MRS. STAHLMARINE BIOLOGY

Unit 4 & 5Geology of the Ocean,

Water, Waves, and Tides

Some FactsSolar system was formed more than 5

billion years ago, with Earth forming 400 million years later.

Surface was so hot that water could not remain there because there was no free oxygen gas in the atmosphere

Ocean began forming 4.2 billion years ago

Life first evolved in the oceanOcean covers 70.8%

How did the ocean form?

Hypothesis is: Earth was composed of cold matter and over time energy from space and radioactive decay causes the temperatures to rise.

Process continued for several hundred million years until the core of the Earth was hot enough to melt iron and nickel.

Elements melted -> moved to the core-> raising temps to 2,000 C

Molten material moved to the surface and spread out, continued to melt and solidify, creating our landscape separating the lighter elements from the denser ones.

They think that if there was any water present that it was stored up in the Earth’s minerals. Then continuous heating and cooling took place and water vapor was carried to the surface, it cooled, condensed, and formed the ocean!

Origin of LifeAtmosphere was originally made up of

gases like carbon monoxide, carbon dioxide, methane, nitrogen, and ammonia. Oxygen is chemically active so any other free oxygen gas present would have combined with some other element forming oxides. Therefore, oxygen did not start to accumulate in the atmosphere until the evolution of modern photosynthesis.

Oxides- Chemical compound containing at least one oxygen atom as well as another element.

Biologists also theorize that the molecules (carbon monoxide, carbon dioxide, nitrogen, methane, and ammonia) formed and accumulated in the ocean and over time the ocean turned into a huge, highly concentrated bowl of nutrient soup.

The molecules then became organized and the first cells evolved.

There wasn’t any oxygen so the first cells had to be anaerobic.

The first cells were also heterotrophs or relied on others for food.

The oldest marine fossil is marine bacteria (cyanobacteria) and was found in NW Australia between 3.4 and 3.5 billion years old.

The Ocean Today

The Ocean Today

139 million square miles, 362 X 10^18 gallons

362,000,000,000,000,000,000 gallons of water

Largest habitat on the planetReferred to as the world ocean

There are Four Major Basins

1.Pacific2.Atlantic3.Indian 4.Arctic

The area around Antarctica is referred to as the

Southern or Antarctic

Body of Water Define Examples

SeaBody of

saltwater that is smaller than an

ocean and landlocked.

Mediterranean Sea

Red SeaCaribbean Sea

GulfSmaller body of

water that is mostly cut off

from the larger ocean or sea by land formations.

Gulf of California

Gulf of Mexico

Persian Gulf

Continental Drift

The movement of the seafloor caused by the continuous movement o the continents that rest on it.

The seafloor is constantly being replaced with new seafloor, therefore organisms have to adapt constantly.

Lithosphere Asthenosphere

- Rock Sphere

- Tectonic plate

- Very strong

- Weak

- Easily deformed layer of

the Earth

- Acts as a “lubricant” for

the plates to slide

Oceanic Crust Continental Crust

- Basalt

- Thin crusts under the

oceans

- Thinner and denser

- More active

- Granite

- Floats on top of Mantle

- Makes up the

continents

19th CenturyEdward Suess

Early 1600’sSir Frances Bacon

1915Alfred Wegener

1960’sH.H. Hess

Continents may have once been connected to each other. Continents may have once been connected to each other.

Proposed Gondwanaland- fusion of Southern Continents (S. America, Africa, India, Antarctica, and Australia).

Proposed Gondwanaland- fusion of Southern Continents (S. America, Africa, India, Antarctica, and Australia).

One supercontinent= Pangaea. Forces of the Earth’s rotation separated the continents.

One supercontinent= Pangaea. Forces of the Earth’s rotation separated the continents.

Molten rock / Magma in the mantle moved by convection currents (heating and cooling of magma).

Molten rock / Magma in the mantle moved by convection currents (heating and cooling of magma).

Moving ContinentsTimeline of Moving Continents

Pangaea

The man of Pangaea is

Alfred Wegener

Evidence of Continental Drift

1. Continental plates fit together like a puzzle.

2. Distribution of Earthquakes -> occur in narrow zones that correspond to areas along ridges and trenches. Most active areas of crustal movement.

3. Temperature of Sea Bottom-> highest temps at ridges. Temps decrease with distance from ridges. Why do you think that is?????

Heating magma oozing out.

4. Age of rock samples from seafloor. Youngest rock was found near ridges and older rocks were found further away.

5. Fossils collected on opposite coasts were similar.

6. Coal deposits and other geological formations matched up on opposite sides of the Atlantic.

7. Sediment gets thicker and thicker as you move away from the ridges.

8. Seafloor Spreading-> basalt magma from the mantle rises to create new ocean floor at mid-ocean ridges. On each side of the ridge, sea floor moves from the ridge towards the deep sea trenches, where it is subducted or sucked back into and recycled back into the mantle

9. Magnetic evidence-> * 170 reversals in the past 76 million

years (north / south polarity switched back and forth). Reverses directions.

* Caused by fluctuations in the movement of material in iron-nickel outer core.

* When rocks are in the molten stage they are free to move around and act like tiny little compasses pointing either north or south.

* When the rocks cool they keep whatever their orientation is. There are literally stripes on the rocks that show the magnetic bands and they match up on either side of the mid ocean ridge= magnetic anomalies.

Continental Drift was not accepted at first because:

Scientists thought that he did not have enough evidence to prove his theory.

Laurasia consisted of: Europe, Asia, and North America

Gondwanaland- S. America, Africa, India, Antarctica, and Australia

The Forces that Drive Continental Movement

HH HessConvection currents- the way magma moves. Magma

rises from the Earth’s core to the upper mantle because its less dense than the surrounding material. When it reaches the mantle it cools, becomes more dense, and sinks back into the core. This recycling causes changes in temperature called convection.

Volcanoes form when the magma breaks through the Earth’s crust.

Lines of volcanoes form underwater mountain ranges = midocean ridges

When it cools, it forms new crust = oceanic basaltic crust

Rift ValleyWhere the Earth’s crust is splitting apartNarrow, steep sides, flat floorLooks like a ditchCreated by tectonic activityHigh volcanic activity.

Tanzania’s Great

Rift Valley

Fracture Zones-

Linear regions of unusually irregular sea bottom.

Almost like cracks in the crust

SUBDUCTION ZONES

Regions where the old material / sinks down into the mantle and when it hits the magma of the mantle it liquefies and recycles itself through convection currents into the core.

Seafloor Spreading

Oceanic plates are diverging from one another, the magma rises along a rift zone and spreads out at the surface building new sea floor. The age of the rocks increases as one moves away from the rift zone. The mid-oceanic ridge is the primary site for sea-floor spreading. Earthquakes and volcanoes are where seafloor spreading is occurring.

Theory of Plate Tectonics

The lithosphere is viewed as a series of rigid plates that are separated by earthquake belts that are located around trenches, ridges, and faults.

Seven Major Plates are:

1._Pacific2. North American3. Eurasian4. South American5. African6. Antarctic7. Australian

Where plate boundaries move apart and new lithosphere is

formed divergent plate boundaries occur. Where the old lithosphere is destroyed

because the plates move toward each is called

convergent plate boundaries.Where the plates move past

each other = Faults.

Transform Fault

Special kind of fault that is found in sections of the mid-ocean ridge. Each side is formed by a different plate and the plates scrape against each other

Rift Zones

Where the lithosphere splits, separates, and moves apart as new crust is formed.

Rift Communities / Deep Sea Vents

Thriving communities of marine organisms

Depend on chemosynthetic activity of bacteria for their nutrients.

Represent food webs that exist in the absence of sunlight.

The Ocean Bottom

Bathygraphic Features

Physical features of the ocean bottom

The ocean bottom is divided into two different regions the Continental Margin and the Ocean Basin.

Continental MarginsRegion that lies beneath the neritic zone.

Consists of continental shelf and continental slope

Composed of granite that is covered by sediment and have similar features to the edge of the nearby continent.

See Figure 3-12 on page 56 to discuss the formation of the continental shelf.

Continental Shelf

Generally flat areas 40 miles wide and 430 feet deepSlopes gently toward the bottom of the ocean basin

Produced by waves that constantly erode land mass and by natural dams, reefs, rocks, and volcanic barriers.

Continental SlopeTransitional levelShelf break is where the shelf ends and the

slope beginsShelf break is where there is a rapid change

in depth to the seafloor Less sedimentSubmarine Canyons-> aligned with river

systems on land and they create a ripple effect on the sea floor. At the end it fans out = Deep Sea Fan.

They are formed by turbidity currents = underwater avalanches of sediment (large accumulations of sediment collapse).

Continental Rise

small slope at the base of the continental slope. Created by landslides that carry sediment to the bottom of the slope.

The Ocean Basin:

SeafloorFour Main basins: Pacific, Atlantic, Indian, and Arctic

Composed of Basalt Rock covered with a thick blanket of sediment.

Abyssal Plains and Hills

Bottom of the ocean basinFlatFormed by sediment from turbidity currents

Spread out on the ocean floor are abyssal hills (3300 ft. high).

Formed by volcanic activity

Seamounts

Steep sided formation that rises sharply from the bottom.

Formed by underwater volcanoes

Some show us coral reef activity and erosion proving that they may have been above water at one point in time.

Ridges and Rises

Series of large, underwater volcanic mountains that run through every ocean.

Separates the ocean basins

Trenches

Most common in the Pacific Ocean

Mariana Trench-> the deepest spot on the Earth is the Challenger Deep and is 6.85 miles deep.

The Ocean Floor

Continental shelf is very productive because it relatively shallow and provides lots of sunlight and nutrients.

Abundant marine life on the shelfNo sunlight in the abyss.Limited to chemosynthetic bacteria in

vent communitiesOcean floor organisms rely heavily on

organisms falling from above.

Composition of the Seafloor

The entire seafloor is made up of basalt rock with a blanket of sediment on top.

Sediment is made up of: Living organisms land Atmosphere Sea that accumulates over time

Why is the sediment so important to organisms that live on the

continental slope, shelf, and abyssal plains?

Provides a habitat for many organisms and a source of nutrients for others.

Five types of sediment:BiogenousHydrogenousTerrigenousCosmogenousLithogenous

HydrogenousForms when dissolved materials come

out of a solution such as a precipitate.Precipitation is caused by changes in

temperature, pressure, and chemically active fluids.

Types include: Manganese nodules (ore material in the ocean that comes

from terrigenous, volcanic, and also hydrothermal material)

Phosphates Evaporative salts Metal sulfides Carbonates (rocks with high amounts of calcium).

LithogenousComposed of fragments of Pre-existing

rock materialFormed by Physical and Chemical

Weathering-> break-up of exposed rock, movement of sediment, and large particles of rock that are deposited near the edges of the continents and it accumulates

Most is made up of quartzWhere is it found? -> Neritic zone (near

shore), beaches, continental shelves, pelagic zones (deep sea floor).

BiogenousSkeletons and shells of dead marine

organisms.Biogenous ooze= made up of 30% of

microscopic shells. When it hardens it turns into rock and can make chalk or Diatomaceous Earth.

Calcareous ooze= Calcium carbonate= Coccolithophorians (algae) and Foraminiferans (protozoan’s)

Silicareous ooze= Silica= Radiolarians (Protozoan’s) and Diatoms (algae)

Found in the Pelagic zone

Foraminiferans

Coccolithophorians

Radiolarians

Diatoms

Terrigenous

Found in the deep sea and is formed by accumulation of turbidites

Turbidites are sea-bottom deposits formed by massive slope failures where rivers have deposited large deltas. These slopes fail in response to earthquake shaking or excessive sedimentation

Turbidites

Cosmogenous

Composed of material from outer space

Space dust and meteor debris

Forms an insignificant amount of ocean sediment