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THE FOSSIL RECORD Movement of Ocean Water Surface currents Coriolis Effect. THE FOSSIL RECORD Movement of Ocean Water Surface currents Currents are also affected by the Earth's rotation through the Coriolis Effect . Currents in the northern hemisphere tend to be

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Presentation Transcript
slide1

THE FOSSIL RECORD

Movement of Ocean Water

Surface currents

Coriolis Effect

slide2

THE FOSSIL RECORD

Movement of Ocean Water

Surface currents

Currents are also affected by the Earth's rotation

through the Coriolis Effect.

Currents in the northern hemisphere tend to be

deflected toward the right (or clockwise), and

currents in the southern hemisphere tend to be

deflected to the left (or counter clockwise) as a result

of the Coriolis Effect.

slide3

THE FOSSIL RECORD

  • Movement of Ocean Water
  • Thermohaline currents
      • Thermohaline currents are initiated at the ocean
      • surface by temperature and salinity conditions.
      • Gravity acts to pull colder (or more saline) denser
      • water downward, displacing less dense water
      • upward.
slide4

THE FOSSIL RECORD

Movement of Ocean Water

Thermohaline currents

slide5

THE FOSSIL RECORD

Movement of Ocean Water

Tides

  • Tidesare generated by the effect of the Moon's
  • gravity (and to a lesser extent, the Sun's gravity)
  • on the oceans.
slide6

THE FOSSIL RECORD

Movement of Ocean Water

Tides

  • Areas that are alternately submerged and exposed
  • by rising and falling tides are called tidal flats.
slide7

THE FOSSIL RECORD

Water Temperature and Depth

Water temperature varies with latitude

slide8

THE FOSSIL RECORD

Water Temperature and Depth

Water temperature also varies with depth

slide9

THE FOSSIL RECORD

Water Temperature and Depth

A zone of rapid temperature decrease with depth in a

water mass is called the thermocline.At great ocean depths, temperatures may be just

above freezing.

slide10

THE FOSSIL RECORD

Light

The well-illuminated water near the surface of the

ocean is called the photic zone.

slide11

THE FOSSIL RECORD

Light

Light is used by certain organisms in the water for

photosynthesis.

Photosynthetic organisms are restricted to the

near-surface waters.

slide12

THE FOSSIL RECORD

Light

  • Light penetration into the sea depends on:
    • Sun angle
slide13

THE FOSSIL RECORD

Light

  • Light penetration into the sea depends on:
    • Atmospheric conditions
slide14

THE FOSSIL RECORD

Light

  • Light penetration into the sea depends on:
    • Conditions at the water surface
slide15

THE FOSSIL RECORD

Light

  • Light penetration into the sea depends on:
    • Clarity of the water (or conversely, the amount of
    • suspended sediment in the water)
slide16

THE FOSSIL RECORD

Light

In some areas, light may penetrate as deep as 200 m or more,

but generally there is light adequate to support

photosynthesis only in the upper tens of meters of the sea

(to perhaps 100 m).

slide17

THE FOSSIL RECORD

Seafloor Sediments

Terrigenous Sediments

Material weathered from the continents

Mostly silt and clay

slide18

THE FOSSIL RECORD

Seafloor Sediments

Biogenic or Organic Sediments

Sediment of biologic origin

slide19

THE FOSSIL RECORD

Seafloor Sediments

Biogenic or Organic Sediments

Calcareous oozes

Form in depths <4000 m

Foraminifera, coccolithophores,

and pteropods

slide20

THE FOSSIL RECORD

Ocean Chemistry

Carbonate Compensation Depth

The Carbonate Compensation

Depth or CCD is a

particular depth in the

oceans (varying from

place to place), which

effects where calcareous

oozes may or may not

accumulate.

slide21

THE FOSSIL RECORD

Ocean Chemistry

Carbonate Compensation Depth

Above the CCD, water is warmer,

and precipitation of CaCO3 is

greater than dissolution.

Calcareous plankton can be found

in the water column, and on

the bottom.

Bottom sediments can consist of

calcareous sediments forming

chalk or limestone.

slide22

THE FOSSIL RECORD

Ocean Chemistry

Carbonate Compensation Depth

  • Below the CCD, water is colder, and
  • CaCO3 tends to dissolve
  • (dissolution is greater than
  • precipitation)
  • Tiny shells of CaCO3 dissolve, and
  • do not accumulate on the bottom
  • if water is deeper than the CCD
    • Below the CCD, the bottom
    • sediments consist of clay and
    • siliceous ooze
slide23

THE FOSSIL RECORD

Seafloor Sediments

Biogenic or Organic Sediments

Calcareous oozes

slide24

THE FOSSIL RECORD

Seafloor Sediments

Biogenic or Organic Sediments

Siliceous oozes

Form in cold, deep water

Radiolarians and diatoms

slide25

THE FOSSIL RECORD

Seafloor Sediments

Biogenic or Organic Sediments

Phosphatic sediments

Fish bones and teeth

slide26

THE FOSSIL RECORD

Seafloor Sediments

Hydrogenous Sediments

Manganese nodules

(Authigenic or

diagenetic minerals)

Minerals that precipitate

from sea water by chemical

reactions.

slide27

THE FOSSIL RECORD

Reconstructing Ancient Geography

slide28

THE FOSSIL RECORD

Ancient Climatic Conditions

Fossils can be used to interpret paleoclimates or ancient climates

Fossil spore and pollen grains

slide29

THE FOSSIL RECORD

Ancient Climatic Conditions

Presence of corals indicates tropical climates

slide30

THE FOSSIL RECORD

Ancient Climatic Conditions

Plant fossils showing

aerial roots,

drip tips on leaves

lack of yearly rings,

large wood cell structure

Indicate tropical climates

slide31

THE FOSSIL RECORD

Ancient Climatic Conditions

Marine molluscs (clams, snails, etc.) with spines and thick shells

inhabit warm seas

slide32

THE FOSSIL RECORD

Ancient Climatic Conditions

Planktonic organisms vary in size and coiling direction

according to temperature

foraminifer Globorotalia

Right coiled

warm

Left coiled

cold

slide33

THE FOSSIL RECORD

Ancient Climatic Conditions

Oxygen isotope ratios in shells.

16O evaporates easier than oxygen-18 because it is lighter.

16O falls as precipitation and gets locked up in glaciers,

leaving sea water enriched in 18O during glaciations.

Shells that are enriched in 18O indicate times of glaciation.

slide34

THE FOSSIL RECORD

Ancient Climatic Conditions

slide35

THE FOSSIL RECORD

Extinctions

The history of life has been marked by extinctions.

The five largest extinction events are termed mass extinctions.

These mass extinctions were sudden, global in extent, and very

devastating.

Mass extinctions occurred at the ends of the following periods:

Ordovician

Devonian (roughly 70% of the ocean's invertebrates disappeared)

Permian (the greatest extinction. More than 90% of all marine

species at that time disappeared or nearly went extinct)

Triassic

Cretaceous (affecting the dinosaurs ano other animals on land

as well as organisms in the sea, about one fourth of all

known families of animals became extinct)