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38 Cards in this Set

  • Front
  • Back

Principle of Superstition

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

Law of Included Fragments

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.

Law of Uniformitarianism

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


Lithofacies- rock

Biofacies- biology

Basic unit of geology which reflects the depositions environment.

Freezing as preservation

All parts of body preserved without alteration.


“Drying out” -Dessication

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


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.


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

Less bones

Fossilize better as there’s less weaknesses

Ocean animals

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

Moulds and casts

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

Trace fossils

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


Preserved in life form, variety of sizes and ages

Death assemblage

Fully grown adults

Derived fossils

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


Back (Definition)


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)


Lives on seabed


Lives on sea bed

Deposit feeders and filter feeders- Trilobites

Deposit= eats detritus

Filter= strains through water to absorb nutrients from it


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


Stipes decrease over time


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


Back (Definition)


Back (Definition)

Role of the commisure

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

Adductor and diductor muscles

Adductor- close the valves

Diductor- open valvss


Filter feeders

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


Back (Definition)


Back (Definition)


Back (Definition)


Goniatites= simple lobes and saddles (youngest)

Ceratites= simple saddles, complex lobes

Ammonites- free lobes and saddles

Graptolites, Trilobites...cora

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)


Environmental indicators:

Marine conditions

Warm water

Clear water to let sun through for photosynthesis

Shallow water

High energy so it’s aerated


Back (Definition)


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


Back (Definition)


Back (Definition)