Geological Dating And Fossils

Front 1

Principle of Superstition

Back 1

Something is always younger than anything it is on top of and always older than anything that is on top of it.

Front 2

Law of Included Fragments

Back 2

Erosion of the oldest rock may mean there are fragments of that rock included in a younger, overlying rock. The included fragments belong to a rock older than the rock they are included in.

Front 3

Law of Uniformitarianism

Back 3

The present is the key to the past- How something used to live by looking at a fossil and living thing.

Front 4

Facies

Back 4

Lithofacies- rock

Biofacies- biology

Basic unit of geology which reflects the depositions environment.

Front 5

Freezing as preservation

Back 5

All parts of body preserved without alteration.

Front 6

Mummification

Back 6

“Drying out” -Dessication

Preserved in Amber where the resin kills the insect by dehydrating them- produces an antiseptic environment where bacteria can’t survive.

Front 7

Carbonisation

Back 7

The most stable molecules in a body (Carbon)

Other atoms react to form new minerals which are driven off whereas the carbon is left behind as a black film, frequently seen coating an impression of an organism.

Front 8

Petrification

Back 8

Buried quickly, water perculates underground, mineralisation of water, silica takes place of rotting body (mineral replacement)

Front 9

Less bones

Back 9

Fossilize better as there’s less weaknesses

Front 10

Ocean animals

Back 10

Preserve better- more sedimentation in ocean which will bury remains quicker.

Front 11

Moulds and casts

Back 11

Buried, decomposes, leaves mould, water perculates and replaces the space.

Front 12

Trace fossils

Back 12

Sedimentary structures produced by activity of organisms. E.g tracks, trails, burrows, borings

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Der

Back 13

Preserved in life form, variety of sizes and ages

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Death assemblage

Back 14

Fully grown adults

Front 15

Derived fossils

Back 15

Fossils that are weathered out of exposed rock and deposited in new sediment

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Trilobites

Back 16

Back (Definition)

Front 17

Trilobites

Back 17

Eyes= shallow water

Large surface area= lived in soft sediment

Burrows= Antennae

Exclusively marine, good zone fossil (can identify what period of time one is in as they evolve quickly and have very different traits in each period)

Front 18

Epifaunal

Back 18

Lives on seabed

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Infaunal

Back 19

Lives on sea bed

Front 20

Deposit feeders and filter feeders- Trilobites

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Deposit= eats detritus

Filter= strains through water to absorb nutrients from it

Front 21

Graptolites

Back 21

Also good zone fossils as they evolve quickly with distinctive groups in each new age. Always found in shales= deep marine environment.

Front 22

Graptolites

Back 22

Stipes decrease over time

Front 23

Brachiopods

Back 23

Still alive- can use uniformitarianism

Live in or on seabed in salt water

Eats by filter feeding

Can study past environments as they have certain characteristics e.g winged to stop being knocked over in High energy

Front 24

Brachiopods

Back 24

Back (Definition)

Front 25

Brachiopods

Back 25

Back (Definition)

Front 26

Role of the commisure

Back 26

The commisure is the line of closure of the two valves. This can be a variety of shapes depending on the environment.

E.g zig zag commissure allows larger areas of entry for nutrients but ensures larger clastic particles can’t enter

Front 27

Adductor and diductor muscles

Back 27

Adductor- close the valves

Diductor- open valvss

Front 28

Bivalves

Back 28

Filter feeders

Hinges vary due to environment e.g straight hinge=low energy environment

Front 29

Bivalves

Back 29

Back (Definition)

Front 30

Bivalves

Back 30

Back (Definition)

Front 31

Ammonites

Back 31

Back (Definition)

Front 32

Ammonites

Back 32

Goniatites= simple lobes and saddles (youngest)

Ceratites= simple saddles, complex lobes

Ammonites- free lobes and saddles

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Graptolites, Trilobites...cora

Back 33

Zone fossils for time and location as:

Wide and plentiful distribution

Ready preservation

Rapid evolutionary change

Easy identification of index fossils

High degree of facies independence (a rock or fossil with specific characteristics)

Front 34

Corals

Back 34

Environmental indicators:

Marine conditions

Warm water

Clear water to let sun through for photosynthesis

Shallow water

High energy so it’s aerated

Front 35

Corals

Back 35

Back (Definition)

Front 36

Plants

Back 36

Usually found in black shale- no oxygen, no bacteria, well preserved

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Plants

Back 37

Back (Definition)

Front 38

Plants

Back 38

Back (Definition)