be in a frozen state – too close -- water will evaporate too close -- water will evaporate

• Earth is in a perfect location to allow water to Earth is in a perfect location to allow water to be in liquid state be in liquid state

OceansOceans• Today's oceans are traditionally divided into 4 large Today's oceans are traditionally divided into 4 large

basinsbasins – North and South PacificNorth and South Pacific– North and South AtlanticNorth and South Atlantic– IndianIndian– ArcticArctic

• Oceans are really interconnected Oceans are really interconnected • Connected to these 4 large basins are smaller, Connected to these 4 large basins are smaller, marginal marginal

seasseas, such as the Mediterranean, Gulf of Mexico, South , such as the Mediterranean, Gulf of Mexico, South China Sea, Red Sea, Caribbean, Baltic Sea, Bering Sea, China Sea, Red Sea, Caribbean, Baltic Sea, Bering Sea, etc. etc.

• Each basin or marginal sea varies in its ability to Each basin or marginal sea varies in its ability to support life due to both climatic differences and support life due to both climatic differences and shapes and positions of present-day continents shapes and positions of present-day continents

• Ocean basins consist of the deep seafloor (13,000-Ocean basins consist of the deep seafloor (13,000-20,000 ft; 4-6 km) and cover most of the earth's surface 20,000 ft; 4-6 km) and cover most of the earth's surface (30%); continents only cover 29% (30%); continents only cover 29%

Distribution of land and sea by latitude

Hypsographic CurveElevation areas aboveAnd below sea-level

Bathymetric Chart of the Sea Floor

Physiographic Map of the Sea Floor

3-D Computer Generated Image of the East Pacific Rise

The Big BangThe Big Bang

• Event that occurred approximately Event that occurred approximately 13.7 BILLION years ago13.7 BILLION years ago

• All the mass and energy All the mass and energy concentrated at a pointconcentrated at a point

• The universe began expanding and The universe began expanding and continues to expandcontinues to expand

• After 1 million years matter began to After 1 million years matter began to cool enough to form atoms- cool enough to form atoms- Hydrogen- the building block of starsHydrogen- the building block of stars

Galaxies and StarsGalaxies and Stars

• Galaxy- huge rotating aggregation of Galaxy- huge rotating aggregation of stars, dust, gas held together by stars, dust, gas held together by gravitygravity

• Earth, the sun and our solar system Earth, the sun and our solar system is part of the Milky Wayis part of the Milky Way

• Stars are massive spheres of Stars are massive spheres of incandescent gases (hydrogen and incandescent gases (hydrogen and helium)helium)

The Solar SystemThe Solar System

• Our solar system is located away from Our solar system is located away from the galaxy’s centerthe galaxy’s center

• Our sun and the planets originated Our sun and the planets originated from a solar nebula that had been from a solar nebula that had been enriched with heavy elements from enriched with heavy elements from nearby super novaenearby super novae

• Solar system is approximately 5 Billion Solar system is approximately 5 Billion years oldyears old

• Composition is 75% hydrogen, 23% Composition is 75% hydrogen, 23% helium and 2% other materialshelium and 2% other materials

Formation of aProtostar

Center contracts

Center continues to heat up

Protostar radiates more heat

Fusion begins in the stars core

Shockwaves radiate outward releasing material

Material coalesces into planets, moons or comets

Other material is ejected to the periphery

Our Solar System

4 inner planets (terrestrial)

4 outer planets (gaseous)

Solar nebula photographed by Hubble

The EarthThe Earth• CoreCore is composed of mixtures or alloys of is composed of mixtures or alloys of

iron (pressure is more than a million times iron (pressure is more than a million times that at the surface and temperature is that at the surface and temperature is estimated to be at 4000°C); has a solid estimated to be at 4000°C); has a solid inner core and a liquid outer core (earth's inner core and a liquid outer core (earth's magnetic field may be produced by the magnetic field may be produced by the motion of the liquid material in the iron-rich motion of the liquid material in the iron-rich outer core) outer core)

• Layer outside the earth's core is the Layer outside the earth's core is the mantlemantle; it is solid but very hot, near the ; it is solid but very hot, near the melting point of rocks, so it flows almost melting point of rocks, so it flows almost like a liquid, though much slower; it is 70% like a liquid, though much slower; it is 70% of the earth's volume of the earth's volume

The EarthThe Earth

• Outermost layer is the Outermost layer is the crustcrust; it is ; it is extremely thin (is thinner under the extremely thin (is thinner under the oceans than under the continents) oceans than under the continents) – Oceanic crustOceanic crust is made of is made of basaltbasalt (low in silica (low in silica

and high in iron and magnesium) and has a and high in iron and magnesium) and has a higher density compared to higher density compared to continental continental crustcrust, which is made of , which is made of granitegranite (high content (high content of aluminum and magnesium silicate with of aluminum and magnesium silicate with quartz and feldspar) and has a lower density quartz and feldspar) and has a lower density

– Thus, continents lie above sea level and Thus, continents lie above sea level and oceanic crust lies below sea level because of oceanic crust lies below sea level because of density differences density differences

Formation of the Oceans:Formation of the Oceans:Prevailing TheoryPrevailing Theory

• The major trapped volatile was The major trapped volatile was waterwater (H2O). Others included (H2O). Others included nitrogennitrogen (N2), the most abundant gas in the atmosphere, (N2), the most abundant gas in the atmosphere, carbon dioxidecarbon dioxide (CO2), and hydrochloric acid (HCl), which (CO2), and hydrochloric acid (HCl), which was the source of the was the source of the chloridechloride in sea salt (mostly NaCl). in sea salt (mostly NaCl).

• The volatiles were probably released early in the Earth's The volatiles were probably released early in the Earth's history, when it melted and segregated into the history, when it melted and segregated into the corecore, , mantlemantle, and , and crustcrust. This segregation occurred because of . This segregation occurred because of differences in density, the crust being the "lightest" material.differences in density, the crust being the "lightest" material.

• VolcanoesVolcanoes have released additional volatiles throughout the have released additional volatiles throughout the Earth's history, but probably more during the early years Earth's history, but probably more during the early years when the Earth was hotter.when the Earth was hotter.

• Probably, the Probably, the oceansoceans formed as soon as the Earth cooled formed as soon as the Earth cooled enough for water to become liquid, about 4 billion years ago. enough for water to become liquid, about 4 billion years ago. The oldest rocks on the earth's surface today are 3.8 billion The oldest rocks on the earth's surface today are 3.8 billion years old.years old.

Outgassing

Oceans are byproducts of heating and differentiation: as earth warmed and partially melted, water locked in the minerals as hydrogen and oxygen was released and carried to the surface by volcanic venting activity

Origin of AtmosphereOrigin of Atmosphere• Atmosphere evolved in 4 steps: Atmosphere evolved in 4 steps:

– primordial gases, later lost from sun's primordial gases, later lost from sun's radiation radiation

– exhalations from the molten surface exhalations from the molten surface (volcanic venting); bombardment from (volcanic venting); bombardment from icy comets icy comets

– steady additions of carbon dioxide, steady additions of carbon dioxide, water vapor, carbon monoxide, nitrogen, water vapor, carbon monoxide, nitrogen, hydrogen, hydrogen chloride, ammonia, hydrogen, hydrogen chloride, ammonia, and methane from volcanic activity and methane from volcanic activity

– addition of oxygen by plant/bacterial life addition of oxygen by plant/bacterial life

The Hydrologic CycleThe Hydrologic Cycle

• Water occurs as a solid, liquid and Water occurs as a solid, liquid and gasgas

• Amount of water is fixedAmount of water is fixed

• The places where water resides are The places where water resides are called called ReservoirsReservoirs

• Water constantly moves from one Water constantly moves from one reservoir to anotherreservoir to another

Comparison of the amount of water supply held in each of the major reservoirsIf the total earth’s water supply was a 55 gallon drum

The Origin of Sea Salts The Origin of Sea Salts • The sea became salty because of chemicals leached from The sea became salty because of chemicals leached from

the rocks of the crust, plus some volatile chemicals the rocks of the crust, plus some volatile chemicals ((hydrochloric acidhydrochloric acid and and hydrogen sulfidehydrogen sulfide) released ) released from the Earth's interior and by volcanoes. from the Earth's interior and by volcanoes.

• Probably, the ocean was salty as soon as it formed. More Probably, the ocean was salty as soon as it formed. More salts have accumulated gradually, as more of the rocks of salts have accumulated gradually, as more of the rocks of the crust were broken down by water (the crust were broken down by water (weatheredweathered).).

• The composition of the sea salt has been about the same The composition of the sea salt has been about the same for about 1 billion years. That is because a balance exists for about 1 billion years. That is because a balance exists between input of salts (mainly by between input of salts (mainly by riversrivers) and output ) and output (mainly by (mainly by sedimentssediments).).

• The The early oceanearly ocean, 3.8 billion years ago, was probably , 3.8 billion years ago, was probably similar in composition to today, except for changes similar in composition to today, except for changes caused by living things. The most important of these is caused by living things. The most important of these is the the production of oxygenproduction of oxygen by plants. by plants.

The The Origin Origin of Lifeof Life

Europa (Moon of Jupiter)- Icy Crust

Other Ocean WorldsOther Ocean Worlds

Drainage Systems on Mars

Ice

Sand